Cisco CCNA Help Document

Cisco konfiguracija

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Remember, however, that Packet Tracer is not a substitute for a hands-on lab experience with real

equipment.

Termini i kodovi

Na PC:

SET IP=xxx.xxx.xxx.xxx

SET GATEWAY=xxx.xxx.xxx.xxx

SET SUBNETMASK=xxx.xxx.xxx.xxx

SET DNS=xxx.xxx.xxx.xxx

ECHO testing network with ping

ipconfig /all

ping xxx.xxx.xxx.xxx

Briefly hold down the keys <CTRL><SHIFT>6, release and press x

From the user exec mode, enter privileged exec mode:

Router> enable

From the privileged exec mode, enter global configuration mode:

Router# configuration terminal ili configure

----------------------------------------------------------

Podesavanje:

RUTER i podesavanja/konfiguracije/podesavanja rutera

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1.

Step 1: Podesavanje Imena Ruteru

Set the device hostname to Router1:

router(config)# hostname Router1

2. Configure a message-of-the-day banner

POdesavanje Banera na Ruteru

Configure the MOTD banner. The MOTD banner is displayed on all connections before the login

prompt.

banner motd % Ovde se kuca opis rutera %

ili može:

R1(config)#banner motd

#

Enter TEXT message. End with the character '#'.

This is Router1

#

**********

3. Configure an EXEC mode password.

POdesavanje Administratorske sifre

Set the privileged exec password to cisco.

Router1(config)# enable secret cisco - Setup the secret password (or enable password)

Ili njeno brisanje:

R1(config)#no enable password

R1(config)#

************

4. Disable DNS lookup

Step 5: Disable DNS lookup with the no ip domain-lookup command.

R1(config)#no ip domain-lookup

R1(config)#

*************

5. Configure a password for console connections.

POdesavanje Sifre na Konzoli

Step 2: Configure the console password.

Set the console access password to class. The console password controls console access to the

router.

Router1(config)# line console 0 -Setup console

Router1(config-line)# password class

Router1(config-line)# login

********

6.Configure a password for VTY connections.

Podesavanje Sifre na Telnetu

Step 3: Configure the virtual line password.

Set the virtual line access password to class. The virtual line password controls Telnet access to the

router.

Router1(config-line)# line vty 0 4 - telnet passwords

Router1(config-line)# password class

Router1(config-line)# login

*************

7.

Step 4:

Podesavanje interfejsa FastEnthernet 0/0:

Router1(config)# interface fa0/0

Router1(config-if)# description Connection to Host1 with crossover cable

Router1(config-if)# ip address address mask

Router1(config-if)# no shutdown

Router1(config-if)# end

Router1#

8.

Step 5:

Display the contents of NVRAM. If the output of NVRAM is missing, it is because there is no saved

configuration.:

Router1# show startup-config

startup-config is not present

Router1#

9.

Display the contents of RAM.

Router1#show running-config

10.

Save RAM configuration to NVRAM.

For a configuration to be used the next time the router is powered on or reloaded, it must be

manually saved in NVRAM.

Save the RAM configuration to NVRAM:

Router1# copy running-config startup-config --- ili samo wr --- ili copy run start - snimanje (save)

configuracije

Destination filename [startup-config]? <ENTER>

Building configuration...

[OK]

Podesavanje IP adrese kod rutera

Router(config)#interface FastEthernet 0/0

Router(config)#description Connects to main switch in Building A

Router(config-if)#ip address 192.168.10.1 255.255.248

Router(config-if)#no shutdown //aktiviranje interfejsa, samo shutdown deaktiviranje

Router(config-if)# exit

Router(config)#

Router(config)#interface Serial 0/0/0

Router(config-if)#192.168.10.1 255.255.248

Router(config-if)#clock rate 56000

Router(config-if)#no shutdown

11.

Router show Commands:

Step 1 Enter the show running-config command to display the contents of the currently running

configuration file.

Step 2 Enter the show startup-config command to display the startup configuration.

Step 3 Enter the show interfaces command to display the statistics for all interfaces.

Step 4 Enter the show version command to display the information about the currently loaded

software version along with hardware and device information.

Step 5 Enter the show ip interface brief command to display a summary of the usability status

information for each interface.

Rezime, osnovne show posle konfigurisanje su:

show running-config

show ip route

show ip interface brief

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Neka još možda i ista podesavanja:

*********************************************

Router>enable

Router#

Configure the router hostname:

II) apply a unique hostname to the router

Router(config)#hostname R1

R1(config)#

III) Configure an EXEC mode password: (sifra/pasword za ulazak u privilegovan mod)

configure a password that is to be used to enter privileged EXEC mode. In our lab environment, we

will use the password class

Router(config)#enable secret class

IV)

a) configure the console and

b) Telnet lines with the password cisco.

Once again, the password cisco is used only in our lab environment.

Rešavanje:

- c) Configure an EXEC timeout of 15 minutes

The exec-timeout will terminate an exec session after the session has been idle for the configured

exec-timeout time. The default is 10 minutes.

An absolute timeout however is a the maximum amount of time a single session can remain

established. So if you have an absolute timeout of 12 minutes than even if the user is active, the

session will be disconnected at after 12 minutes.

d) Synchronize unsolicited messages and

Sintaksa:

Pali: logging synchronous [level {severity-level | all}] [limit number-of-buffers]

Gasi: no logging synchronous

- level severity-level | all - (Optional) Specifies the message severity level. Messages with a severity

level equal to or higher than this value are printed asynchronously. Low numbers indicate greater

severity and high numbers indicate lesser severity. The all option specifies all messages are printed

asynchronously, regardless of the severity level. The default value is 2.

- limit number-of-buffers - (Optional) Specifies the number of buffers to be queued for the

terminal after which new messages are dropped. The default value is 20.

This feature is turned off by default.

If you do not specify a severity level, the default value of 2 is assumed.

If you do not specify the maximum number of buffers to be queued, the default value of 20 is

assumed.

e) debug output with solicited output and prompts for the console and virtual terminal lines.

R1(config)#line console 0

R1(config-line)#password cisco

može i:

R1(config-line)#logging synchronous ili

Router(config-line)# logging synchronous level 7 limit 70000 - ovo je sa svim uslkucenim

mogucim opcijama

R1(config-line)#exec-timeout 15

R1(config-line)#login

R1(config-line)#exit

R1(config)#line vty 0 4 a može i odmah bez exit: R1(config-line)#line vty 0 4

R1(config-line)#password cisco

a može se doda i:

R1(config-line)#logging synchronous

R1(config-line)#exec-timeout 0 0 - prva 0 su minuti, druga 0 sekunde, po defaultu je 10 min

R1(config-line)#login

R1(config-line)#exit

A mogu da stavim i apsolutan:

#line vty 0 4

R1(config-line)#no exec-timeout

R1(config-line)#absolute-timeout 2

R1(config-line)#end

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- exec-timeout command - malope uključena inače je opciona

********************************

To set the interval that the EXEC command interpreter waits until user input is detected, we can use

the exec-timeout line configuration command. If no input is detected during the interval, the EXEC

facility resumes the current connection. If no connections exist, the EXEC facility returns the terminal

to the idle state and disconnects the incoming session

Sintaksa je sledeća:

Router(config-line)#exec-timeout minutes [seconds]

Syntax description:

minutes—Integer that specifies the number of minutes.

seconds—(Optional) Additional time intervals in seconds.

In a lab environment, you can specify ―no timeout‖ by entering the exec-timeout 0 0 command. This

command is very helpful because the default timeout for lines is 10 minutes. However, for security

purposes, you would not normally set lines to ―no timeout‖ in a production environment.

V) Configuring a Banner. From the global configuration mode, configure the message-of-the-day

(motd) banner.

R1(config)#banner motd #

***

- enable secret

Enter the command enable secret >class< to set an encrypted password used to enter privileged

EXEC mode.

- line con 0

Enter the command line con 0 to enter line configuration mode for the console line. Notice the

change in the prompt.

- password

Enter the command password cisco to set the console password. Enter the command login to require

use of the password when logging in via the console port. Enter the command exit to return to global

configuration mode.

-line vty 0 4

Enter the command line vty 0 4 to enter line configuration mode for all five virtual terminal lines.

Enter the command password cisco to set the vty password. Enter the command login to require use

of the password when telnetting to the router.

***

It is good practice to configure a description on each interface to help document the network

information. The description text is limited to 240 characters

R1(config-if)#description Veza sa R2

***

When cabling a point-to-point serial link in our lab environment, one end of the cable is marked DTE

and the other end is marked DCE. The router that has the DCE end of the cable connected to its serial

interface will need the additional clock rate command configured on that serial interface.

R1(config-if)#clock rate 64000

-------------------------------

Dodatne funkcije:

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-- no ip domain-lookup - da kad u default modu rada ukucamo nešto progrešno ne pokušava da se

telnetuje na server tj da ga traži već da javi kao gršku, tada će mislim tražiti reč telnet - disable DNS

na ruteru tj iskljucivanje DNS-a

-- Router(config-line)#logging synchronous - In other words, the logging synchronous

command prevents IOS messages delivered to the console or Telnet lines from interrupting your

keyboard input. Primer gde se korsiti:



R1(config-line)#line vty 0 4


--To set the interval that the EXEC command interpreter waits until user input is detected, we can use

the exec-timeout line configuration command:

!!!< Router(config-line)#exec-timeout minutes [seconds] >!!!

Syntax description:

minutes—Integer that specifies the number of minutes.

seconds—(Optional) Additional time intervals in seconds.

a ako hoćemo no timeout onda pišemo: exec-timeout 0 0

Primer:


R1(config-line)#exec-timeout 0 0

R1(config-line)#line vty 0 4

R1(config-line)#exec-timeout 0 0

--R1#debug ip routing --

IP routing debugging is on

The debug ip routing command shows when routes are added, modified, and deleted from the

routing table

a da se isključi:

R1(config-if)#end

R1#no debug ip routing

IP routing debugging is off

__________________________

-- Dodavanje STATIČKE rute -- Statičko rutiranje

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Static routing has several primary uses, including:

Providing ease of routing table maintenance in smaller networks that are not expected to grow

significantly.

Routing to and from stub networks (see Chapter 2).

Use of a single default route, used to represent a path to any network that does not have a more

specific match with another route in the routing table.

Static routing advantages:

Minimal CPU processing.

Easier for administrator to understand.

Easy to configure.

Static routing disadvantages:

Configuration and maintenance is time-consuming.

Configuration is error-prone, especially in large networks.

Administrator intervention is required to maintain changing route information.

Does not scale well with growing networks; maintenance becomes cumbersome.

Requires complete knowledge of the whole network for proper implementation.

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Način 1:

***********

!!!< Router(config)# ip route network-address subnet-mask ip-address >!!!

gde je:

network-address:—Destination network address of the remote network to be added to the

routing table.

subnet-mask—Subnet mask of the remote network to be added to the routing table. The subnet

mask can be modified to summarize a group of networks.

ip-address—Commonly referred to as the next-hop router’s IP address

Primer:

R3(config)#ip route 172.16.1.0 255.255.255.0 192.168.1.2

U ruting tabeli se vidi da je statičke jer ima S ispred:

S 172.16.1.0 [1/0] via 192.168.1.2 - staicka

C 192.168.1.0/24 is directly connected, Serial0/0/1 - podesen serial

C 192.168.2.0/24 is directly connected, FastEthernet0/0 - podeseni Ethernet

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Način 2:

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-- STATIČKA ruta preko određenog interfejsa umesto specificiranje NextHopa --

To configure static routes with an exit interface specified, use the following syntax:

!!!< Router(config)# ip route network-address subnet-mask exit-interface >!!!

network-address—Destination network address of the remote network to be added to the

routing table.

subnet-mask—Subnet mask of the remote network to be added to the routing table. The subnet


exit-interface—Outgoing interface that would be used in forwarding packets to the

destination network.

Primer:

R3 router as the exit interface.

R3(config)# ip route 172.16.2.0 255.255.255.0 Serial0/0/1

--- kofiguracija DEFAULT rute ---

Configure the R1 router with a default route using the interface option on Serial 0/0/0 of R1 as the

nexthop interface.

!!!< R1(config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2 >!!!

gde će sad:

R1 router now has a default route, the gateway of last resort, and will send all unknown

traffic out Serial 0/0/0, which is connected to R2.

-- brisanje STATIČKIH ruta --

R3(config)#no ip route 172.16.1.0 255.255.255.0 192.168.1.2

R3(config)#no ip route 172.16.2.0 255.255.255.0 Serial0/0/1

-- service password-encryption - Encrypt the un-encrypted passwords with ‘service password-

encryption’ command and don’t forget to turn it off after you ‘show run’.

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Stub network & Static Routes (dodavanje Staticke IP adrese) - statičko rutiranje

**********************************************************************************

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Static routes are commonly used when routing from a network to a stub network.

--- A stub network is a network accessed by a single route. ---

Komande za dodavanje Statičke rute:

Router(config)#ip route prefix mask {ip-address | interface-type interface-number [ip-address]}

[distance] [name] [permanent] [tag tag]

1. network-address - Destination network address of the remote network to be added to the routing

table

2. subnet-mask - Subnet mask of the remote network to be added to the routing table. The subnet


3. ip-address - Commonly referred to as the next-hop router's IP address

4. exit-interface - Outgoing interface that would be used in forwarding packets to the destination

network

Primeri:

Router(config)#ip route 1.1.1.0 255.255.255.0 192.168.14.1 - rutiranje preko next-hope ip adresse

Router(config)#ip route 1.1.1.0 255.255.255.0 serial0/0 - rutiranje preko izlaznog interfejsa

Primer sa nula interfejsom: R2(config)#ip route 192.168.0.0 255.255.0.0 Null0

Router(config)#ip route 1.1.1.0 255.255.255.0 serial0/0 192.168.14.1 - rutiranje preko izlaznog

interfejsa i next-hope ip adrese

Router(config)#ip route 1.1.1.0 255.255.255.0 192.168.14.1 permanent - permanent označava da

ruta neće biti obrisana čak i ako iterfejs padne

Router(config)#ip route 1.1.1.0 255.255.255.0 192.168.14.1 91 - promena default administation

distance za statičku rutu (po defaultu je 1) na 91. Ova se zove (floating) lebdeća statična ruta.

Obično su default rute statičke i one se mogu dodavati:

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.14.1 - svi paketi koji su adresirani za mrežu koja se ne

nelazai u ruting tabeli ići će na nex-hope interfejs sa ip adressom 192.168.14.1

Router(config)#ip route 1.1.1.0 255.255.255.0 serial0/0 - sends all packets destined for networks not

int the routing table out from serial 0/0 interfaces.

--- Kada se korsite default statičke rute ---

Default static routes are used:

When no other routes in the routing table match the packet's destination IP address. In other words,

when a more specific match does not exist. A common use is when connecting a company's edge

router to the ISP network.

When a router has only one other router to which it is connected. This condition is known as a stub

router.

U ruting tabeli se pojavi kao:

S* 0.0.0.0/0 is directly connected, Serial0/0/0

Note the * or asterisk next to the S. As you can see from the Codes table in the figure, the asterisk

indicates that this static route is a candidate default route. That is why it is called a "default static"

route.

**********

Statičko rutiranje preko izlaznog interfejsa u odnosu na način preko next-hope ip-addrese

************

- The difference between an Ethernet network and a point-to-point serial network is that a point-to-

point network has only one other device on that network - the router at the other end of the link.

With Ethernet networks, there may be many different devices sharing the same multi-access

network, including hosts and even multiple routers. By only designating the Ethernet exit interface in

the static route, the router will not have sufficient information to determine which device is the next-

hop device

- POšto se može desi na nema dovoljno informacija i informacije koje su pouzdane:

R1 knows that the packet needs to be encapsulated in an Ethernet frame and sent out the

FastEthernet 0/1 interface. However, R1 does not know the next-hop IP address and therefore it

cannot determine the destination MAC address for the Ethernet frame.

- Možese desiti da statička ruta iz nekih razloga NE RADI, pa je preporučljivo:

This can be done by configuring the static route to include both the exit interface and the next-hop IP

address.

R1(config)#ip route 192.168.2.0 255.255.255.0 fastethernet 0/1 172.16.2.2

The routing table entry for this route would be:

S 192.168.2.0/24 [1/0] via 172.16.2.2 FastEthernet0/1

****************************************************************

TroubleShooting - otklanjanje i nalaženje grešaka oko nestalih statičkih ruta, greške statičkog

rutiranja

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Troubleshooting a Missing Route

Networks are subject to many different forces that can cause their status to change quite often:

1. An interface fails.

2. A service provider drops a connection.

3. There is an over-saturation of links.

4. An administrator enters a wrong configuration.

What steps can you take?

ping

traceroute

show ip route

i može i:

show ip interface brief - gives you a quick summary of interface status.

- show cdp neighbors detail - CDP can help you gather information about the IP configuration of a

directly connected Cisco device using the show cdp neighbors detail command.

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------- Dinamičko Rutiranje - ruting protokoli, protokoli za rutiranje -------

**********************************************************************************

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Dinamički Ruting Protokoli:

Prednosti i Mane dinamickog rutiranja:

Dynamic routing advantages:

Administrator has less work maintaining the configuration when adding or deleting networks.

Protocols automatically react to the topology changes.

Configuration is less error-prone.

More scalable, growing the network usually does not present a problem.

Dynamic routing disadvantages:

Router resources are used (CPU cycles, memory and link bandwidth).

More administrator knowledge is required for configuration, verification, and troubleshooting.

Postoje 2 vrste Ruting protokola na osnovu Sabnet Maske (subnet musk) a to su:

1) Classful Routing Protocols

Classful routing protocols do not send subnet mask information in routing updates. The first routing

protocols such as RIP, were classful. This was at a time when network addresses were allocated

based on classes, class A, B, or C. A routing protocol did not need to include the subnet mask in the

routing update because the network mask could be determined based on the first octet of the

network address.

Classful routing protocols do not support variable length subnet masks (VLSM).

Their inability to support discontiguous networks.

2) Classless Routing Protocols

Classless routing protocols include the subnet mask with the network address in routing updates.

Today's networks are no longer allocated based on classes and the subnet mask cannot be

determined by the value of the first octet. Classless routing protocols are required in most networks

today because of their support for VLSM, discontiguous networks and other features

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POstoje 2 kategorije, odnsno 2 načina rada Interior Gateway Protocols (IGP) - protokole koji rade u

jednom ruting domenu:

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1)

----------- Distance Vector Routing Protocol Operation ----------------------

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Distance vector means that routes are advertised as vectors of distance and direction. Distance is

defined in terms of a metric such as hop count and direction is simply the next-hop router or exit

interface. Distance vector protocols typically use the Bellman-Ford algorithm for the best path route

determination.

Some distance vector protocols periodically send complete routing tables to all connected neighbors.

In large networks, these routing updates can become enormous, causing significant traffic on the

links.

Distance Vektor Ruting protokoli se koriste kada:

Distance vector protocols work best in situations where:

The network is simple and flat and does not require a special hierarchical design.

The administrators do not have enough knowledge to configure and troubleshoot link-state

protocols.

Specific types of networks, such as hub-and-spoke networks, are being implemented.

Worst-case convergence times in a network are not a concern.

Distance vector routing protocols include RIP, IGRP, and EIGRP

Ruteri koji zastupljaju ovaj način znaju samo:

The direction or interface in which packets should be forwarded and

The distance or how far it is to the destination network.

Routers using distance vector routing are not aware of the network topology.

Some distance vector routing protocols like EIGRP do not send periodic routing table updates.

*******************************************

Routing Loop - Petlje u Rutiranju

--------------------------------------------

Petlje u rutiranju mogu izazvati dosta manjih ili većih problema na mreži.

One mogu biti produkt - The loop may be a result of:

Incorrectly configured static routes

Incorrectly configured route redistribution (redistribution is a process of handing the routing

information from one routing protocol to another routing protocol and is discussed in CCNP-level

courses)

Inconsistent routing tables not being updated due to slow convergence in a changing network

Incorrectly configured or installed discard routes

The IP protocol has its own mechanism to prevent the possibility of a packet traversing the network

endlessly. IP has a Time-to-Live (TTL) field and its value is decremented by 1 at each router. If the TTL

is zero, the router drops the packet.

Mehanizmi i načini pomoću kojih se mogu rešiti i rešavaju se petlje u rutiranju:

1. Defining a maximum metric to prevent count to infinity

To eventually stop the incrementing of the metric, "infinity" is defined by setting a maximum

metric value. For example, RIP defines infinity as 16 hops - an "unreachable" metric. Once the routers

"count to infinity," they mark the route as unreachable.

2. Holddown timers

Holddown timers are used to prevent regular update messages from inappropriately reinstating a

route that may have gone bad. Holddown timers instruct routers to hold any changes that might

affect routes for a specified period of time.

3. Split horizon

The split horizon rule says that a router should not advertise a network through the interface from

which the update came.

4. Route poisoning or poison reverse

Route poisoning:

- is used to mark the route as unreachable in a routing update that is sent to other routers.

Unreachable is interpreted as a metric that is set to the maximum. For RIP, a poisoned route has a

metric of 16.

Poison reverse:

- The rule for split horizon with poison reverse states when sending updates out a specific interface,

designate any networks that were learned on that interface as unreachable.

5. Triggered updates

Distance vector routing protocols are like using road signs to guide you on your way to a destination,

only giving you information about distance and direction.

Distance vector routing protocols are like road signs because routers must make preferred path

decisions based on a distance or metric to a network. Just as travelers trust a road sign to accurately

state the distance to the next town, a distance vector router trusts that another router is advertising

the true distance to the destination network.

**********************************************************************************

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2)

---------------------- Link-state routing protocols ----------------------------------

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Link stejt ruting protokoli (Link state routing protocols)

In contrast to distance vector routing protocol operation, a router configured with a link-state

routing protocol can create a "complete view" or topology of the network by gathering information

from all of the other routers. To continue our analogy of sign posts, using a link-state routing

protocol is like having a complete map of the network topology. The sign posts along the way from

source to destination are not necessary, because all link-state routers are using an identical "map" of

the network. A link-state router uses the link-state information to create a topology map and to

select the best path to all destination networks in the topology.

Link-state protocols work best in situations where:

The network design is hierarchical, usually occurring in large networks.

The administrators have a good knowledge of the implemented link-state routing protocol.

Fast convergence of the network is crucial.

Link-state routing protocols are like using a map.

With a map, you can see all of the potential routes and determine your own preferred path.

Link-state routing protocols are more like a road map because they create a topological map of the

network and each router uses this map to determine the shortest path to each network.

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Svaki Ruter na koji radi Link-State algoritam radi sledeće:

**************************************************************************

1. Each router learns about its own links, its own directly connected networks. This is done by

detecting that an interface is in the up state.

2. Each router is responsible for meeting its neighbors on directly connected networks.

Routers with link-state routing protocols use a Hello protocol to discover any neighbors on its links.

3. Each router builds a Link-State Packet (LSP) containing the state of each directly connected link.

This is done by recording all the pertinent information about each neighbor, including neighbor ID,

link type, and bandwidth.

4. Each router floods the LSP to all neighbors, who then store all LSPs received in a database.

Neighbors then flood the LSPs to their neighbors until all routers in the area have received the LSPs.

Each router stores a copy of each LSP received from its neighbors in a local database.

An LSP only needs to be sent:

- During initial startup of the router or of the routing protocol process on that router

- Whenever there is a change in the topology, including a link going down or coming up, or a

neighbor adjacency being established or broken.

5. Each router uses the database to construct a complete map of the topology and computes the best

path to each destination network.

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Postoji nekoliko prednosti Link State protokola u odnosu na Distance Vektor Ruting Protokla

1. Builds a Topological Map

Link-state routing protocols create a topological map, or SPF tree of the network topology. Routers

implementing a distance vector routing protocol only have a list of networks, which includes the cost

(distance) and next-hop routers (direction) to those networks. Using the SPF tree, each router can

independently determine the shortest path to every network.

2. Fast Convergence

When receiving a Link-state Packet (LSP), link-state routing protocols immediately flood the LSP

out all interfaces except for the interface from which the LSP was received.

3. Event-driven Updates

After the initial flooding of LSPs, link-state routing protocols only send out an LSP when there is a

change in the topology.

4. Hierarchical Design

Link-state routing protocols such as OSPF and IS-IS use the concept of areas. Multiple areas create

a hierarchical design to networks, allowing for better route aggregation (summarization) and the

isolation of routing issues within an area.

Suma Sumaru ili ti Summary:

The link-state process can be summarized as follows:

1. Each router learns about its own directly connected networks.

2. Each router is responsible for "saying hello" to its neighbors on directly connected networks.

3. Each router builds a Link-State Packet (LSP) containing the state of each directly connected link.

4. Each router floods the LSP to all neighbors, who then store all LSPs received in a database.

5. Each router uses the database to construct a complete map of the topology and computes the best

path to each destination network.

--------------------------------------------------------------------------------------------------------------

Dinamički protokoli za rutiranje

**********************************************

Ruting Protokoli:

***********************************************

1. RIP

- Classful Routing Protocol

- Distance Vector Routing Protocol

*************************************************

Routing Information Protocol (RIP) has the following key characteristics:

- Hop count is used as the metric for path selection.

- If the hop count for a network is greater than 15, RIP cannot supply a route to that network.

- Routing updates are broadcast or multicast every 30 seconds, by default.

--------------------------------------

RIP Timers

***************

1. Invalid

2. Flush

3. Holddown

1. Invalid Timer - If an update has not been received to refresh an existing route after 180 seconds

(the default), the route is marked as invalid by setting the metric to 16. The route is retained in the

routing table until the flush timer expires.

2. Flush Timer - By default, the flush timer is set for 240 seconds, which is 60 seconds longer than the

invalid timer. When the flush timer expires, the route is removed from the routing table.

3. Holddown Timer - This timer stabilizes routing information and helps prevent routing loops during

periods when the topology is converging on new information. Once a route is marked as

unreachable, it must stay in holddown long enough for all routers in the topology to learn about the

unreachable network. By default, the holddown timer is set for 180 seconds.

--------------------------------------

RIP_JITTER,

*****************

- subtracts a variable amount of time to the update interval for each router in the network. This

random jitter, or variable amount of time, ranges from 0% to 15% of the specified update interval. In

this way, the update interval varies randomly in a range from 25 to 30 seconds for the default 30-

second interval.

KOnfiguarcije RIPv1:

***************************

Sintaksa je:

Router(config-router)#network directly-connected-classful-network-address

Password:cisco

R3>enable

Password: class

R3#configure terminal

R3(config)#router RIP (gasi se RIP komandom: no router rip)

R3(config-router)#network 192.168.3.0



R3(config-router)#end

znači ruter R3 je povezan na 3 mreže i to Serial 0/0/1 na 192.168.3.0, sa Serial0/0/0 na 192.168.5.0,

sa FE0/0 na 192.168.4.0. I ukljucena je automacka sumarizacija na klasnu granicu jer se informacije u

RIPv1 prenose bez subnet maske, pa mora da se nekako podrazumeva, pa stim su svi /24, odnosno

mreže klase C. To se zove Automacka Sumarizacije i ona se kod RIPv2 po defaultu ukljucena ali se za

razliku pd RIPv1 može isključiti, i postoji razlika u odnsu na Automacku Sumarizaciju i SuperNet, jer

Automacku Sumarizacija svodi samo na klasne granice na SuperNet samo obuhvata željene mreže.

Krakta napomena:

If you enter a subnet address, the IOS automatically converts it to a classful network address. For

example, if you enter the command network 192.168.1.32, the router will convert it to network

192.168.1.0.

--------------------------------------------------------------------------------------------------

1. Konfigurisanje pasivnog interfejsa - da se ne bi slali rip updat-ovi za džabe

**********************************************************************************

*****************

#passive-interface interface-type interface-number

This command stops routing updates out the specified interface. However, the network that the

specified interface belongs to will still be advertised in routing updates that are sent out other

interfaces.

Sintaksa:

Router(config-router)#passive-interface interface-type interface-number

Primer:

Router(config)# router rip

Router(config-router)#passive-interface fa0/0

2.Slanje (statičke) default rute kroz RIP.

**************************************************

Default-information originate command specify that this router is to originate default information, by

propagating the static default route in RIP updates.

Primer:

Router(config)# router rip

Router(config-router)#default-information originate

3. Redistribucija statiče rute u rip-u

*************************************************

Redistribution involves taking the routes from one routing source and sending those routes to

another routing source.

Sintaska:

R2(config)# router rip

R2(config-router)#redistribute static

--------------------------------------------------------------------------------------------------------------

Show naredbe koje se korste uz RIP:

*************************************************

#show ip rip database

*****************************

- This command shows all RIP routes learned by Router, whether or not the RIP route is installed in

the routing table.

#show ip route 172.16.1.0

************************************

- The show ip route 172.16.1.0 command reveals that the distance is 0 for that directly connected

route. Jer nam show ip route command displays the directly connected networks with no

information about the AD value.

Troubleshooting komande:

**************************************

- show ip route,

- show ip protocols,

- debug ip rip (no debug ip rip or simply undebug all),

- show ip interface brief

Rules for Processing RIPv1 Updates

**********************************************************

The following two rules govern RIPv1 updates:

If a routing update and the interface on which it is received belong to the same major network, the

subnet mask of the interface is applied to the network in the routing update.

If a routing update and the interface on which it is received belong to different major networks, the

classful subnet mask of the network is applied to the network in the routing update.

Rezime (Summary)

*****************************

RIP uses hop count for its metric, with a metric of 16 hops meaning that route is unreachable. As a

result, RIP can only be used in networks where there are no more than fifteen routers between any

two networks.

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

***********************************************

2. RIP v2

- Classless Routing Protocol


*************************************************

RIPv2 is actually an enhancement of RIPv1's features and extensions rather than an entirely new

protocol. Some of these enhanced features include:

- Next-hop addresses included in the routing updates

- Use of multicast addresses in sending updates

- Authentication option available

Like RIPv1, RIPv2 is a distance vector routing protocol. Both versions of RIP share the following

features and limitations:

- Use of holddown and other timers to help prevent routing loops.

- Use of split horizon or split horizon with poison reverse to also help prevent routing loops.

- Use of triggered updates when there is a change in the topology for faster convergence.

- Maximum hop count limit of 15 hops, with the hop count of 16 signifying an unreachable network.

Rip verzija 1 šalje update verzije 1 a prima update i verzije 1 i verzije 2 (šta je višak u update-u iz

verzije 2 on odmbaci).

Rip verzija 2 šalje update-ove verzije 2 i prima smao update-ove verzije 2.

--------------------------------------------------------------------------------------------------------------

Konfiguracije Ripv2

********************************

1. Redistribucija statiče rute u rip-u

***********************************************


R2(config-router)#redistribute static

2. Podešavanje da bude Ripv2 (po default-u je version 1)

***************************************************************************


R2(config-router)#version 2

3. Vraćanje da bude Ripv1

***********************************************


R2(config-router)#version 1 ili no version

4. Isključivanje automacke sumarizacije

****************************************************


R2(config-router)#version 2

R2(config-router)#no auto-summary

Summary - Objedinjeno

R1# configure terminal


R1(config-router)# no auto-summary

R1(config-router)# version 2

R1(config-router)# network 1.0.0.0

R1(config-router)# network 172.16.0.0

R1(config-router)# end

Autentifikacija RIPv2 (Authentication )

**************************************************

Metoda 1: Plain Text Authentication

**************************************************

key chain kal

****

!--- Name a key chain. A key chain may contain more than one key for added security.

!--- It need not be identical on the remote router.

key 1

***

!--- This is the Identification number of an authentication key on a key chain.

!--- It need not be identical on the remote router.

key-string 234

******

!--- The actual password or key-string.

!--- It needs to be identical to the key-string on the remote router.

interface Serial0

ip address 141.108.0.10 255.255.255.252

ip rip authentication key-chain kal

*****

!--- Enables authentication on the interface and configures

!--- the key chain that will be used.

router rip

version 2

network 141.108.0.0

network 70.0.0.0

---- Primer1 :


R1(config)# key chain RIP

R1(config-keychain)# key 1

R1(config-keychain-key)# key-string RGjtl5ANYa

R1(config-keychain-key)# end

- The key chain name, “RIP”, is user-defined and can be whatever you want it to be. It does not need

to be the same on both routers.

- The identifier number of the authentication key, “key 1″, does not need to be identical UNLESS you

are using MD5 authentication.

- The key string, “key-string RGjtl5ANYa”, is the actual password. It does, of course, need to match on

both sides.


R1(config)# interface serial 0/0

R1(config-if)# ip rip authentication key-chain RIP

R1(config-if)# end

---- Primer 2 sa show naredbom:

R2#configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

R2(config)#key chain RIP

R2(config-keychain)#key 1

R2(config-keychain-key)#key-string CISCO

R2(config-keychain-key)#end

R2#

R2#show key chain

Key-chain RIP:

key 1 -- text "CISCO"

accept lifetime (always valid) - (always valid) [valid now]

send lifetime (always valid) - (always valid) [valid now]

R2#

----------------------------------------------------------------------------------

Metoda 2: MD5 Authentication

***************************************

key chain kal

!--- Need not be identical on the remote router.

key 1

!--- Needs to be identical on remote router.

key-string 234

!--- Needs to be identical to the key-string on the remote router.

interface Serial0

ip address 141.108.0.10 255.255.255.252

ip rip authentication mode md5 (no ip rip authentication mode md5 - da se vrati na staro)

!--- Specifies the type of authentication used

!--- in RIPv2 packets.

!--- Needs to be identical on remote router.

!-- To restore clear text authentication, use the no form of this command.

ip rip authentication key-chain kal

Primer:


R1(config)# key chain RIP






R1(config-if)# ip rip authentication mode md5

R1(config-if)# end

--------------------------------------------------------------------------------------------------------------

Možda ima još koji način za autentifikaciju na RIPv2 (na RIPv1 ne postoji ta opcija)

— Interface command: ip rip authentication mode md5

— Interface command: no ip rip authentication mode md5

Set the interface with RIPv2 MD5 authentication.

— Interface command: ip rip authentication mode text

— Interface command: no ip rip authentication mode text

Set the interface with RIPv2 simple password authentication.

— Interface command: ip rip authentication string "string"

— Interface command: no ip rip authentication string "string"

RIP version 2 has simple text authentication. This command sets authentication string. The string

must be shorter than 16 characters.

— Interface command: ip rip authentication key-chain "key-chain"

— Interface command: no ip rip authentication key-chain "key-chain"

--------------------------------------------------------------------------------------------------------------

***********************************************

3. IGRP

-


*************************************************

Interior Gateway Routing Protocol (IGRP) is a proprietary protocol developed by Cisco. IGRP has the

following key design characteristics:

Bandwidth, delay, load and reliability are used to create a composite metric.

Routing updates are broadcast every 90 seconds, by default.

IGRP is the predecessor of EIGRP and is now obsolete.

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

***********************************************

4. EIGRP



*************************************************

Enhanced IGRP (EIGRP) is a Cisco proprietary distance vector routing protocol. EIGRP has these key

characteristics:

It can perform unequal cost load balancing.

It uses Diffusing Update Algorithm (DUAL) to calculate the shortest path.

There are no periodic updates as with RIP and IGRP. Routing updates are sent only when there is a

change in the topology.

---------------------------------------------------------------------------------

Prednosi EIGRP-a U odnosu na RIP (RIPv1 and RIPv2) i IGRP.

These features include:

- Reliable Transport Protocol (RTP)

- Bounded Updates

- Diffusing Update Algorithm (DUAL)

- Establishing Adjacencies

- Neighbor and Topology Tables

Although EIGRP may act like a link-state routing protocol, it is still a distance vector routing protocol.

-----------------------------------------------------------------------------------------

Reliable Transport Protocol (RTP) is the protocol used by EIGRP for the delivery and reception of

EIGRP packets.

RTP can send packets either as a unicast or a multicast.

Multicast EIGRP packets use the reserved multicast address of 224.0.0.10.

Tipovi EIGRP paketa (eigrp paketi)

**********************************************

*** Hello packets ***

- are used by EIGRP to discover neighbors and to form adjacencies with those neighbors. EIGRP

hello packets are multicasts and use unreliable delivery.

On most networks EIGRP Hello packets are sent every 5 seconds. On multipoint nonbroadcast

multiaccess networks (NBMA) such as X.25, Frame Relay, and ATM interfaces with access links of T1

(1.544 Mbps) or slower, Hellos are unicast every 60 seconds.

Holdtime tells the router the maximum time the router should wait to receive the next Hello before

declaring that neighbor as unreachable.

By default, the hold time is three times the Hello interval, or 15 seconds on most networks and 180

seconds on low speed NBMA networks.

If the hold time expires, EIGRP will declare the route as down and DUAL will search for a new path by

sending out queries.

*** Update packets ***

- are used by EIGRP to propagate routing information. Unlike RIP, EIGRP does not send periodic

updates. Update packets are sent only when necessary. EIGRP updates contain only the routing

information needed and are sent only to those routers that require it. EIGRP update packets use

reliable delivery. Update packets are sent as a multicast when required by multiple routers, or as a

unicast when required by only a single router. In the figure, because the links are point-to-point, the

updates are sent as unicasts.

The term partial means that the update only includes information about the route changes. EIGRP

sends these incremental updates when the state of a destination changes, instead of sending the

entire contents of the routing table.

The term bounded refers to the propagation of partial updates sent only to those routers that are

affected by the change. The partial update is automatically "bounded" so that only those routers that

need the information are updated.

By sending only the routing information that is needed and only to those routers that need it, EIGRP

minimizes the bandwidth required to send EIGRP packets.

*** Acknowledgement (ACK) packets ***

- are sent by EIGRP when reliable delivery is used. RTP uses reliable delivery for EIGRP update,

query, and reply packets. EIGRP acknowledgement packets contain a nonzero acknowledgment

number and always are sent by using a unicast address.

*** Query and reply packets ***

- are used by DUAL when searching for networks and other tasks. Queries and replies use reliable

delivery. Queries use multicast, whereas replies are always sent as unicast.

Diffusing Update Algorithm (DUAL) is the convergence algorithm used by EIGRP instead of the

Bellman-Ford or Ford Fulkerson algorithms used by other distance vector routing protocols, like RIP.

The decision process for all route computations is done by the DUAL

- Finite State Machine. In general terms, a finite state machine (FSM) is a model of behavior

composed of a finite number of states, transitions between those states, and events or actions that

create the transitions.

DUAL maintains a list of backup routes it has already determined to be loop-free. If the primary route

in the routing table fails, the best backup route is immediately added to the routing table.

Autonomni sistem - Autonomous System

*****************************************************

An autonomous system (AS) is a collection of networks under the administrative control of a single

entity that presents a common routing policy to the Internet.

Null0 - nula interfejs

**************************

EIGRP automatically includes a null0 summary route as a child route whenever both of following

conditions exist:

- There is at least one subnet that was learned via EIGRP.

- Automatic summarization is enabled.

We will see that the null0 summary route is removed when automatic summary is disabled.

--------------------------------------------------------------------------------------------------------------

1. Konfiguracija EIGRP-a

********************************

Redistribucija Statičke rute (obično default rute)

****************************************************************

The redistribute static command tells EIGRP to include this static route in its EIGRP updates to other

routers.

Način 1:

Router(config)#ip route 0.0.0.0 0.0.0.0 serial0/0/1

Router(config)#router eigrp 1

Router(config-router)#redistribute static

Način 2:

Router(config)#ip default-network 172.31.0.0


Router(config-router)#redistribute static

Način 3:

ISP# configure terminal

ISP(config)# ip route 0.0.0.0 0.0.0.0 loopback 0

ISP(config)# router ospf 1

ISP(config-router)# default-information originate

ISP(config-router)# end

ISP#

------------------------------------------------------------------------------------------

2. Iskoristivos bandvida linka u procentima, ograničavanje (bandwith utilization)

***************************************************************************

Router(config-if)#ip bandwidth-percent eigrp as-number percent

Primer:

Router(config)#interface serial 0/1/0

Router(config-if)#bandwith 64

Router(config-if)#ip bandwidth-percent eigrp 1 50 (znači 50% bandwitha maksimalno može EIGRP da

kostisi, bandwitha podesenog ne stvarnog, ako nisu isti)

EIGRP will never use more the 32kbps of the link's bandwidth for EIGRP packet traffic.

--------------------------------------------------------------------------------------------------------------

3. Podesavanje intervala slanja Hallo paketa i Hold time-a

*************************************************************************

Router(config-if)#ip hello-interval eigrp as-number seconds

If you change the hello interval, make sure that you also change the hold time to a value equal to or

greater than the hello interval.

Otherwise, neighbor adjacency will go down after the hold time expires and before the next hello

interval.

The command to configure a different hold time is:

Router(config-if)#ip hold-time eigrp as-number seconds

Router(config)#interface serial 0/1/0

Router(config)#ip hello-interval eigrp 1 60 (može od 1 do 65,535)

Router(config)#ip hold-time eigrp 1 180 (može od 1 do 65,535)

Teoriski reziime:

***********************

- EIGRP used PDMs (Protocol Dependent Modules) giving it the capability to support different Layer 3

protocols including IP, IPX and AppleTalk.

- EIGRP uses RTP (Reliable Transport Protocol) as the Transport layer protocol for the delivery of

EIGRP packets.

- EIGRP uses reliable delivery for EIGRP updates, queries and replies; and uses unreliable delivery for

EIGRP hellos and acknowledgments. Reliable RTP means an EIGRP acknowledgment must be

returned.

- The successor is a neighboring router that is used to forward the packet using the least-cost route

to the destination network.

- Feasible distance (FD) is the lowest calculated metric to reach the destination network through the

successor.

- A feasible successor (FS) is a neighbor who has a loop-free backup path to the same network as the

successor, and also meets the feasibility condition.

- The feasibility condition (FC) is met when a neighbor's reported distance (RD) to a network is less

than the local router's feasible distance to the same destination network. The reported distance is

simply an EIGRP neighbor's feasible distance to the destination network.

-------------------------------------------------------------------------------------------------

Metrika kod EIGRP-a

******************************

By default, K1 and K3 are set to 1, and K2, K4, and K5 are set to 0.

The result is that only the bandwidth and delay values are used

Podesavanje parametara:

************************************

Router(config-router)#metric weights tos k1 k2 k3 k4 k5

The tos (Type of Service) value is left over from IGRP and was never implemented. The tos value is

always set to 0.

EIGRP Metric = 256*([K1*Bw + K2*Bw/(256-Load) + K3*Delay]*[K5/(Reliability + K4)])

256 is because EIGRP metric is 256 x IGRP metric

BW is 10^7 / Link BW in Kb (note this is of the slowest link in the path)

K values are the weights. So default is K1 = 1 , K2 = 0 , K3 = 1 , K4 = 0 , K5 = 0

pa onda ispadne: EIGRP Metric = 256*(Bw + Delay)

The smallest Kb value of any link on the best path from your diagram is 10000Kb.

------------------------------------------------------

Bandwith

*************

-- Statični podatak --

The bandwidth metric (1544 Kbit) is a static value used by some routing protocols such as EIGRP and

OSPF to calculate their routing metric. The bandwidth is displayed in Kbit (kilobits). Most serial

interfaces use the default bandwidth value of 1544 Kbit or 1,544,000 bps (1.544 Mbps). This is the

bandwidth of a T1 connection.

The value of the bandwidth may or may not reflect the actual physical bandwidth of the interface.

The bandwidth command only modifies the bandwidth metric used by routing protocols such as

EIGRP and OSPF.

Hoću reći da:

--- Modifying the bandwidth value does not change the actual bandwidth of the link. ---

provera se sa show ip interface "serial 0/0/0"

... BW 1544 Kbit...

Konfiguriše se sa:

Router(config-if)#bandwidth kilobits

Delay

********

-- Statični podatak --

Default value is 20,000 microseconds for Serial interfaces (T1) and 100 microseconds for FastEthernet

interfaces.

FastEthernet 100 microseconds

Ethernet 1.000 microseconds

T1 (Serial Default) 20.000 microseconds

512K 20.000 microseconds

56K 20.000 microseconds


...DLY 20000...

Reliability

*************

-- Dinamični podatak --

Reliability is measured dynamically with a value between 0 and 255, with 1 being a minimally reliable

link and 255 one hundred percent reliable.

Reliability is calculated on a 5-minute weighted average to avoid the sudden impact of high (or low)

error rates.

255/255 would be 100 percent reliable, whereas a link of 234/255 would be 91.8 percent reliable.


... reliability 255/255...

Remember: By default, EIGRP does not use reliability in its metric calculation.

Load

************

-- Dinamični podatak --

Load (load) reflects the amount of traffic utilizing the link. Like reliability, load is measured

dynamically with a value between 0 and 255.

Similar to reliability, load is expressed as a fraction of 255.

However, in this case a lower load value is more desirable because it indicates less load on the link.

1/255 would be a minimally loaded link.

40/255 is a link at 16 percent capacity, and

255/255 would be a link that is 100 percent saturated.

Load is displayed as both an outbound, or transmit, load value (txload) and an inbound, or receive,

load value (rxload).

This value is calculated on a 5-minute weighted average to avoid the sudden impact of high (or low)

channel usage.


... txload 1/255, rxload 1/255...

txload - izlazni saobraćaj (tj količina izlaznog saobraćaja)

rxload - dolazni saobraćaj

Remember: By default, EIGRP does not use load in its metric calculation.

-------------------------------------------------------------------------------------------------------------

DUAL uses several terms which will be discussed in more detail throughout this section:

- Successor

*****************

A successor is a neighboring router that is used for packet forwarding and is the least-cost route to

the destination network.

The IP address of a successor is shown in a routing table entry right after the word via.

D 192.168.1.0/24 [90/3014400] via 192.168.10.10, 00:00:31, Serial0/0/1

192.168.10.10 - je Successor.

- Feasible Distance (FD)

*********************************

Feasible distance (FD) is the lowest calculated metric to reach the destination network.

As with other routing protocols this is also known as the metric for the route.

D 192.168.1.0/24 [90/3014400] via 192.168.10.10, 00:00:31, Serial0/0/1

3014400 - je Feasible Distance

- Feasible Successor (FS)

***********************************

A feasible successor (FS) is a neighbor who has a loop-free backup path to the same network as the

successor by satisfying the feasibility condition.

- Reported Distance (RD) or Advertised Distance (AD)

************************************************************************

- Feasible Condition or Feasibility Condition (FC)

******************************************************************

The feasibility condition (FC) is met when a neighbor's reported distance (RD) to a network is less

than the local router's feasible distance to the same destination network. The reported distance or

advertised distance is simply an EIGRP neighbor's feasible distance to the same destination network.

The reported distance is the metric that a router reports to a neighbor about its own cost to that

network.

--------------------------------------------------------------------------------------------------------------

Konfiguracije EIGRP-a

******************************

Router(config)#router eigrp "autonomous-system" (between 1 and 65535)

Although EIGRP refers to the parameter as an "autonomous-system" number, it actually functions as

a process ID.

This number is not associated with an autonomous system number discussed previously and can be

assigned any 16-bit value.

Primer: Router(config)#router eigrp 1

Both EIGRP and OSPF can support multiple instances of each routing protocol, although this type of

multiple routing protocol implementation is not usually needed or recommended.

Remember, the process ID must be the same on all routers for EIGRP to establish neighbor

adjacencies and share routing information.

Komanda: eigrp log-neighbor-changes

***************************************************

To enable the logging of EIGRP neighbor adjacency changes, use the:

#eigrp log-neighbor-changes - command in router configuration mode. To turn off this function, use

the no form of this command.

eigrp log-neighbor-changes ili no eigrp log-neighbor-changes

The eigrp log-neighbor-changes command is enabled by default;

only the no form of the command appears in the running configuration.

hostname(config)# router eigrp 100

hostname(config-router)# no eigrp log-neighbor-changes

This command turns off the neighbor logging when any neigbor resets or changes or goes down.

You should always turn it on to see which neighor has gone down and that makes troubleshooting

easier.

Komanda: eigrp log-neighbor-warnings

***************************************************

To enable the logging of EIGRP neighbor warning messages, use the

#eigrp log-neighbor-warnings - command in router configuration mode. To turn off this function, use

the no form of this command.

eigrp log-neighbor-warnings [seconds] ili no eigrp log-neighbor-warnings

Primer:


hostname(config-router)# eigrp log-neighbor-warnings 300

Komanda: eigrp router-id

*********************************

To specify router ID used by the EIGRP routing process, use the

#eigrp router-id - command in router configuration mode. To restore the default value, use the no

form of this command.

eigrp router-id ip-addr ili no eigrp router-id [ip-addr]

Primer:


hostname(config-router)# eigrp router-id 172.16.1.3

Podesavanje manulene sumarizacije (manualna sumariacija kod EIGRP-a):

**********************************************************************************

**************

Router(config)#interface serial0/0/1

Router(config-if)#ip summary-address eigrp as-number network-address subnet-mask

Router(config-if)#ip summary-address eigrp 1 192-168.0.0 255.255.252.0

---------------------------------

Zadavanje mreža:

Način 1, classful:

**********************

Router(config-router)#network "network-address"

The network-address is the classful network address for this interface.

Primer: Router(config-router)#network 172.16.0.0

Način 2, A ako treba može i sa subnetom, samo ne klasično nego preko wildcard:

**********************************************************************************

*********************

Router(config-router)#network network-address [wildcard-mask]

Primer: R2(config-router)#network 192.168.10.8 0.0.0.3

Način 3, Nije baš najpreporučljivije pošto neke verzije IOS-a će ovu subnet masku pretoriti u wild card

automacki a kod nekih će javiti grešku, mada može se pokušati, ne plaća se pokušaj pa zašto da ne,

mislim ovo je jednostava broj, može biti i malo težih:

**********************************************************************************

**************************

R2(config-router)#network 192.168.10.8 255.255.255.252

--------------------------------------------------------------------------------------------------------------------------------------

---------------------------------------------------------------------------------

Null0 summary routes (Null0 sumarna ruta) - So by default, EIGRP uses the Null0 interface to discard

any packets that match the parent route but do not match any of the child routes.

Null0 interface (Null0 interfejs, nula interfejs) - is simply a route to nowhere, commonly known as

"the bit bucket."

A sad, sečka! Na sve su mislili kod ovog protokola, i sad i kad je classless behavior na snazi, kod

EIGRP-a traženje se ponaša kao classful:

**********************************************************************************

**********************

You might think that if we configure classless routing behavior with the ip classless command, EIGRP

would not discard that packet but would continue looking for a default or supernet route.

However, the EIGRP Null0 summary route is a child route that will match any possible packets of the

parent route that do not match another child route. Even with classless routing behavior, ip classless,

where you would expect the route lookup process to check for supernets and default routes, EIGRP

will use the Null0 summary route and discard the packet because this route will match any packets of

the parent that do not have a child route.

Regardless of whether classful or classless routing behavior is being used, the null0 summary will be

used and therefore denying the use of any supernet or default route.

Primer:

192.168.10.0/24 is a variably subnetted, 3 subnets, 2 masks

D 192.168.10.0/24 is a summary, 00:45:09, Null0

C 192.168.10.4/30 is directly connected, Serial0/0/1

...

EIGRP automatically includes a null0 summary route as a child route whenever both of following

conditions exist:

- There is at least one subnet that was learned via EIGRP.

- Automatic summarization is enabled.

Like RIP, EIGRP automatically summarizes at major network boundaries.

You may have already noticed in the #show run output - that EIGRP, by default, uses the auto-

summary command.

Ovakvo ponašanje se može promeniti, tj isključiti automacka sumarizacija kod EIGRP-a tako što:


Router(config-router)#no auto-summary

Show naredbe kod EIGRP-a:

***************************************

#show ip eigrp neighbors

- Use the show ip eigrp neighbors command to view the neighbor table and verify that EIGRP has

established an adjacency with its neighbors.

The output from the show ip eigrp neighbor command includes:

- H column - Lists the neighbors in the order they were learned.

- Address - The IP address of the neighbor.

- Interface - The local interface on which this Hello packet was received.

- Hold - The current hold time. Whenever a Hello packet is received, this value is reset to the

maximum hold time for that interface and then counts down to zero. If zero is reached, the neighbor

is considered "down".

- Uptime - Amount of time since this neighbor was added to the neighbor table.

- SRTT (Smooth Round Trip Timer) and RTO (Retransmit Interval) - Used by RTP to manage reliable

EIGRP packets.

- Queue Count - Should always be zero. If more than zero, then EIGRP packets are waiting to be sent.

- Sequence Number - Used to track updates, queries, and reply packets.

--------------------------------------------------------------

#show ip eigrp topology ili #show ip eigrp topology [network]

The topology table lists all successors and feasible successors that DUAL has calculated to

destination networks.

1. P 192.168.1.0/24, 1 successor, FD is 3014400

2. via 192.168.10.10 (3014400/28160), Serial0/0/1

3. via 172.16.3.1 (41026560/2172416), Serial0/0/0

1. Prvi red (P 192.168.1.0/24, 1 successor, FD is 3014400):

******************************************************************************

P - This route is in the passive state. When DUAL is not performing its diffusing computations to

determine a path for a network, the route will be in a stable mode, known as the passive state. If

DUAL is recalculating or searching for a new path, the route will be in an active state. All routes in the

topology table should be in the passive state for a stable routing domain. DUAL will display an A if the

route is "Active,".

Primer: #R2#show ip eigrp topology 192.168.1.0

1. P 192.168.1.0/24, 1 successor, FD is 3014400

2. via 192.168.10.10 (3014400/28160), Serial0/0/1

3. via 172.16.3.1 (41026560/2172416), Serial0/0/0

192.168.1.0/24 - This is the destination network that is also found in the routing table.

1 successors - This shows the number of successors (sakcesora) for this network. If there are multiple

equal cost paths to this network, there will be multiple successors.

FD (fizibal distanc) is 3014400 - This is the feasible distance, the EIGRP metric to reach the

destination network.

E sad, drugi red ( via 192.168.10.10 (3014400/28160), Serial0/0/1):

**********************************************************************************

****

via 192.168.10.10 - This is the next-hop address of the successor, R3. This address is shown in the

routing table.

3014400 - This is the feasible distance to 192.168.1.0/24. It is the metric shown in the routing table.

28160 - This is the reported distance of the successor and is R3's cost to reach this network.

Serial0/0/1 - This is the outbound interface used to reach this network, also shown in the routing

table.

I treći deo (via 172.16.3.1 (41026560/2172416), Serial0/0/0):

*********************************************************************************

via 172.16.3.1 - This is the next-hop address of the feasible successor, R1.

41026560 - This would be R2's new feasible distance to 192.168.1.0/24 if R1 became the new

successor.

2172416 - This is the reported distance of the feasible successor or R1's metric to reach this network.

--- This value, RD, must be less than the current FD of 3014400 to meet the feasibility condition. ---

Serial0/0/0 - This is the outbound interface used to reach feasible successor, if this router becomes

the successor.

Znači poenta je da bi bilo ovako 2 rute, tj jedna koja se korsisti i druga backup ruta, potrebno je da

druga brojka u backup ruti bude MANJA od prve brojke u ruti koja je sakcesor, u ovom slučaju to je

tako jer je 2172416 manje od 3014400. A da to nije slučaj, rita ne bi posedovala fizibal sakcesora tj ne

bi postojala backup ruta. Sve rute se mogu videti komandom #show ip eigrp topology all-links.

----------------------------------------------------------------------------------------------------------

#show ip eigrp topology all-links

The show ip eigrp topology all-links command shows all possible paths to a network including

successors, feasible successors, and even those routes that are not feasible successors

Ovde se vide sve moguće rute.

-----------------------------------------------------------------------------------------------

#debug eigrp fsm

turn on DUAL debugging with the debug eigrp fsm command.

Autentifikacija EIGRP

***************************

Authentication does not encrypt the router's routing table.

Primer 1:


R1(config)# router eigrp 42

R1(config-router)# no auto-summary

R1(config-router)# network 172.16.12.1 0.0.0.0

R1(config-router)# network 1.1.1.1 0.0.0.0

R1(config-router)# end


R1(config)# key chain EIGRP






R1(config-if)# ip authentication key-chain eigrp 42 EIGRP

R1(config-if)#

R1(config-if)# ip authentication mode eigrp 42 md5

R1(config-if)# end

Verifying EIGRP authentication - using “debug eigrp packets”.

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

***********************************************

5. OSPF - Open Shortest Path First (AD = 110)


- Link-state routing protocols

*************************************************

“Each router’s OSPF router ID should be the IP address of its FastEthernet 0/0 interface”

“The OSPF router ID is a 32-bit IP address selected at the start of the OSPF process. The highest IP

address configured on the router is the router ID. If a loopback address is configured, it is the router

ID. In the case of multiple loopback addresses, the highest loopback address is the router ID. Once

the router ID is elected, it does not change unless OSPF restarts or is manually changed with the

router-id command.”

OSPF routers do flood their own link-states every 30 minutes. This is known as a paranoid update.

Open Shortest Path First (OSPF ) is a link-state routing protocol that was developed as a replacement

for the distance vector routing protocol RIP.

The Cisco IOS uses bandwidth as the OSPF cost metric.

-------------------------------------------------------------------------------------------------------------

Vrste Paketa kod OSPF-a

***************************************

1. Hello - Hello packets are used to establish and maintain adjacency with other OSPF routers.

Hello packets are used to:

- Discover OSPF neighbors and establish neighbor adjacencies.

- Advertise parameters on which two routers must agree to become neighbors.

- Elect the Designated Router (DR) and Backup Designated Router (BDR) on multiaccess networks like

Ethernet and Frame Relay.

Before two routers can form an OSPF neighbor adjacency, they must agree on three values:

- a) Hello interval,

- b) Dead interval, and

- c) network type.

a) The OSPF Hello interval indicates how often an OSPF router transmits its Hello packets. By default,

OSPF Hello packets are sent every 10 seconds on multiaccess and point-to-point segments and every

30 seconds on non-broadcast multiaccess (NBMA) segments (Frame Relay, X.25, ATM).

In most cases, OSPF Hello packets are sent as multicast to an address reserved for ALLSPFRouters at

224.0.0.5. Using a multicast address allows a device to ignore the packet if its interface is not enabled

to accept OSPF packets.

b) The Dead interval is the period, expressed in seconds, that the router will wait to receive a Hello

packet before declaring the neighbor "down."

Cisco uses a default of four times the Hello interval.

For multiaccess and point-to-point segments, this period is 40 seconds.

For NBMA networks, the Dead interval is 120 seconds.

If the Dead interval expires before the routers receive a Hello packet, OSPF will remove that neighbor

from its link-state database.

The router floods the link-state information about the "down" neighbor out all OSPF enabled

interfaces.

2. DBD - The Database Description (DBD) packet contains an abbreviated list of the sending router's

link-state database and is used by receiving routers to check against the local link-state database.

3. LSR - Receiving routers can then request more information about any entry in the DBD by sending

a Link-State Request (LSR).

4. LSU - Link-State Update (LSU) packets are used to reply to LSRs as well as to announce new

information. LSUs contain seven different types of Link-State Advertisements (LSAs).

Link-state updates (LSUs) are the packets used for OSPF routing updates.

An LSU packet can contain 11 different types of Link-State Advertisements (LSAs), as shown in the

figure.

An LSU contains one or more LSAs and either term can be used to refer to link-state information

propagated by OSPF routers.

5. LSAck - When an LSU is received, the router sends a Link-State Acknowledgement (LSAck) to

confirm receipt of the LSU.

-----------------------------------------------------------------------------------------------------------

Razlika između process-id kod OSPF-a i kod EIGRP-a

**********************************************************************

- The process-id is locally significant, which means that it does not have to match other OSPF routers

in order to establish adjacencies with those neighbors.

- This differs from EIGRP. The EIGRP process ID or autonomous system number does need to match

for two EIGRP neighbors to become adjacent.

--------------------------------------------------------------------------------------------------------------

Router ID

****************

A router ID is simply an IP address.

Cisco routers derive the router ID based on three criteria and with the following precedence:

1. Use the IP address configured with the OSPF router-id command.

2. If the router-id is not configured, the router chooses highest IP address of any of its loopback

interfaces.

3. If no loopback interfaces are configured, the router chooses highest active IP address of any of its

physical interfaces.

The interface does not need to be enabled for OSPF, meaning that it does not need to be included in

one of the OSPF network commands.

However, the interface must be active - it must be in the up state.

-----------------------------------------------------------------------------------------------------------

Kad treba koristiti router-id komandu. Zbog specifičnosti pravila mora se dobro paziti kad se šta radi:

**********************************************************************************

**************************

Pošto vlada pravilo da:

The router ID is selected when OSPF is configured with its first OSPF network command. If the OSPF

router-id command or the loopback address is configured after the OSPF network command, the

router ID will be derived from the interface with the highest active IP address.

Onda je naknadno menjanje jedino moguće:

The router ID can be modified with the IP address from a subsequent OSPF router-id command by

reloading the router or by using the following command:

Router#clear ip ospf process

Primer:

R1# clear ip ospf process

Reset ALL OSPF processes? [no]:yes

R1#

Note: Modifying a router ID with a new loopback or physical interface IP address may require

reloading the router.

-------------------------------------------------------------------------------------------------------------

Problem sa nestabilnim linkom, interfejsom, tj flapping-om je donekle rešen pomoću Timera što se

vidi pomoću naredbe #show ip ospf:

A flapping link can cause OSPF routers in an area to constantly recalculate the SPF algorithm,

preventing proper convergence.

To minimize this problem, the router waits 5 seconds (5000 msecs) after receiving an LSU before

running the SPF algorithm. This is known as the SPF schedule delay.

In order to prevent a router from constantly running the SPF algorithm, there is an additional Hold

Time of 10 seconds (10000 msecs). The router waits 10 seconds after running the SPF algorithm

before rerunning the algorithm again.

--------------------------------------------------------------------------------------------------------------

Metrika kod OSPF-a

***************************

"A cost is associated with the output side of each router interface. This cost is configurable by the

system administrator. The lower the cost, the more likely the interface is to be used to forward data

traffic."

The Cisco IOS uses the cumulative bandwidths of the outgoing interfaces from the router to the

destination network as the cost value.

Reference bandwidth

****************************

FastEthernet or faster 1

Ethernet 10

E1 48

T1 64

128 kpps 781

64 kbps 1562

56 kbps 1785

The reference bandwidth can be modified to accommodate networks with links faster than

100,000,000 bps (100 Mbps) using the OSPF command #auto-cost reference-bandwidth.

When this command is necessary, it is recommended that it is used on all routers so the OSPF routing

metric remains consistent.

Primer:

R1(config)#router ospf 1

R1(config-router)#auto-cost reference-bandwidth 1000

The range of the reference bandwidth is 1 to 4,294,967.

The default is 100. The unit of measurement is Mbps.

Sad je računica:

Here are the calculations:

100000000/1544000 = 64

1000000000/1544000 = 647

--------------------------------------------------------------------------------------------------------------

Ethernet LANs are an example of a broadcast multiaccess network.

**********************************************************************************

*****

They are broadcast networks because all devices on the network see all broadcast frames. They are

multiaccess networks because there may be numerous hosts, printers, routers, and other devices

that are all members of the same network.

Point-to-point network there are only two devices on the network, one at each end.

--------------------------------------------------------------------------------------------------------------

OSPF definiše 5 tipova mreže a to su:

**************************************************

OSPF defines five network types:

Point-to-point

Broadcast Multiaccess

Nonbroadcast Multiaccess (NBMA)

Point-to-multipoint

Virtual links

NBMA and point-to-multi-point networks include Frame Relay, ATM, and X.25 networks. Virtual links

are a special type of link that can be used in multi-area OSPF.

--------------------------------------------------------------------------------------------------------------

DR i BDR selektivni proces kod OSPF-a

*******************************************************

DR/BDR elections do not occur in point-to-point networks.

Therefore, in a standard three-router topology, R1, R2, and R3 do not need to elect a DR and BDR,

because the links between these routers are not multiaccess networks.

Selekcije koji Router će biti DR a koji BDR se izvodi:

**********************************************************************

1. DR: Router with the highest OSPF interface priority.

2. BDR: Router with the second highest OSPF interface priority.

3. If OSPF interface priorities are equal, the highest router ID is used to break the tie.

State stavka (kolona) kod komande #show ip ospf neighbour

DROthers only form FULL adjacencies with the DR and BDR, but will still form a neighbor adjacency

with any DROthers that join the network.

This means that all DROther routers in the multiaccess network still receive Hello packets from all

other DROther routers.

When two DROther routers form a neighbor adjacency, the neighbor state is displayed as 2WAY.

When the DR is elected, it remains the DR until one of the following conditions occurs:

- The DR fails.

- The OSPF process on the DR fails.

- The multiaccess interface on the DR fails.

Ako hoćemo samoinicijativno da odredimo ili promenimo DR i BDR možemo uraditi jedno od sledećih

stvari a to je:

**********************************************************************************

*************************

- Boot up the DR first, followed by the BDR, and then boot all other routers, or

- Shut down the interface on all routers, followed by a no shutdown on the DR, then the BDR, and

then all other routers.

A najboilji način je preko OSPF prioriteta na interfejsima:

Router(config-if)#ip ospf priority {0 - 255}

A value of 0 makes the router ineligible to become a DR or BDR.

Primer:

R1(config)#interface fastEthernet0/0

R1(config-if)#ip ospf priority 255

R1(config-if)#end

--------------------------------------------------------------------------------------------------------------

Teoriski Rezime (Summary)

*************************************

OSPF does not use a Transport layer protocol, as OSPF packets are sent directly over IP.

For routers to become adjacent, their Hello interval, Dead interval, network types and subnet masks

must match

Opet naponea, bitno je:

Cisco routers derive the router ID based on three criteria and with the following precedence:

1. Use the IP address configured with the OSPF router-id command.

2. If the router-id is not configured, the router chooses highest IP address of any of its loopback

interfaces.

3. If no loopback interfaces are configured, the router chooses highest active IP address of any of its

physical interfaces.

--------------------------------------------------------------------------------------------------------------

*********************************

Konfiguracije OSPF-a

**********************************

Sintaksa:

**************

1. Pokretanje OSPF-a na ruteru:

R1(config)#router ospf process-id (process-id = od 1 do 65535)

Primer:


R1(config-router)#

--------------------------------------------------------------------

2. Uključivanje mreža u OSPF

*****************************************

Router(config-router)#network network-address wildcard-mask area area-id

--------------------------------------------------------------------

3. Podsetnik - konfiguracija LoopBack interfejsa

****************************************************************

Router(config)#interface loopback number

Router(config-if)#ip address ip-address subnet-mask

--------------------------------------------------------------------

4. Podesavanje router-id-a:

**********************************************

Router(config)#router ospf process-id

Router(config-router)#router-id ip-address

Primer isključivanje komande za menjanje router-id-a:


R1(config-router)#no router-id 10.4.4.4

Reload or use “clear ip ospf process” command, for this to take effect

R1(config-router)#end

R1# clear ip ospf process

Reset ALL OSPF processes? [no]:yes

R1#

--------------------------------------------------------------------

5. Podesavanje bandwitha odnosno metrike, imamo dva načina, možda ovaj drugi ima više prednosti,

tj dobar je kad nisu svi uređaji Cisoco ali moramo mi da računamo, ili pogledamo u tablicu, a kod

prvog Router računa:

**********************************************************************************

***************************

The ip ospf cost command is useful in multi-vendor environments where non-Cisco routers use a

metric other than bandwidth to calculate the OSPF costs.

5.1 Podsetnik - podesavanje bandwith-a na interfejsu

Router(config-if)#bandwidth bandwidth-kbps

I kad na primer napišemo:

Router(config-if)#bandwidth bandwidth 64

to je 64 = 64000 bps što znači da će metrika tj Cost: 1562 jer je 10 na 8 / 64000 bps = 1562. 10 na 8 je

100,000,000.

5.2. Ako hoćemo može i da direktno kažemo koliki je Cost za taj link, ako smo ga kojim slučajem sami

izračunali ili imamo gotov podatak:

Primer:

R1(config)#interface serial 0/0/0

R1(config-if)#ip ospf cost 1562

Tablica:

***********

bandwith 64 = 1526

bandwith 256 = 390

bandwith 128 = 781

Ako je potrebno da menjamo računicu, ili da na svim ruterima podesimo isto računanje (ako su ruteri

različiti, različiti proizvođača ili pak ako samo na različite načine računaju Cost po bandwith-u):

Sintaksa:

R1(config-router)#auto-cost reference-bandwidth ?

1-4294967 The reference bandwidth in terms of Mbits per second

The default value is equivalent to 100.

Notice that the value is expressed in Mbps.

R1(config-router)#auto-cost reference-bandwidth 10000

6. Ako je potrebno, menjanje default vrednosti za Hello i Dead Timer:

**********************************************************************************

*********

OSPF Hello and Dead intervals can be modified manually using the following interface commands:

Router(config-if)#ip ospf hello-interval "seconds"

Router(config-if)#ip ospf dead-interval "seconds"

The output that the Dead Time is counting down from 40 seconds.

By default, this value is refreshed every 10 seconds when R1 receives a Hello from the neighbor.

A rezultate podesavanje proveravamo sa #ip ospf interface serial 0/0/0:

OSPF requires that the Hello and Dead intervals match between two routers for them to become

adjacent. This differs from EIGRP where the Hello and Holddown timers do not need to match for

two routers to form an EIGRP adjacency.

--------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------

Osnovna konfiguracija OSPF-a:

******************************



ISP(config-router)# network 188.46.37.252 0.0.0.3 area 0



ISP#

--------------------------------------------------------------------------------

1. Slanje default statičke rute ostalim ruterima pod OSPF-om

*****************************************************************************

Advertise the 0.0.0.0/0 static default route to the other routers in the area.

R1(config-router)#default-information originate

Primer:

R1(config)#ip route 0.0.0.0 0.0.0.0 loopback1

R1(config)#

Use the default-information originate command to include the static route

in the OSPF updates that are sent from the R1 router.


R1(config-router)#default-information originate

R1(config-router)#

--------------------------------------------------------------------------------

2. Manuelno podešavanje Ruter ID-a:

************************************************



ISP(config-router)# router-id 10.10.10.1

Reload or use "clear ip ospf process" command, for this to take effect


ISP#

Note that IOS warned us that the router ID will not change until the OSPF process restarts (either

manually or via a router reload).

--------------------------------------------------------------------------------

3. Meeting the DR/BDR requirements, podesavanje DR i BDR-a kod OSPF-a

Menjanje OSPF prioriteta na interfejsima

**********************************************************************************

**************

First, to ensure that the ISP router will be the DR, we’ll give it the highest possible OSPF priority (note

that this is configured under the appropriate interface):


ISP(config)# interface fastethernet 0/0

ISP(config-if)# ip ospf priority 255

ISP(config-if)# end

ISP#

Next, to ensure that the Remote2 router never participates in the election process we can set its

OSPF priority to zero:

Remote2# configure terminal

Remote2(config)# interface fastethernet 0/0

Remote2(config-if)# ip ospf priority 0

Remote2(config-if)# end

Remote2#

With our current configuration, the Remote1 router will always end up as the BDR. What if, however,

we later added another router to the network. Because it would, by default, also have an OSPF

priority of 1, it is possible that it could take over the role of BDR.

Za svaki slučaj da mu bude osigurano mesto BDR-a:

Remote1# configure terminal

Remote1(config)# interface fastethernet 0/0

Remote1(config-if)# ip ospf priority 254

Remote1(config-if)# end

Remote1#

R1(config)#interface fastEthernet0/0

R1(config-if)#ip ospf priority 255

R1(config-if)#end

Primer:






ISP#

-----------------------------------------------------------------------------------------

4. Autentifikacija OSPF:

****************************


ISP(config)# interface fastethernet 0/0

ISP(config-if)# ip ospf message-digest-key 1 md5 xooph8MuBaeph5ee

ISP(config-if)# router ospf 1

ISP(config-router)# area 0 authentication message-digest


ISP#

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------

Show naredbe kod OSPF-a

**************************************

Powerful OSPF troubleshooting commands include:

- show ip protocols

- show ip ospf

- show ip ospf interface

- show ip route

#show ip ospf neighbor

***********************************

When troubleshooting OSPF networks, the show ip ospf neighbor command can be used to verify

that the router has formed an adjacency with its neighboring routers. If the router ID of the

neighboring router is not displayed, or if it does not show as a state of FULL, the two routers have not

formed an OSPF adjacency.

Postupno šta šta znači kod naredbe:

- Neighbor ID - The router ID of the neighboring router.

- Pri - The OSPF priority of the interface.

- State - The OSPF state of the interface. FULL state means that the router and its neighbor have

identical OSPF link-state databases.

- Dead Time - The amount of time remaining that the router will wait to receive an OSPF Hello packet

from the neighbor before declaring the neighbor down. This value is reset when the interface

receives a Hello packet.

- Address - The IP address of the neighbor's interface to which this router is directly connected.

- Interface - The interface on which this router has formed adjacency with the neighbor.

Two routers may not form an OSPF adjacency if:

- The subnet masks do not match, causing the routers to be on separate networks.

- OSPF Hello or Dead Timers do not match.

- OSPF Network Types do not match.

- There is a missing or incorrect OSPF network command.

#show ip ospf or #show ip ospf interface

*****************************************************

One command you can use to verify the current router ID is show ip protocols. Some IOS versions do

not display the router ID as shown in the figure. In those cases, use the show ip ospf or show ip ospf

interface commands to verify the router ID.

Primer: Router#show ip ospf interface serial0/0/1

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

***********************************************

6. BGP

-

-

**************************************************

Border Gateway Protocol (BGP) is an inter-autonomous routing protocol - the routing protocol of the

Internet.

BGP is the only routing protocol that uses an actual autonomous system number in its configuration.

*************************************************

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

***************************************

7. IS IS

- Link State Routing Protocol

****************************************

IS-IS was originally designed for the OSI protocol suite and not the TCP/IP protocol suite. Later,

Integrated IS-IS, or Dual IS-IS, included support for IP networks. Although IS-IS has been known as the

routing protocol used mainly by ISPs and carriers, more enterprise networks are beginning to use IS-

IS.

OSPF and IS-IS share many similarities and also have many differences. There are many pro-OSPF and

pro-IS-IS factions who discuss and debate the advantages of one routing protocol over the other.

Both routing protocols provide the necessary routing functionality needed.

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

-- stavljanje svuda banera, opisa -- MOTD - Message of the Day

RouterA(config-if)#description This link is connected to the Accounting Lan

RouterA(config)#access-list 101 remark This list stops the telnet to the Marketing net

RouterA(config)#banner motd #This router is connected to the marketing and accounting LANS#

--------------------------------------------------------------------------------------------------------------

- SKRAĆENICE

-- hotkeys --

Control P Recalls the previous command in the history buffer

Control N Recalls the next command in the history buffer

Control E Goes to the end of the line

Control A Goes to the beginning of the line

--------------------------------------------------------------------------------------------------------------

-- isključivanje kontaktiranaj DNS-a na pogresne komande -- disable DNS

RouterA(config)#line con 0

RouterA(config-line)#transport preferred none

Objašnjenej naširoko:

--Stop the router from looking-up DNS server for wrong commands.--

When you misspell a command and hit the ‘Enter’ key, the router does not recognize the command

and thinks that it might be a host name. The router, then, tries to contact the DNS server to resolve

the name to an IP address so it would telnet it. This would take a large amount of time, especially

when you have not setup a valid DNS server (because the router will broadcast the request and waits

for a DNS server to reply). To turn this off, use the ‘transport preferred none’ command in the

console and vty lines.

kada NIJE uključen:

MyRouter#shwo

Translating "shwo"...domain server (10.1.1.2)

% Unknown command or computer name, or unable to find computer address

MyRouter#

ISKLJUČIVANJE:

! Console port

line con 0

transport preferred none

! VTY Ports

line vty 0 5

transport preferred none

kada je UKLJUČEN:

MyRouter#shwo

^

% Invalid input detected at '^' marker.

--------------------------------------------------------------------------------------------------------------

-- Setup the Bandwidth of serial interfaces -- podesavanje bandwidth-a na seriskim/seriskom

interfejsu

Use the ‘bandwidth’ command for setting the bandwidth of ALL serial interfaces to guarantee the

correct calculation of routing table. The bandwidth of a serial link is dependant on the type of WAN

connection you are using

Primer 1:

RouterA(config)#int serial 0

RouterA(config-if)#bandwidth 1024 >> This means the link bandwidth is 1Mbit/second

Primer 2:

interface serial0

description This is a 56k link

bandwidth 56

--------------------------------------------------------------------------------------------------------------

-- 6. Turn off Auto-summarization of routing updates when using subnetted addresses. -- iskljucivanje

automacke sumarizacije

If you are using subnetting, remember use the ‘no auto-summary’ command to turn off auto-

summarization. This is when using routing protocols that support it, like OSPF.

Example:

RouterA(config)#no auto-summary

--------------------------------------------------------------------------------------------------------------

-- 9. Keep the IP addresses of servers and printers out of the DHCP pool. -- iskljuicavanje DHCP-a za

servere i stampace

When using the router as a DHCP server, do NOT forget to exclude the addresses of server and

printers off the DHCP pool.

Example:

RouterA(config)#ip dhcp excluded-address 192.168.0.1

RouterA(config)#ip dhcp excluded-address 192.168.0.1 192.168.0.10

You can use a single IP address in this command or a start-IP and end-IP to define a range.

--------------------------------------------------------------------------------------------------------------

-- Keep a scheduled ‘reload’ when configuring a router remotely. -- komanda reload za restartovanej

rutera i to posle odredjenog vremena po gubitku veze

When you are configuring a router remotely, you might do something wring and loose the

connectivity with the router. In this case, you will need to restart the router physically. There are

chances that no one is around the router to restart it for you. You can solve this by yourself by using

the ‘reload in xx’ command. This command schedules a reload after xx minutes. So, before you start

nosing around the router remotely, issue this command and schedule a reload. If something goes

wrong and you loose the connectivity with the router, the router will reload and you get back in

business. And if things go smooth and you don’t need to reload after all, you can issue a ‘reload

cancel’ command to stop the scheduled restart from happening.

Primer:

-- palim reload --

MyRouter#reload in 3

Reload scheduled in 3 minutes

Proceed with reload? [confirm]y

-- gasim reload --

MyRouter#reload cancel

--------------------------------------------------------------------------------------------------------------

-- A common frame-relay misunderstanding.--

The encapsulation type on the physical interface must be set to frame-relay before any sub-

interfaces can be created. The default encapsulation type is usually HDLC (High-level Data Link

Control).

So, before starting to create our frame-relay sub-interfaces, we need to first set the encapsulation

type to frame-relay on the physical interface:

interface serial0

encapsulation frame-relay

-- Now we can create our sub-interfaces:

interface serial0.1 point-to-point

description This is our first sub interface for serial1

--------------------------------------------------------------------------------------------------------

--- Provere: ---- show naredbe

********************

1. R2#show ip interface brief - Check the status of the interfaces on each router

2. R3#show running-config - provera tekuće konfiguracije koja je u RAM-u

3. R3#show ip route - To display the current state of the routing table, use the show ip route

command in EXEC mode.

ili napisati šta sve izbacuje:

show ip route [[ip-address [mask] [longer-prefixes]] | [protocol [process-id]] | [list access-list-number

| access-list-name]]

4. traceroute - is a computer network diagnostic tool for displaying the route (path) and measuring

transit delays of packets across an Internet Protocol (IP) network

-- Sumirano SHOW komande --

show version – Shows some good information like the IOS version, the configuration-register value

and the interfaces available.

show ip route – Shows the routing table

show ip interface – Shows the access-lists applied to interfaces

show access-list – Shows the contents of access-lists

show ip protocols – Shows information about the routing protocols currently running.

show cdp neighbor detail – Shows detailed information about neighboring devices.

show interface – Show status information about interfaces.

show run – Shows the running configuration, i.e., all the commands now in action.

show ip arp - Displays the entire ARP (Address Resolution Protocol)table, which is the MAC-to-IP

resolution table.

show version - This command gives a good amount of information; the IOS version you are running,

the available interfaces, the system uptime, the last reload reason, and the configuration register

setting.

show ip protocols - Displays information about the currently running routing protocols.

show ip route - The old standby, which displays the entire IP route table.

show ip route summary - Gives a very useful summary of the IP route table.

show ip interface - Gives a summary of each interface from the IP level.

show ip interface brief - A very brief summary of each interface.

show ip traffic - An extensive summary of IP traffic statistics on the router.

show access-list - This useful command not only shows the all the currently configured access-lists,

but it also shows you the number of hits each line has received. You can use this information to

better troubleshoot your access-lists.

show cdp neighbors - Assuming you have CDP enabled, this command gives you a report of all Cisco

devices that the current device is connected to. CDP stands for Cisco Discovery Protocol, which can

be an invaluable tool.

show cdp neighbors detail - This command gives even more information about CDP neighbors.

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

***********************

---- SWITCH ------ kofiguracija/podesavanje switcha-a

***********************

Kresnemo switch

Switch> en

Switch# config t

Switch(config)#

Set the device hostname to Switch1.

Switch(config)# hostname Switch1

Switch1(config)#

Configure the MOTD banner.

Switch1(config)# banner motd % Ovo je ovde opis switcha %

Step 4: Configure the privileged exec password.

Set the privileged exec password to cisco.

Switch1(config)# enable secret cisco

Step 5: Configure the console password.

Set the console access password to class.

Switch1(config)# line console 0

Switch1(config-line)# password class

Switch1(config-line)# login

Step 6: Configure the virtual line password.

Set the virtual line access password to class. There are 16 virtual lines that can be configured on a

Cisco IOS switch, 0 through 15.

Switch1(config-line)# line vty 0 15

Switch1(config-line)# password class

Switch1(config-line)# login

Apply the descriptions on the switch interface with the interface configuration command,

description:

Switch1(config)# interface fa0/1

Switch1(config-if)# description Connection to Router1


Switch1(config-if)# description Connection to host computer 2


Switch1(config-if)# description Connection to host computer 3

Switch1(config-if)# end

Switch1#

Step 8: Save RAM configuration to NVRAM.

For a configuration to be used the next time the switch is powered on or reloaded, it must be

manually

saved in NVRAM. Save the RAM configuration to NVRAM:

Switch1# copy run start

Destination filename [startup-config]? <ENTER>

Building configuration...

[OK]

Switch1#

Podesavanje sata

Cisco# clock set 19:50:00 25 June 2007

Precice/skracenice:

Tab - Completes the remainder of the command or keyword

Ctrl-R - Redisplays a line

Ctrl-Z - Exits configuration mode and returns to the EXEC

Down Arrow - Allows user to scroll forward through former commands

Up Arrow - Allows user to scroll backward through former commands

Ctrl-Shift-6 - Allows the user to interrupt an IOS process such as ping or traceroute

Ctrl-C - Aborts the current command and exits the configuration mode

Pregled sta ima na uredjaju - show naredbom

show startup-config, show running-config, and show interfaces.

show version

C:\host1>arp -a ili arp -d

show mac-address-table

Brisanje Sadrzaja NVRAM:

Erase the NVRAM configuration file:

Router1# erase start

Erasing the nvram filesystem will remove all configuration files! Continue?

[confirm] <ENTER>

[OK]

Erase of nvram: complete

Reload the router:

Router1# reload

Proceed with reload? [confirm] <ENTER>

When the router reboots, enter the global configuration mode:

Router> en

Router# config t

Router(config)#

Before turning off power to the router and switch, remove the NVRAM configuration file from each

device with the privileged exec command erase startup-config.

Konfiguracioni modovi

Router#configure terminal

Router(config)#

Specific Configuration Modes

Interface mode - to configure one of the network interfaces (Fa0/0, S0/0/0,..)

Line mode - to configure one of the lines (physical or virtual) (console, AUX, VTY,..)

Router mode - to configure the parameters for one of the routing protocols.

--------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

Switch#configure terminal

Switch(config)#interface Fastethernet 0/1

Switch(config-if)#description Ovo je sad neki opis

Switch(config-if)#exit

Switch(config)#hostname Davitko

Davitko(config)#exit

Davitko#

ili

Switch#configure terminal

Switch(config)#interface vlan 1

Switch(config-if)#description Ovo je sad neki opis

Switch(config-if)#ip address 192.168.1.2 255.255.255.0

Switch(config-if)#no shutdown

Switch(config-if)#exit

Switch(config)#ip default-gateway 192.168.1.1

Switch(config)#exit

Switch#

--------------------------------------------------------------------------------------------------------------------------------------

------------

Legenda:

user mode: Router>; Switch>

privileged mode: Router#; Switch#

Global Configuration mod: Router(config)#; Switch(config)#

Other Configuration Mode: Router(config-mode)#; Switch(config-mode)#

--------------------------------------------------------------------------------------------------------------------------------------

------------

-------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------------------

************

Teorija:

*************

1. TCP i UDP port

TCP и UDP порт (енгл. TCP and UDP port) је софтверски задат канал којим комуницирају

апликације путем рачунарских мрежа. Овај канал на једној од страна комуникације

представљен је јединственим бројем који користе протоколи транспортног слоја ОСИ модел у

циљу разликовања (раздвајања), идентификације и праћења комуникације апликација.

Протоколи TCP и UDP наводе бројеве потова у својим заглављима као изворишни и одредишни

порт. При клијент/сервер комуникацији изворишни порт представља број порта који означава

апликацију која иницира комуникацију, док одредишни порт означава статички број порта

сервиса на серверу. Клијенти динамички бирају број порта за сваку конверзацију.

-------------------------------------------------------------------------------------------------------------

2. DNS

DNS (енгл. Domain name system) је, у основи, систем који претвара имена рачунара (hostnames)

у ИП адресе. DNS такође обезбеђује податке и о серверима електронске поште на домену (MX),

почетном DNS серверу (SOA) и друге. DNS је заснован на хијерархијском принципу и једна је од

основних компоненти интернета.

Када у свој браузер укуцате веб адресу http://sr.wikipedia.org/ , ваш рачунар ће уз помоћ DNS

сервера то име претворити у адресу 208.80.152.2, што је ИП адреса рачунара на којем се налази

тај сајт.

Најважнији типови података који се чувају у DNS--у јесу следећи:

тип А — адреса - повезује име рачунара и његову адресу

тип CNAME — канонско име (енгл. Cannonical NAME) - повезује једно име рачунара (канонско

име) са другим именом

тип MX — размена поште (енгл. Mail eXchange) - адреса сервера задуженог за електронску

пошту

тип SOA — почетни ауторитет (енгл. Start Of Authority) - адреса DNS сервера који је надлежан за

домен

Постоје још и PTR, NS, AAAA, SRV, TXT, NAPTR, LOC и други мање значајни типови података.

-------------------------------------------------------------------------------------------------------------

3. DHCP

DHCP (енгл. Dynamic Host Configuration Protocol или протокол за динамичко конфигурисање

рачунара) је скуп правила који омогућава уређајима на рачунарској мрежи да траже и добију

ИП адресу од DHCP сервера, дакле да прибави аутоматски дељену адресу и сазна додатне

информације као што је адреса његовог рутера за први скок и адреса његовог ДНС сервера.

DHCP је у стању да аутоматизује мрежне аспекте, отуда је и назван plug-and-play протоколом.

-- Опис рада --

DHCP је протокол између клијента и сервера. Клијент је обично рачунар који се прикључује на

мрежу и жели да добије информације о конфигурацији мреже и своју ИП адресу.

DHCP сервер је углавном инсталиран на засебном серверу на рачунарској мрежи, мада може

бити покренут и на рутеру, који клијентима додељује адресе из унапред одређеног скупа ИП

адреса. Клијентски уређаји могу бити рачунари, мрежни штампачи и мрежни адаптери. Уз ИП

адресу клијенти могу добити и остала мрежна подешавања као што су подразумевани излаз са

мреже (default gateway), мрежна маска, адреса DNS сервера и други. У супротном, да нема

DHCP сервера на мрежи, све ове вредности би морале да се уносе ручно. DHCP се стара да све

ИП адресе буду јединствене, тј. да нема две исте ИП адресе у мрежи.

Комуникација сервера и клијента [уреди]

Шема DHCP сесије

Откривање - Клијентски рачунар (или било који други уређај), уколико нема подешавања за

приступ рачунарској мрежи, прво ће пробати да нађе DHCP сервер на мрежи, преко DHCP

discovery ( DHCP откривање) пакета који се шаље бродкастом.

Понуда - Када DHCP сервер прими DHCP discovery пакет, он на њега реагује одговором који се

назива DHCP offer ( DHCP понуда). Сервер у том тренутку резервише једну ИП адресу за

клијента.

Захтев - Клијент који прими DHCP понуду, новим бродкастом обавештава сервер који му је

послао понуду, али и остале DHCP сервере на мрежи, да је добио ту понуду. Клијент шаље

DHCP request (захтев за доделу ИП адресе) и у том захтеву наводи од ког сервера то захтева.

Остали сервери могу да скину разервацију са ИП адресе коју су му понудили.

Потврда - Сервер новим пакетом DHCP acknowledgement шаље клијенту саме потребне мрежне

податке. Тиме се завршава процес.

У неким случајевима, клијент може захтевати своју последњу додељену ИП адресу. Уколико му

DHCP сервер одобри тај захтев, он може имати исту адресу и након поновног укључивања (или

поновног прикључивања у мрежу). У пракси је ово врло чест случај, тако да рачунар може дуго

времена имати исту ИП адресу на мрежи, иако на њој постоји DHCP сервер.

Уколико клијент захтева ИП адресу, а на мрежи не постоји DHCP сервер, или му ниједан DHCP

сервер не може издати адресу, клијент добија адресу из опсега приватних ИП адреса,

поступком који се зове аутоконфигурисање.

Динамичка и статичка ИП адреса [уреди]

-------------------------------------------------------------------------------------------------------------

4. IP adresa

ИП адреса коју сервер додели клијенту се назива динамичка ИП адреса. Термин супротан

овоме је статичка ИП адреса, коју карактерише да је ИП адреса клијента унапред одређена и

већ уписана у рачунар. Microsoft Windows XP користи израз Obtain an IP address automatically за

динамичку адресу, а Use the following IP address за подешавање статичке ИП адресе.

Термини динамичка и статичка ИП адреса нису у вези са терминима статичка и јавна ИП

адреса. У приватним мрежама постоје и статичке и динамичке адресе. Јавне адресе су

углавном статичке, али поједини провајдери интернета могу својим клијентима динамички

додељивати јавне ИП адресе.

-------------------------------------------------------------------------------------------------------------

5.ICMP

ICMP (енгл. Internet Control Messageing Protocol) је протокол слоја мреже који обезбеђује

поједине механизме оглашавања. У суштини, ICMP обезбеђује повратну спрегу у вези

проблема у комуникацији у окружењу. Примери употребе ICMP-а су када пакет не може да

стигне до одредишта, рутер нема довољну величину бафера да би га проследио (корисник да

би га примио) или када рутер може да упути поруку да постоји краћа рута. У већини случајева,

ICMP порука се шаље као одговор на пакет, било да га шаље рутер који се налази на путу

датаграма или хост који је одредиште.

Иако је ICMP на истом слоју као и IP у TCP/IP архитектури, он је у ствари корисник IP-a. ICMP

порука се прво направи па се онда предаје IP-у који спаја поруку са IP заглављем и онда

преноси резултујући пакет на већ уобичајени начин. Из разлога што се ICMP поруке шаљу као IP

пакети, њихова испорука није гарантована нити је њихово коришћење поуздано.

ICMP порука оглашавања може бити послата у неком од следећих случајева:

1. Конфирмација (потврда) корисника - Обезбеђују механизам за тестирање да ли је могућа

комуникација између два ентитета. Овај механизам најчешће користи PING апликација. -

pingovanje

2. Недоступност дестинације или сервиса -

Кодови које користи порука у овом случају:

0 за недоступну мрежу (net unreachable)

1 за недоступног корисника (host unreachable)

2 за недоступан протокол (protocol unreachable)

3 за недоступан порт (port unreachable)

Рутер може да врати ову поруку ако не зна како да дође до одредишне мреже. У неким

мрежама рутер може да процени да је неки хост недоступан и онда врати поруку о томе.

Одредишни хост такође може да врати ову поруку ако је кориснички протокол или нека од

приступних тачака сервиса виших слојева недоступана.

3. Обавештење о истеку живота поруке - Рутер ће вратити поруку о истеку времена ако животни

век датаграма истекне

4. Промена руте (маршуте) - Рутер шаље поруку редирекције хосту који је прикачен на

директно повезан рутер да би обавестио хост о бољој рути ка одређемом одредишту.

5. Порука о стишавању протока из изворишта - Рутери или одредиште шаљу ову поруку

изворишном хосту, тражећи да смањи брзину слања пакета према одредишту. Када се прими

порука о стишавању протока, изворишни хост би требало да смањи брзину којом шаље пакете

ка одређеној дестинацији док не престане да добија поруке о стишавању протока. Ова порука

може бити коришћена од стане рутера или хоста који мора да одбаци пакете због пуног

бафера. У том случају ће рутер или хост објављивати поруку о смањењу протока за сваки

датаграм који је одбачен. Систем ће упозорити да је дошло до нагомилавања овом поруком

када се бафер приближи горњој граници капацитета.

6. Порука са ознаком времена и порука са одговором са ознаком времена - Пошиљалац поруке

са ознаком времена може да укључи и идентификатор и низ бројева у параметарским пољима

и укључи време слања поруке (почетак ознаке времена). Прималац бележи време када је

примио поруку и време када је послао поруку са одговором са ознаком времена. Ако је порука

са ознаком времена послата коришћењем стриктног изворишног рутирања, онда могу бити

мерене и карактеристике кашњења одређене руте.

7. Поруке са захтевом адресне маске и поруке са одговором са адресном маском - Корисне су у

окружењу са подмрежама. Поруке са захтевом адресне маске и поруке са одговором

омогућавају хосту да научи адресну маску за LAN за који је везан. Хост шаље broadcast са

поруком са захтевом адресне маске на LAN.

-----------------------------------------------------------------------------------------------------------

Nastavak...

*****************************************************

-------------- Pojmovi - Termini -----------

*****************************************************

---------- Protokoli --------

1. IP (интернет протокол) (енгл. Internet Protocol) је протокол трећег слоја ОСИ референтног

модела (слоја мреже). Садржи информације о адресирању, чиме се постиже да сваки мрежни

уређај (рачунар, сервер, радна станица, интерфејс рутера) који је повезан на интернет има

јединствену адресу и може се лако идентификовати у целој интернет мрежи, а исто тако

садржи контролне информације које омогућују пакетима да буду прослеђени (рутирани) на

основу познатих IP адреса.

-------------------------------------------------------------------------------------------------------------

2. ------------ Statička IP -----------------

Statičke IP adrese su fiksne adrese koje se menjaju samo ukoliko im to ručno naredi. One se koriste u

slučajevima kada administrator ne želi da menja IP informaciju, a takvi slučajevi su interni serveri na

LAN mreži, bilo koji server koji je povezan na Internet, i mrežni ruteri. Sa statičkim IP adresiranjem vi

dodeljujete adresu i ostavljate je takvom. Druge mašine znaju da ste uvek na toj određenoj IP adresi i

mogu vas kontaktirati uvek preko te adrese.

-------------------------------------------------------------------------------------------------------------

3. ----------------- DHCP --------------------

DHCP (akronim od Dynamic Host Configuration Protocol), je način na koji IP adresa može biti

određena računaru prilikom startovanja. Kada se pokrene DHCP klijent, on onda šalje zahtev na

lokalnu mrežu koji je namenjen DHCP serveru da mu dodeli IP adresu. DHCP server ima skup (ili

opseg) IP adresa koje su dostupne. Server će odgovoriti na ovaj zahtev sa IP adresom iz skupa,

zajedno sa vremenom izdavanja (lease time). Jednom kada vreme izdavanja za datu IP adresu

istekne, klijent mora opet da kontaktira server i da ponovi pregovor.

Klijent će prihvatiti IP adresu od servera i podesiće zahtevani interfejs sa tom IP adresom. Međutim,

postoji jedan zgodan trik kojeg DHCP klijenti koriste prilikom pregovora za IP adresu koja će im biti

dodeljena. Klijent će zapamtiti poslednju dodeljenu IP adresu, i tražiće da mu server opet dodeli

poslednju dodeljivanu IP adresu opet prilikom pregovora. Ako je moguće, server će to uraditi, ali ako

nije, dodeljuje se nova adresa. Pa tako, pregovor liči na sledeći razgovor:

Klijent: Ima li DHCP server dostupan na mreži?

Server: Da, ima. Ovde sam.

Klijent: Meni treba IP adresa.

Server: Možeš uzeti 192.168.10.10 na 19200 sekundi.

Klijent: Hvala.

Klijent: Ima li DHCP server dostupan na mreži?

Server: Da, ima. Ovde sam.

Klijent: Meni treba IP adresa. Poslednji put kad smo

razgovarali, dobio sam 192.168.10.10;

Mogu li je dobiti opet?

Server: Da, možeš (ili Ne, ne možeš: uzmi 192.168.10.12 umesto te).

Klijent: Hvala.

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4. --- Ruter ---

The very first router, used for the Advanced Research Projects Agency Network (ARPANET)

The router in the figure has four interfaces. Each interface has a Layer 3 IP address and subnet mask

that configures it for a different network. The Ethernet interfaces also have Layer 2 Ethernet MAC

addresses.

The WAN interfaces are using different Layer 2 encapsulations. Serial 0/0/0 is using HDLC and Serial

0/0/1 is using PPP. Both of these serial point-to-point protocols use a broadcast address for the Layer

2 destination address when encapsulating the IP packet into a data link frame.

Tri principa kako ruter donosi odluku šta raditi sa pritiglim paketom:

1. Every router makes its decision alone, based on the information it has in its own routing table.

2. The fact that one router has certain information in its routing table does not mean that other

routers have the same information.

3. Routing information about a path from one network to another does not provide routing

information about the reverse, or return, path.

Alex Zinin

-------------------------------------------------------------------------------------------------------------

5. ---- Ruting Protokoli --- Protokoli u rutiranju

Протокол рутирања (енгл. Routing protocol) представља сет правила којим рутери динамички

размењују информације о путањама (рутама) којима пакет треба да се креће да би досегао

жељену дестинацију.

5.1 Карактеристике протокола рутирања[уреди]

--- Време конвергенције - за мрежу кажемо да је конвергентна када су табеле рутирања код

свих рутера унутар мреже, комплетне и исправне. Време конвергенције је сходно томе, време

за које мрежа исконвергира након извршене промене у топологији (сразмерно је величини

мреже).

У време конвергенције је укључено:

-Размена информација

-Обрада информација, процена најбољих рута

-Уношење измена у табеле рутирања

--- Скалабилност - дефинише колика мрежа може да буде, у зависности од протокола који се

користи.

--- Класност - протоколи рутирања могу да буду класни и безкласни.

- Класни су старији протоколи (RIPv1 и IGRP) који подразумевају да адреса припада некој од

класа (А, Б, Ц).

- Безкласни, при размени информација укључују подмрежну маску уз адресу мреже.

--- Заузетост ресурса - протоколи рутирања при размени и обради информација заузимају

хардверске ресурсе (меморију, процесорско време или пропусни опсег линка).

--- Имплементација и одржавање - дефинише ниво знања који је потребно да има

администратор мреже, како би применио и одржавао мрежу која ради са одређеним

протоколима рутирања.

5.2 Класификација протокола рутирања

.

a) На основу области рутирања, унутар аутономног система или између аутономних система.

a.1) Интерни протоколи рутирања (енгл. Interior Getaway Routing Protocols)

- Протоколи рутирања на основу вектора удаљености (енгл. Distance Vector Routing

Protocols)

- Протоколи рутирања на основу стања линка (енгл. Link-State Routing Protocols)

a.2) Екстерни протоколи рутирања (енгл. Exterior Getaway Routing Protocols)

- Протоколи рутирања на основу вектора путање (енгл. Path Vector Routing Protocols)

На основу верзије интернет протокола чије пакете прослеђују

IPv4 протоколи рутирања

Класни протоколи рутирања (енгл. Classfull Routing Protocols)

Безкласни протоколи рутирања (енгл. Classless Routing Protocols)

IPv6 протоколи рутирања

IPX протоколи рутирања

Apple Talk протоколи рутирања

На јавне протоколе и протоколе развијене од стране појединих фирми који су у њиховом

власништву.

Табела протокола рутирања[уреди]

Табела протокола рутирања формирана на основу класификације

Интерни Екстерни

На основу вектора удаљености На основу стања линка Path Vector

IPv4, класни RIP IGRP EGP

IPv4, безкласни RIPv2 EIGRP OSPFv2 IS-IS BGP

IPv6 RIPng EIGRP за IPv6 OSPFv3 IS-IS за IPv6 BGPv4 за IPv6

5.3 Интерни протоколи рутирања

a) Вектор удаљености

Протоколи рутирања на основу вектора удаљености (енгл. Distance Vector Routing Protocols)

укључују протоколе као што су: RIP, IGRP и EIGRP. Протоколи RIP и IGRP функционишу по

принципу Белман-Форд алгоритма (енгл. Bellman-Ford Algorithm), док је EIGRP напреднији по

том питању и користи (DUAL) (енгл. Diffusing Update Algorithm). Као што и само име говори,

рутери размењују информације којима сазнају удаљеност (дистанцу) и правац (интерфејс или

рутер) ка некој од удаљених мрежа, при чему немају информацију о самом путу до одредишне

мреже. Размењивање информација се врши тако што сваки од рутера периодично прослеђује

целу табелу рутирања суседним рутерима.

b) Стање линка

Рад протокола рутирања на основу стања линка (енгл. Link-State Routing Protocols) се заснива на

Дајкстрином (SPF) алгоритму, познати су још као (SPF) протоколи (енгл. Shortest Path First)

најпре најкраћа путања. Како су ови протоколи интерни протоколи рутирања, они одређују

најкраће путање унутар истог аутономног система, који се у зависности од величине и

сложености може даље хијерархијски поделити на зоне.

При достизању конвергенције рутери који припадају истој зони извршавају следеће процесе:

- Сваки рутер испитује своје везе ка суседним рутерима или мрежама.

- Размењујући Hello пакете открива суседе, успоставља и одржава суседске везе.

- Сваки рутер формира LSP (енгл. Link-State Packet) који садржи информације о стању сваке

директно конектоване везе.

- Сваки рутер прослеђује LSP ка суседима који на основу њих формирају своје базе података.

(Суседи даље прослеђују својим суседима LSP, све док сви рутери унутар зоне не приме пакете

од сваког рутера)

- Користећи базе података, рутери формирају топологију мреже.

Потом ка свакој од мрежа одређују најкраће путање које уносе у табеле рутирања (мрежа је

исконвергирана).

Овој групи протокола припадају:

OSPF, (енгл. Open Shortest Path First)

DNA Phase V протокол за DEC мрежна окружења, претеча IS-IS протокола.

IS-IS, (енгл. Intermediate System to Intermediate System)

NLSP Novellova мрежна окружења, (енгл. NetWare Link Services Protocol)

AURP, (енгл. AppleTalk Update Routing Protocol) из AppleTalk скупа протокола.

5.4 Листа протокола рутирања[уреди]

RIP, (енгл. Routing Information Protocol)

RIPv2, (енгл. Routing Information Protocol) верзија 2

RIPng, (енгл. Routing Information Protocol Next Generation) верзија за IPv6

Cisco протоколи рутирања:

IGRP, (енгл. Interior Gateway Routing Protocol)

EIGRP, (енгл. Enhanced Interior Gateway Routing Protocol)

OSPF, (енгл. Open Shortest Path First)

IS-IS, (енгл. Intermediate System to Intermediate System)

EGP, (енгл. Exterior Gateway Protocol)

BGP, (енгл. Border Gateway Protocol)

CSPF, (енгл. Constrained Shortest Path First)

-------------------------------------------------------------------------------------------------------------

6. RIP

RIP је интерни протокол рутирања (енгл. Interior Getaway Routing Protocols). Користећи Белман-

Фордов алгоритам (енгл. Bellman-Ford Algorithm) динамички ажурира табеле рутирања рутера

унутар истог аутономног система. Као метрику узима скок (енгл. hop) то јест удаљеност од

мреже, што га сврстава у групу протокола рутирања на основу вектора удаљености (енгл.

Distance Vector Routing Protocols).

------ Dinstance Vektor i Link State, šta ne valja:

Distance vector and link state routing are both intra-domain routing protocols. They are used inside

an autonomous system, but not between autonomous systems. Both of these routing protocols

become intractable in large networks and cannot be used in Inter-domain routing. Distance vector

routing is subject to instability if there are more than a few hops in the domain. Link state routing

needs huge amount of resources to calculate routing tables. It also creates heavy traffic due to

flooding.

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7. Ruting šeme

Routing schemes differ in their delivery semantics:

1) unicast delivers a message to a single specific node

2) broadcast delivers a message to all nodes in the network

3) multicast delivers a message to a group of nodes that have expressed interest in receiving the

message

4) anycast delivers a message to anyone out of a group of nodes, typically the one nearest to the

source

5) geocast delivers a message to a geographic area

Unicast is the dominant form of message delivery on the Internet. This article focuses on unicast

routing algorithms.

The Internet Protocol and other network addressing systems recognize three main addressing

methodologies;

Unicast addressing uses a one-to-one association between destination address and network

endpoint: each destination address uniquely identifies a single receiver endpoint.

Broadcast or multicast addressing uses a one-to-many association, datagrams are routed from a

single sender to multiple endpoints simultaneously in a single transmission. The network

automatically replicates datagrams as needed for all network segments (links) that contain an eligible

receiver.

Anycast addressing routes datagrams to a single member of a group of potential receivers that are all

identified by the same destination address. This is a one-to-one-of-many association.

*** 1.Unicast ****

In computer networking, unicast transmission is the sending of messages to a single network

destination identified by a unique address.

The term unicast is contrasted with the term broadcast which means transmitting the same data to

all possible destinations. Another multi-destination distribution method, multicasting, sends data

only to interested destinations by using special address assignments.

Unicast messaging is used for all network processes in which a private or unique resource is

requested.

Internet radio stations using unicast connections may have high bandwidth costs.

These terms are also used by streaming content providers' services. Unicast-based media servers

open and provide a stream for each unique user. Multicast-based servers can support a larger

audience by serving content simultaneously to multiple users.

*** 2. Broadcasting *************

In telecommunication and information theory, broadcasting refers to a method of transferring a

message to all recipients simultaneously. Broadcasting can be performed as a high level operation in

a program, for example broadcasting Message Passing Interface, or it may be a low level networking

operation, for example broadcasting on Ethernet.

In computer networking, broadcasting refers to transmitting a packet that will be received by every

device on the network.[1] In practice, the scope of the broadcast is limited to a broadcast domain.

Broadcast a message is in contrast to unicast addressing in which a host sends datagrams to another

single host identified by a unique IP address.

Broadcasting is largely confined to local area network (LAN) technologies, most notably Ethernet and

token ring, where the performance impact of broadcasting is not as large as it would be in a wide

area network.

The successor to Internet Protocol Version 4 (IPv4), IPv6 also does not implement the broadcast

method, so as to prevent disturbing all nodes in a network when only a few may be interested in a

particular service.

BROADCAST Domain

*****************************

A broadcast domain is a logical division of a computer network, in which all nodes can reach each

other by broadcast at the data link layer. A broadcast domain can be within the same LAN segment

or it can be bridged to other LAN segments.

In terms of current popular technologies: Any computer connected to the same Ethernet repeater or

switch is a member of the same broadcast domain. Further, any computer connected to the same set

of inter-connected switches/repeaters is a member of the same broadcast domain. Routers and

other higher-layer devices form boundaries between broadcast domains.

This is as compared to a collision domain, which would be all nodes on the same set of inter-

connected repeaters, divided by switches and learning bridges. Collision domains are generally

smaller than, and contained within, broadcast domains.

While some layer two network devices are able to divide the collision domains, broadcast domains

are only divided by layer 3 network devices such as routers or layer 3 switches. Separating VLANs

divides broadcast domains as well, but provides no means to network these without layer 3

functionality.

Collision domain

**********************

A collision domain is a section of a network where data packets can collide with one another when

being sent on a shared medium or through repeaters, in particular, when using early versions of

Ethernet. A network collision occurs when more than one device attempts to send a packet on a

network segment at the same time. Collisions are resolved using carrier sense multiple access with

collision detection (CSMA-CD) in which the competing packets are discarded and re-sent one at a

time. This becomes a source of inefficiency in the network.[1]

Only one device in the collision domain may transmit at any one time, and the other devices in the

domain listen to the network in order to avoid data collisions. Because only one device may be

transmitting at any one time, total network bandwidth is shared among all devices. Collisions also

decrease network efficiency on a collision domain; if two devices transmit simultaneously, a collision

occurs, and both devices must retransmit at a later time.

Collision domains are found in a hub environment where each host segment connects to a hub that

represents only one collision domain and only one broadcast domain. Collision domains are also

found in wireless networks such as Wi-Fi.

Modern wired networks use a network switch to eliminate collisions. By connecting each device

directly to a port on the switch, either each port on a switch becomes its own collision domain (in the

case of half duplex links) or the possibility of collisions is eliminated entirely in the case of full duplex

links.

--- Znači Vladimir Ćirić je reko: ---

Kolizioni domen - je na lejeru 1. Na primer svi računari povezani na hub ili na koaksijalni, onaj stari

bus, su na kolizionom domenu. To je grupa kablova gde se "čuje" kolizija koja se desila na tom

domenu. Na sviču postoji mikrosegmentacija, jer kolizioni domen čini samo dva uređaja: računar i

port sviča.

Brotkast domen je na lejeru 2 ili 3.

Svič deli kolizioni domen, ali ne i brotkast. Ruter deli i kolizioni i brotkast domen.

**** 3. Multicast *****

In computer networking, multicast is the delivery of a message or information to a group of

destination computers simultaneously in a single transmission from the source. Copies are

automatically created in other network elements, such as routers, but only when the topology of the

network requires it.

Multicast is most commonly implemented in IP multicast, which is often employed in Internet

Protocol (IP) applications of streaming media and Internet television. In IP multicast the

implementation of the multicast concept occurs at the IP routing level, where routers create optimal

distribution paths for datagrams sent to a multicast destination address.

**** 4. Anycast ******

Anycast is a network addressing and routing methodology in which datagrams from a single sender

are routed to the topologically nearest node in a group of potential receivers, though it may be sent

to several nodes, all identified by the same destination address.

On the Internet, anycast is usually implemented by using Border Gateway Protocol to simultaneously

announce the same destination IP address range from many different places on the Internet. This

results in packets addressed to destination addresses in this range being routed to the "nearest"

point on the net announcing the given destination IP address.

**** 5. Geocast ******

Geocast refers to the delivery of information to a group of destinations in a network identified by

their geographical locations. It is a specialized form of multicast addressing used by some routing

protocols for mobile ad hoc networks.

A geographic destination address is expressed in three ways: point, circle (with center point and

radius), and polygon (a list of points, e.g., P(1), P(2), …, P(n–1), P(n), P(1)). A geographic router (Geo

Router) calculates its service area (geographic area it serves) as the union of the geographic areas

covered by the networks attached to it. This service area is approximated by a single closed polygon.

Geo Routers exchange service area polygons to build routing tables. The routers are organized in a

hierarchy.

-------------------------------------------------------------------------------------------------------------

8. Frame Relay

- je jedan od najpopularnijih protokola za prenos podataka (uz Eternet i ATM).[1] Koristi za

povezivanje LAN, SNA, Internet ili čak "glasovnih" aplikacija. Frame Relay je pojednostavljena forma

komutacije paketa u kome se sinhroni okviri podataka usmeravaju k različitim odredištima zavisno od

informacija sadržanih u zaglavlju okvira. Uprkos velikoj brzini usmeravanja paketa s kraja na kraj,

Frame Relay nema garancije za integritet podataka

---------------------------------------------------------------------------------------------------------

9. UREĐAJI RASPOREDJENI PO LAYERIMA (koji uređaj/uređaji radi/rade na kom layeru (nivou) )

1. LAYER 1 - Fizički Sloj:

- Hub

- Repeater

Collisions are only an issue with hubs and not with switches.

2. LAYER 2 - Sloj veze:

( MAC adrese kod ethernet mrežnih uređaja) i komunikacija na ovome nivou je moguća samo unutar

lokalnih mreža

- Switch (Komutatori)

CDP nalazi samo susede na Layeru 2!

The Ethernet interfaces also have Layer 2 Ethernet MAC addresses

Some layer 2 network devices are able to divide the collision domains.

3. Layer 3 - Sloj mreže:

(ime.domen.vršni_domen (npr. sr.wikipedia.org);

-Router

A router is considered a Layer 3 device because its primary forwarding decision is based on the

information in the Layer 3 IP packet, specifically the destination IP address. This process is known as

routing.

Interface has a Layer 3 IP address and subnet mask.

Broadcast domains are only divided by layer 3 network devices such as routers or layer 3 switches.

>>> KOji su to Switchevi na Layeru 3: - Lejer 3 svičevi su svičevi koji mogu i da rutiraju na lejeru 3. To

je otprilike kao da imaš ruter sa 24 porta, ali bolje. Videćeš, radićemo ih iz trojke. <<<

4. Layer 4 - Transportni sloj

( protokola na transportnom sloju su TCP i UDP. Ako se neki paket "izgubi" na putu, TCP će tražiti da

se ponovo pošalje, pa je stoga pogodan za razmjenu podataka za koje je integritet podatak na višem

nivou od brzine prijenosa. S druge UDP nema kontrolu da li se poneki paket zagubio, pa je zgodan za

multimedijalne aplikacije, gdje nije toliko bitno da li se zagubi poneki paket, nego je bitna brzina

komunikacije. )

5. Layer 5 - Sloj Sesije

( kod videa preko interneta, gdje ne želimo imati ton bez slike, ili sliku bez tona, ili

oboje ali bez sinhronizacije. Za to se brine ovaj sloj )

6. Layer 6 - Sloj Prezentacije

(txt datoteke na Mac-u, juniksu i Windows-ima na različite načine označavaju

prelazak u novi red. Sve takve konverzije se izvode (ukoliko su implementirane) na

prezentacionom sloju )

7. Layer 7 - Sloj Aplikacije

---------------------------------------------------------------------------------------------

10. ATM

(engl. Asynchronous Transfer Mode) tehnika je prenosa u telekomunikacijama koja se zasniva na

asinhronom vremenskom multipleksiranju odsečaka prometa (ćelija) veličine 53 bajta, od kojih je 48

koristan promet, a 5 čini zaglavlje.

Glavna odlika ove tehnike je da osim prenosa podataka omogućava i kvalitetan prenos drugih vrsta

saobraćaja, kao što su digitalizovani glas (telefon) i slika (video). To je jedan od razloga za korišćenje

ATM-a kod usluga zasnovanih na ADSL-u.

ATM je postao popularan 1990-tih zahvaljujući telefonskim kompanijama i pojedinim proizvođačima

računara. Međutim, na kraju te decenije, drugi proizvodi bazirani na internet protokolima su imali

bolji odnos cena/performanse, pa je uticaj ATM-a vremenom slabio.

-------------------------------------------------------------------------------------------------------

11. Subnetting

Podela IP adresa na manje mreze (subneting, sabneting)

You may recall that a supernet is always a route summary, but a route summary is not always a

supernet.

It is possible that a router could have both a specific route entry and a summary route entry covering

the same network.

>>> Zašto IP adresa kad je tu MAC adresa: - IP adrese su za razliku od MAC hierarhijski organizovane.

Kako bi izgledala ruting tabela sa rutama na osnovu MAC? Morala bi da sadrži svaki mogući MAC, jer

ne postoji način za grupisanje. <<<

Klasne mreze i namena netmaski

Originalni dizajn IP adresa prepoznaje nekoliko razlicitih klasa IP adresa. Ove klase razlikuju se kako

po svojoj velicini (A, B, C), tako i po svojoj nameni (D, E). Za potrebe subnettinga, potrebano je

razumeti razlike u velicini. Dakle, necemo se baviti drugim razlikama izmedju IP adresa.

Osnovne klase IP adresa su:

A: Osnovna maska: 255.0.0.0 (8 bita), opseg: 1.0.0.0 do 126.0.0.0, broj mreza: 2 na 7 - 2

B: Osnovna maska: 255.255.0.0 (16 bita), opseg: 128.1.0.0 do 191.254.0.0, broj mreza: 2 na 14 - 2 -

65,534 host addresses

C: Osnovna maska: 255.255.255.0 (24 bita), opseg: 191.0.1.0 do 223.255.254.0, broj mreza: 2 na 21 –

2 - 254 host addresses

Ako uzmemo u obzir da je moguci broj IP adresa preko 2000000000 i da su sve 32bitne, ako bi svaki

uredjaj na mrezi znao putanju do svih adresa, dolazimo do problema da uredjaji moraju da imaju

stravicno mnogo memorije da bi imali sve te informacije. Posebno sto pored same adrese moraju

imati i podatke o putanji. Kako resiti ovaj problem?

Odgovor je netmaskama. Netmaske su nacin da se na jednostavan nacin referencira vise IP adresa.

Kako netmaske funkcionisu? Pogledajmo primer jedne IP adrese:

212.54.211.1

Predstavljena binarno, ova adresa je: 11010100.00110110.11010011.00000001

Predpostavimo da je to IP adresa naseg racunara [B] u gornjem primeru. Neka su [C], [D] ... svi

uvecani za 1. Dakle, imamo:

B: 212.54.211.1

C: 212.54.211.2

D: 212.54.211.3

...

Z: 212.54.211.254

Pogledom na masku iznad vidimo da njom "pokrivamo" 256 adresa. Sta ukoliko nasa mreza ima

manje racunara? Ovde dolazimo do osnovnog problema kojim se ova poruka bavi - subnettingom.

Subnetting (neki nakaradan prevod na nas jezik bi mogao da bude podmrezavanje) je proces kojim se

iz default "host polja" pozajmljuje odredjeni broj bitova i dodaje masci, kako bi se mreza podelila na

manje funkcionalne (administrativne) celine.

Recimo da se u nasem primeru iznad, krajnja mreza sastoji od pedeset racunara sa adresama

212.54.211.1 - 212.54.211.50. U tom slucaju, preko 200 adresa sa default maskom bi bilo

neupotrebljeno. Ovaj problem se moze resiti tako sto bi se mreza podelila u subnete.

Najmanji subnet koji moze da opsluzi 50 racunara je od 64 adrese (26). Iznad sam spomenuo da je

subnetting proces pozajmljivanja bitova iz host polja i dodavanja masci. Dakle, da bismo imali subnet

od 64 adrese, nama je potrebno 6 umesto 8 bitova za host. Dakle, masci treba dodati 2 bita.

------------------------------------------------------------------------------------------------------------

12. Ethernet

Етернет (енгл. Ethernet) je protokol i najkorišćenija višemedijumska tehnologija lokalnih računarskih

mreža, opisana velikim brojem IEEE 802.3 standarda, koji definišu tehnologije fizičkog i sloja veze

referentnog OSI modela. Isprva je izvedena u topologiji magistrale na zajedničkom koaksijalnom

kablu sa protokolom koji dinamički određuje kako računari pristupaju mreži (CSMA/CD). Eternet

danas širi svoj opseg primenljivosti na MAN i WAN mreže, ima topologiju zvezde ili stabla, dok kao

medijum koristi bakarne i optičke kablove. Pored osnovne funkcije deljenja zajedničkih resursa u

lokalnoj mreži, ima i funkcije pristupa (internetu), okosince među mrežama i distribucije podataka na

veće udaljenosti. Eternet definiše kako se stanice vezuju na računarsku mrežu, tehnologiju koja se

koristi za prenos signala, potom način kako stanice pristupaju datoj mreži, brzinu prenosa, način

signalizacije i kodiranja informacija, kao i veličinu i format paketa informacije koji se koristi pri

komunikaciji.

-------------------------------------------------------------------------------------------------------------

13. MAN

Gradska računarska mreža ili MAN (engl. Metropolitan area network - MAN) predstavlja tip mreže na

osnovu podele računarskih mreža prema prostoru koji obuhvataju. Radi se o mrežama koje

obuhvataju veće oblasti, najčešće na nivou grada (npr. povezuje poslovnice jedne banke u celom

gradu). Najčeće tehnologije koje se koriste pri povezivanju stanica ili manjih mreža (lokalnih mreža)

su tehnologije bežičnog prenosa informacija ili optičkim vlaknima. Ove mreže su poznate još pod

nazivima MAN, gradske mreže ili mreže gradskog područja.

----------------------------------------------------------------------------------------------------------

14. Split-horizon route

In computer networking, split-horizon route advertisement is a method of preventing routing loops

in distance-vector routing protocols by prohibiting a router from advertising a route back onto the

interface from which it was learned. Thus when a device that participates in such route

advertisements receives an update from an interface, it (the device) does not forward updates

through the same interface out. By doing so, routing loops are prevented.

Iz Materijala:

The split horizon rule says that a router should not advertise a network through the interface from

which the update came.

----------------------------------------------------------------------------------------------------------

15. Load balancing

- is a computer networking method for distributing workloads across multiple computing resources,

such as computers, a computer cluster, network links, central processing units or disk drives. Load

balancing aims to optimize resource use, maximize throughput, minimize response time, and avoid

overload of any one of the resources. Using multiple components with load balancing instead of a

single component may increase reliability through redundancy. Load balancing is usually provided by

dedicated software or hardware, such as a multilayer switch or a Domain Name System server

process.

***

The routing table will contain the single destination network but will have multiple exit interfaces,

one for each equal cost path. The router will forward packets using the multiple exit interfaces listed

in the routing table.

If configured correctly, load balancing can increase the effectiveness and performance of the

network. Equal cost load balancing can be configured to use both dynamic routing protocols and

static routes.

Equal Cost Paths and Unequal Cost Paths

Just in case you are wondering, a router can send packets over multiple networks even when the

metric is not the same if it is using a routing protocol that has this capability. This is known as

unequal cost load balancing. EIGRP (as well as IGRP) are the only routing protocols that can be

configured for unequal cost load balancing.

----------------------------------------------------------------------------------------------------------

16. Koji kablovi se kad koriste

1) A router Ethernet interface usually uses an RJ-45 jack that supports unshielded twisted-pair (UTP)

cabling.

When a router is connected to a switch, a straight-through cable is used.

When two routers are connected directly through the Ethernet interfaces, or when a PC NIC is

connected directly to a router Ethernet interface, a crossover cable is used.

----------------------------------------------------------------------------------------------------------

17. MAC addresses

- are used on LAN interfaces, such as Ethernet, and are not used on WAN interfaces. However, WAN

interfaces use their own Layer 2 addresses depending on the technology. Layer 2 WAN encapsulation

types and addresses

----------------------------------------------------------------------------------------------------------

18. RIP Protokol rutiranja

Metrika:

RIP, use simple hop-count, which the number of routers between a router and the destination

network.

Other routing protocols, such as OSPF, determine the shortest path by examining the bandwidth of

the links, and using the links with the fastest bandwidth from a router to the destination network.

The best path to a network is the path with the lowest metric

Speed is technically not an accurate description of bandwidth because all bits travel at the same

speed over the same physical medium. Bandwidth is more accurately defined as the number of bits

that can be transmitted over a link per second.

----------------------------------------------------------------------------------------------------------

19. Metrika (metric) - uopšteno šta je, i ko šta korsiti

A metric is a value used by routing protocols to assign costs to reach remote networks. The metric is

used to determine which path is most preferable when there are multiple paths to the same remote

network.

Each routing protocol uses its own metric.

For example, RIP uses hop count, EIGRP uses a combination of bandwidth and delay, and Cisco's

implementation of OSPF uses bandwidth. Hop count is the easiest metric to envision. The hop count

refers to the number of routers a packet must cross to reach the destination network.

Metrics used in IP routing protocols include:

Hop count - A simple metric that counts the number of routers a packet must traverse

Bandwidth - Influences path selection by preferring the path with the highest bandwidth

Load - Considers the traffic utilization of a certain link

Delay - Considers the time a packet takes to traverse a path

Reliability - Assesses the probability of a link failure, calculated from the interface error count or

previous link failures

Cost - A value determined either by the IOS or by the network administrator to indicate preference

for a route. Cost can represent a metric, a combination of metrics or a policy.

The metric for each routing protocol is:

RIP: Hop count - Best path is chosen by the route with the lowest hop count.

IGRP and EIGRP: Bandwidth, Delay, Reliability, and Load - Best path is chosen by the route with the

smallest composite metric value calculated from these multiple parameters. By default, only

bandwidth and delay are used.

IS-IS and OSPF: Cost - Best path is chosen by the route with the lowest cost. . Cisco's implementation

of OSPF uses bandwidth. IS-IS is discussed in CCNP.

----------------------------------------------------------------------------------------------------------

20. Load balancing - load balansing

The router "load balances" between these equal cost paths. The packets are forwarded using all

equal-cost paths.

Load balancing is in effect if two or more routes are associated with the same destination.

Load balancing can be done either per packet or per destination. How a router actually load balances

packets between the equal-cost paths is governed by the switching process.

EIGRP is also capable of load balancing across unequal-cost paths.

-------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------------------

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--------------------------------------------------------------------------------------------------------------

---- ******* K O M A N D E *** --------- ******* K O M A N D E *** -------**** K O M A N D E ***

------------------------------------------------------------------------------------------------------------

100.

Destet Najbitnih komandi Cisco IOS-a

******************************************************

The Cisco IOS provides thousands of commands, and configuring it can be challenging. Here are 10

commands you need to know, inside and out, when using the Cisco IOS.

#1: The “?”

It may seem entirely too obvious that you should know how to type ? to ask for help when using the

Cisco IOS. However, the Cisco IOS is completely different from other operating systems when it

comes to using the question mark (help key). As the IOS is a command-line operating system with

thousands of possible commands and parameters, using the ? can save your day.

You can use the command in many ways. First, use it when you don’t know what command to type.

For example, type ? at the command line for a list of all possible commands. You can also use ? when

you don’t know what a command’s next parameter should be. For example, you might type show ip ?

If the router requires no other parameters for the command, the router will offer CR as the only

option. Finally, use ? to see all commands that start with a particular letter. For example, show c? will

return a list of commands that start with the letter c.

#2: show running-configuration

The show running-config command shows the router, switch, or firewall’s current configuration. The

running-configuration is the config that is in the router’s memory. You change this config when you

make changes to the router. Keep in mind that config is not saved until you do a copy running-

configuration startup-configuration. This command can be abbreviated sh run.

The show running-config command shows the current configuration of this interface. When the

interface is disabled, the running-config command displays shutdown; however, when the interface

is enabled, no shutdown is not displayed.

#3: copy running-configuration startup-configuration

This command will save the configuration that is currently being modified (in RAM), also known as

the running-configuration, to the nonvolatile RAM (NVRAM). If the power is lost, the NVRAM will

preserve this configuration. In other words, if you edit the router’s configuration, don’t use this

command and reboot the router–those changes will be lost. This command can be abbreviated copy

run start. The copy command can also be used to copy the running or startup configuration from the

router to a TFTP server in case something happens to the router.

#4: show interface

The show interface command displays the status of the router’s interfaces. Among other things, this

output provides the following:

Interface status (up/down)

Protocol status on the interface

Utilization

Errors

MTU

This command is essential for troubleshooting a router or switch. It can also be used by specifying a

certain interface, like shint fa0/0.

#5: show ip interface (brief)

Even more popular than show interface are show ip interface and show ip interface brief. The show

ip interface command provides tons of useful information about the configuration and status of the

IP protocol and its services, on all interfaces. The show ip interface brief command provides a quick

status of the interfaces on the router, including their IP address, Layer 2 status, and Layer 3 status.

#6: config terminal, enable, interface, and router

Cisco routers have different modes where only certain things can be shown or certain things can be

changed. Being able to move between these modes is critical to successfully configuring the router.

For example, when logging in, you start off at the user mode (where the prompt looks like >). From

there, you type enable to move to privileged mode (where the prompt looks like #). In privileged

mode, you can show anything but not make changes. Next, type config terminal (or config t) to go to

global configuration mode (where the prompt looks like router(config)# ). From here, you can change

global parameters. To change a parameter on an interface (like the IP address), go to interface

configuration mode with the interface command (where the prompt looks like router(config-if)#).

Also from the global configuration mode, you can go into router configuration using the router

{protocol} command. To exit from a mode, type exit.

#7: no shutdown

The no shutdown command enables an interface (brings it up). This command must be used in

interface configuration mode. It is useful for new interfaces and for troubleshooting. When you’re

having trouble with an interface, you may want to try a shut and no shut. Of course, to bring the

interface down, reverse the command and just say shutdown. This command can be abbreviated no

shut.

#8: show ip route

The show ip route command is used to show the router’s routing table. This is the list of all networks

that the router can reach, their metric (the router’s preference for them), and how to get there. This

command can be abbreviated shipro and can have parameters after it, like shiproospf for all OSPF

routers. To clear the routing table of all routes, you do clear ip route *. To clear it of just one route,

do clear ip route 1.1.1.1 for clearing out that particular network.

#9: show version

The show version command gives you the router’s configuration register (essentially, the router’s

firmware settings for booting up), the last time the router was booted, the version of the IOS, the

name of the IOS file, the model of the router, and the router’s amount of RAM and Flash. This

command can be abbreviated shver.

#10: debug

The debug command has many options and does not work by itself. It provides detailed debugging

output on a certain application, protocol, or service. For example, debug ip route will tell you every

time a router is added to or removed from the router.

5. show ip protocols

This command shows the routing protocols used in the router and what networks are these protocols

advertising. It also shows the sources of routing updates received at this router. It is very useful in

routing issues troubleshooting.

4. show ip route

This command shows the routing table. This table helps you in finding out the next hop for each and

every routable packet. It is the first indicator to point a problem in routing.

8. show cdp neighbor detail

This command displays detailed information about the neighboring devices like IP addresses,

platforms, and host names. This command can be useful in troubleshooting connectivity issues, and

also can be used in finding out how devices are connected to each other when you have no clear

drawn network map.

CDP operates at Layer 2 only. Therefore, CDP neighbors are Cisco devices that are directly connected

physically and share the same data link.

10. show flash or show slot0:

This command is used to view the contents of the flash and the size of the IOS file(s) and the size of

the flash and how much of it is free. It is necessary in upgrading or installing the IOS file.

11. show arp: Can't ping a neighbor? Make sure you're getting an arp entry.

12. show port: Similar to the show interface command on routers, this command gives you the status

of ports on a SWITCH.

13. show vlan:

With the trend toward having lots of VLANs, check this command to make sure your ports are in the

VLANs you think they are. Its output is very well designed.

14. show tech-support:

This command is great for collecting a lot of info. It basically runs a whole bunch of other show

commands, and spits out dozens of pages of detailed output, designed to be sent to technical

support. But, it's also useful for other purposes.

--- I ja ću da dodam neke: ---

15. erase startup-config and confirm

Clear any existing configuration by issuing the command erase startup-config and confirm.

16. reload

Restart the router.

17. copy running-config startup-config

Enter the command copy running-config startup-config to save the configured changes to NVRAM

18. Bazična konfiguracija

I) The enable command is used to enter the privileged EXEC mode. This mode allows the user to

make configuration changes on the router. The router prompt will change from a ">" to a "#" in this

mode.

--------------------------------------------------------------------

19. K

----------------------------------------------------------------------

20. R1#show interfaces fastethernet 0/0

view the same information, but for a specific interface, such as FastEthernet 0/0, use the show

interfaces command with a parameter that specifies the interface

----------------------------------------------------------------------------------------------------------

20. Kako ruter, kad mu stigne paket odlučuje i proverava šta treba da radi:

One of three path determinations results from this search:

Directly Connected Network - If the destination IP address of the packet belongs to a device on a

network that is directly connected to one of the router's interfaces, that packet is forwarded directly

to that device. This means that the destination IP address of the packet is a host address on the same

network as this router's interface.

Remote Network - If the destination IP address of the packet belongs to a remote network, then the

packet is forwarded to another router. Remote networks can only be reached by forwarding packets

to another router.

No Route Determined - If the destination IP address of the packet does not belong to either a

connected or remote network, and if the router does not have a default route, then the packet is

discarded. The router sends an ICMP unreachable message to the source IP address of the packet.

----------------------------------------------------------------------------------------------------------

21. Access list (akces lista) - Access liste služe za opis saobraćaja. Kada naiđe neki paket prolazi se

kroz access listu kao kroz pravila firewalla od prvog pravila do poslednjeg i proverava gde se mečuje

paket koji je naišao. Permit i deny se uzimaju u obzir tek ako se paket poklapa sa opisom koji je dat u

tom redu. Na primer:

access-list 1 deny 192.168.1.0

access-list 1 permit any

Pošto je access-list 1 u obe naredbe to znači da su u istoj listi koja se zove lista 1 oba pravila. Ako

naiđe paket sa adrese 192.168.1.0 paket će se blokirati, ako je lista primenjena na firewallu. Za sve

ostale adrese prvi red ne pasuje i prelazi se na drugi. Drugi red kaže "dozvoli bez obzira koja je

adresa" - permit any

----------------------------------------------------------------------------------------------------------

22. Administrativni domen -

----------------------------------------------------------------------------------------------------------

23.

----------------------------------------------------------------------------------------------------------

24. Parent route & Child route, Lev 1 and Lev 2, Ultimate Route, Default Route

• Level 1 route - is a network route, a default route, or a supernet route. It is also called an

ultimate route.

• Level 2 route - is a subnetted route with a greater than classful subnet mask, it is also a called a

child route.

• Parent route - is a classful route, but it is not an ulltimate route. A parent route has subnetted child

routes. If there are no child routes there is no parent route. Parent routes do not have an exit

interface or next hop IP address. A parent route is also called a level 1 route.

• Child route - A child route is a subnetted route, where the subnet mask is greater than the classful

subnet mask (eg. /27 versus /24). A child route is a level 2 route.

• Ultimate route - an ultimate route is a route that has an exit interface or a next hop IP address.

• Default Route - also known as a "gateway of last resort," is a route configured to the 0.0.0.0 /0

network and mask. This route does not have to qualify or "match" the destination network therefore

it is a match for all destinations.

***

Ili iz nekog drugog ugla:

There are several types of routes that can be identified in the Cisco routing table.

Level 1 route – route with a subnet mask equal to or less than the classful mask of the network

address.

A level 1 route can function as a:

Default route – static route with the address 0.0.0.0/0.

Supernet route – network address with a mask less than the classful mask.

Network route – has a subnet mask equal to the classful mask. A network route can also be a parent

route.

The level 1 route can be further defined as an ultimate route.

An ultimate route is a route that includes:

either a next-hop IP address (another path)

and/or an exit interface.

And further:

A level 1 parent route or simply only parent route is a network route that does not contain a next-

hop IP address or exit interface for any network.

A level 2 route is a route that is a subnet of a classful network address.

Level 2 child routes are also considered ultimate routes because they will contain the next-hop IP

address and/or exit interface.

If there is only a single level 2 child route and that route is removed, the level 1 parent route will be

automatically deleted. A level 1 parent route exists only when there is at least one level 2 child route.

Regardless of the addressing scheme used by the network (classless or classful), the routing table will

use a classful scheme.

• Network Route - is a level one, ultimate route with an exit interface.

Parent routes do not contain next-hop IP address or exit interface. Just search lines without these

information. Little help, commonly you can find expressions as “is subnetted” or “is variably

subnetted”. Only network routes can be parent routes.

So these are routes that are tabbed. Level 2 routes are also called child routes.

All level 2 routes are always ultimate routes. Level 1 routes are ultimate, if they contain next hop IP

address or exit interface or both (don’t have “is subnetted” or “is variably subnetted”).

----------------------------------------------------------------------------------------------------------

25. #show interfaces brief - šta znače oznake - up, down, administratively down, stanje interfejsa

Interfaces IP-Address OK? Method Status Protocol

FastEthernet0/0 192.168.1.5 Yes manual administratively down down ( - line protocol

is down)

Interfaces - koji je interface u pitanju

IP-Address - IP adresa dodeljena tom interfejsu može da stoji adresa ili unassigned ako nije jos

dodeljena IP adresa

OK? - služi da se vidi da li je IP Adresa dodeljena interfejsu validna ili nije, tj. "Yes" means that the IP

Address is currently valid. "No" means that the IP Address is not currently valid.

Method - može da bude manual ili NVRAM, kad je manual znači da smo je mi dodali a kad je NVRAM

znači da je konfiguracija učitama iz memorije, tj iz startup-config. Može da stoji i DHCP a to je kad:

DHCP means that the interface is configured by DHCP.

Status - Administratively down means that the interface is currently in the shutdown mode, or

turned off. (Administratively) up znači da je interfejs podignut sa no shutdown komandom.

Protocol - Line protocol is down means, in this case, that the interface is not receiving a carrier signal

from a switch or the hub. This condition may also be due to the fact that the interface is in shutdown

mode. Line protocol is up znači da je i interfejs na drugom kraju kabla proradio.

----------------------------------------------------------------------------------------------------------

26. Administrativna distanca - kod ruting protokola - protokola za rutiranje

Routing Protocol Administrative distance

-----------------------------------------------------------------------------

C Directly connected interface 0

S Static route out an interface 1

S Static route to next-hop address 1

D EIGRP summary route 5

External BGP 20

D EX Internal EIGRP 90

I IGRP 100

O OSPF 110

i IS-IS 115

R Routing Information Protocol (RIP) 120

Exterior Gateway Protocol (EGP) 140

o On Demand Routing (ODR) 160

EX External EIGRP 170

B Internal BGP 200

DHCP-learned 254

Unknown 255

Please note that:-

An administrative distance of 255 will cause the router to disbelieve the route entirely and not use it.

Since IOS 12.2, the administrative distance of a static route with an exit interface is 1. Prior to the

release of 12.2 it was in fact 0.

Only the interface itself has an administrative distance of 0, since a route cannot be less than 1.

Directly connected routes have an administrative distance of 1.

----------------------------------------------------------------------------------------------------------

27. Kablovi - boje kod kablova, kabal

N - Naradžasta puna

n - Naradžasta isprekidana

Z - Zelena puna

z - Zelena isprekidana

P - Plava puna

p - plava isprekidana

B - Braon puna

b - braon isprekidana

1.

Straight - trought Cable

1 2 3 4 5 6 7 8

n N z P p Z b B

i tako sa obe strane

2.

Crossover Cable

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

n N z P p Z b B z Z n P p N b B

Koji se uređaj kako povezuje - kad se koji kabal koristi (koji se kabal kad koristi):

1. PC -> Switch - straight through

2. PC -> Hub - straight-through

3. Switch -> Router - straight through

4. PC -> Ruter - crossover cable, ako je auto-sense onda može i straight through

5. Ruter i Ruter - crossover cable

6. switch -> switch - crossover cable

7. PC -> PC - crossover cable

8. Hub i switch - cross over cable

9. bridges and switches - cross over

Iz Materijala:

Straight-through cables are used for:

Switch-to-router

Switch-to-PC

Hub-to-PC

Hub-to-server

Crossover cables are used for:

Switch-to-switch

PC-to-PC

Switch-to-hub

Hub-to-hub

Router-to-router

Router-to-server

Rollover cable - (also known as Cisco console cable or a Yost cable) is a type of null-modem cable that

is often used to connect a computer terminal to a router's console port. This cable is typically flat

(and has a light blue color) to help distinguish it from other types of network cabling. It gets the

name rollover because the pinouts on one end are reversed from the other, as if the wire had been

rolled over and you were viewing it from the other side.

v.35 Kabal - koristi se za povezivanje rutera.

The WAN Physical layer describes the interface between the data terminal equipment (DTE) and the

data circuit-terminating equipment (DCE). Generally, the DCE is the service provider and the DTE is

the attached device.

Serial interfaces require a clock signal to control the timing of the communications. In most

environments, the service provider (a DCE device such as a CSU/DSU) will provide the clock. By

default, Cisco routers are DTE devices. Although Cisco serial interfaces are DTE devices by default,

they can be configured as DCE devices.

You can also distinguish DTE from DCE by looking at the connector between the two cables. The DTE

cable has a male connector, whereas the DCE cable has a female connector.

----------------------------------------------------------------------------------------------------------

28. Poruka posle konfigurisanja i paljenja interfejsa

*Mar 1 01:16:08.212: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up

*Mar 1 01:16:09.214: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed

state to up

The first changed state to up message indicates that, physically, the connection is good. If you do not

get this first message, be sure that the interface is properly connected to a switch or a hub.

Although enabled with no shutdown, an Ethernet interface will not be active, or up, unless it is

receiving a carrier signal from another device (switch, hub, PC, or another router).

The second changed state to up message indicates that the Data Link layer is operational. On LAN

interfaces, we do not normally change the Data Link layer parameters. However, WAN interfaces in a

lab environment require clocking on one side of the link. If you do not correctly set the clock rate,

then line protocol (the Data Link layer) will not change to up. Clock rate command, on the router with

the DCE cable.

----------------------------------------------------------------------------------------------------------

29. #logging synchronous

Kada kucamo komandu i IOS izbacuje neku poruku koja ne utiče na naše kucanje ali nam može

smetati jer ne znamo gde smo stali, da se to ne bi dešavalo uključićemo logging synchronous u #line

console 0 i onde će kopirati celu našu naredbu ispod obaveštenja.

enter line configuration mode for the consoled port and add the logging synchronous command, as

shown. You will see that messages returned by IOS no longer interfere with your typing.



----------------------------------------------------------------------------------------------------------

30. ARP table

Ethernet interface participates in ARP requests and replies and maintains an ARP table. If a router

has a packet destined for a device on a directly connected Ethernet network, it checks the ARP table

for an entry with that destination IP address in order to map it to the MAC address. If the ARP table

does not contain this IP address, the Ethernet interface sends out an ARP request. The device with

the destination IP address sends back an ARP reply that lists its MAC address. The IP address and

MAC address information is then added to the ARP table for that Ethernet interface. The router is

now able to encapsulate the IP packet into an Ethernet frame with the destination MAC address from

its ARP table. The Ethernet frame, with the encapsulated packet, is then sent via that Ethernet

interface.

----------------------------------------------------------------------------------------------------------

31. #show controllers

- command to determine which end of the cable is attached to that interface. In the command

output, notice that R1 has the DCE cable attached to its serial 0/0 interface and that no clock rate is

set.

R1#show controllers serial 0/0/0

Interface Serial0/0/0

Hardware is PowerQUICC MPC860

DCE V.35, no clock

<output omitted>

Znači koristi se da se vidi koji kabal je bocnut u taj serial da li je DTE ili DCE, jer ako je DCE treba da se

konfigurise clock rate.

The available clock rates, in bits per second, are 1200, 2400, 9600, 19200, 38400, 56000, 64000,

72000, 125000, 148000, 500000, 800000, 1000000, 1300000, 2000000, and 4000000

----------------------------------------------------------------------------------------------------------

32. CDP Protokol - Cisco Discovery Protocol

Cisco Discovery Protocol (CDP) is a powerful network monitoring and troubleshooting tool. CDP is an

information-gathering tool used by network administrators to get information about directly

connected Cisco devices. CDP is a proprietary tool that enables you to access a summary of protocol

and address information about Cisco devices that are directly connected. By default, each Cisco

device sends periodic messages, which are known as CDP advertisements, to directly connected Cisco

devices. These advertisements contain information such as the types of devices that are connected,

the router interfaces they are connected to, the interfaces used to make the connections, and the

model numbers of the devices.

CDP provides the following information about each CDP neighbor device:

Device identifiers - For example, the configured host name of a switch

Address list - Up to one Network layer address for each protocol supported

Port identifier - The name of the local and remote port-in the form of an ASCII character string such

as ethernet0

Capabilities list - For example, whether this device is a router or a switch

Platform - The hardware platform of the device; for example, a Cisco 7200 series router

CDP nalazi samo susede na Layeru 2!

************************************************************

Razlika između suseda na Layeru 2 i Layeru 3:

*************************************************************

1. Layer 3 Neighbors

At this point in our topology configuration, we only have directly connected neighbors. At Layer 3,

routing protocols consider neighbors to be devices that share the same network address space.

For example, R1 and R2 are neighbors. Both are members of the 172.16.2.0/24 network. R2 and R3

are also neighbors because they both share the 192.168.1.0/24 network. But R1 and R3 are not

neighbors because they do not share any network address space. If we connected R1 and R3 with a

cable and configured each with an IP address from the same network, then they would be neighbors.

2. Layer 2 Neighbors

CDP operates at Layer 2 only. Therefore, CDP neighbors are Cisco devices that are directly connected

physically and share the same data link. In the CDP Protocol figure, the network administrator is

logged in to S3. S3 will receive CDP advertisements from S1, S2, and R2 only.

Rezime:

***********

Notice the difference between Layer 2 and Layer 3 neighbors. The switches are not neighbors to the

routers at Layer 3, because the switches are operating at Layer 2 only. However, the switches are

Layer 2 neighbors to their directly connected routers.

**********************************************************************************

*********

CDP Naighbours: #show cdp neighbors and #show cdp neighbors detail

CDP provides the following information about each CDP neighbor device:

-Device identifiers - For example, the configured host name of a switch

- Address list - Up to one Network layer address for each protocol supported

- Port identifier - The name of the local and remote port-in the form of an ASCII character string such

as ethernet0

- Capabilities list - For example, whether this device is a router or a switch

- Platform - The hardware platform of the device; for example, a Cisco 7200 series router

The difference between Layer 2 and Layer 3 neighbors. The switches are not neighbors to the routers

at Layer 3, because the switches are operating at Layer 2 only. However, the switches are Layer 2

neighbors to their directly connected routers.

R2#show cdp neighbors (detail) - Switchevi i Ruteri u okolini (smao Cisco uređaji)

R2#show cdp interface - sve interfejse i vremena na koje šalju CDP pakete i Hold timere

R2# show cdp interface Fa0/0 - samo specifičan interfejs, da nam ne pokazuje za sve

R2#show cdp entry R3 - informacije o komšiji R3 (možemo staviti bilo kog kompiju, Swtich ili Ruter)

R2(config)#no cdp run - iskljucivanje razmene CDP paketa, sada gore pomenutim kotrolama nećemo

dobiti nikakve informacije samo će nam se prikazati poruka: % CDP is not enabled

R2(config)#cdp run - ukljucivanje (ukljuceno je po defaultu ali ako se predhodno bio iskljucivao)

ovako se ukljucuje, mora malo da se sačeka dok on razmeni pakete sa kompijama da opet napravi

tabelu

*****

Znači kad treba da ga ugasimo iz sigurnosnih razloga:

If you need to disable CDP globally, for the entire device, use this command:

Router(config)#no cdp run

If you want to use CDP but need to stop CDP advertisements on a particular interface, use this

command:

Router(config-if)#no cdp enable

----------------------------------------------------------------------------------------------------------

33. #telnet IP address

u praksi HQ#telnet 10.0.1.2, je mogu'nost da se telnetuje na ruter ili switch kome ynamo IP adresu, a

mo\emo je saznati i preko komande: HQ#show cdp neighbors detail ili da je ovako znamo. Telnet je

maltene daljinsko povezivanje na uređaj, da se ne bismo povezivali preko Rollover kabla (COM porta

na PC-u), možemo i ovako daljinski sve da podesavamo.

----------------------------------------------------------------------------------------------------------

34. Null interface (nul interfejs, nula interfejs, nulti interfejs)

- as the exit interface. You do not need to enter any commands to create or configure the null

interface. It is always up but does not forward or receive traffic. Traffic sent to the null interface is

discarded.

KOristimu null interfejs kod statičke rute

R2(config)#ip route 192.168.0.0 255.255.0.0 Null0

----------------------------------------------------------------------------------------------------------

35. Diskontinuitet i Kontinuitet u mreži - jako važna stvar za Ripv1

*******

1.

8.0.0.0/16 , 9.0.0.0.0/16 , 10.0.0.0/16 , 11.0.0.0/16 are these networks contiguous?

Odgovor:

8.0.0.0/16 = 8.0.0.0 ~ 8.0.255.255

(8.1.0.0 ~ 8.255.255.255) - addresses left out

9.0.0.0/16 = 9.0.0.0 ~ 9.0.255.255


10.0.0.0/16 = 10.0.0.0 ~ 10.0.255.255


11.0.0.0/16 = 11.0.0.0 ~ 11.0.255.255

So the answer is no, the networks are discontiguous.

*******

2.

8.0.0.0/8 and 195.2.2.0/24 are two different classful networks.

8.0.0.0/8 and 9.0.0.0/8 are two different classful networks as well.

*******

3.

10.0.0.0/16 , 10.1.0.0/16 , 10.2.0.0/16 these are same subnets

of a single same network and all class A. are these also contiguous?

Odgvor:

Yes these are contiguous, as they comprise 10.0.0.0 - 10.2.255.255 range with no addresses left out

*******

4. SLed mreža sa diskontinuitetmo:

8.0.0.0/16

9.0.0.0/16

10.0.0.0/16

11.0.0.0/16

Sled mreža bez diskontinuiteta:

8.0.0.0/8

9.0.0.0/8

10.0.0.0/8

11.0.0.0/8

or

8.1.0.0/16

8.2.0.0/16

8.3.0.0/16

" " " "

" " " "

8.128.0.0/16

" " " "

" " " "

8.192.0.0/16

" " " "

" " " "

8.254.0.0/16

8.255.0.0/16

*******

5. 8.1.0.0/16 <-R1-> 9.0.0.0/16 <-R2-> 10.0.0.0/16 <-R3-> 8.2.0.0/16

This is a "discontiguous" network as we passed through two different "major" networks to get from

one portion of the 8.0.0.0/8 network to the rest of the 8.0.0.0/8 network.

*******

6.

8.0.0.0/16 <-R1-> 9.0.0.0/16 <-R2-> 10.0.0.0/16 <-R3-> 11.0.0.0/16

Is this a contiguous or discontiguous network? While the individual address are indeed

"discontiguous", this network as a whole is "contiguous". Why? Because we did not pass through a

different "major" network to get to another portion of the same "major" network. For example,

8.1.0.0/16 <-R1-> 9.0.0.0/16 <-R2-> 10.0.0.0/16 <-R3-> 8.2.0.0/16

Is this a contiguous or discontiguous network? This is a "discontiguous" network as we passed

through two different "major" networks to get from one portion of the 8.0.0.0/8 network to the rest

of the 8.0.0.0/8 network.

Rezime:

That's a great example. Indeed, a discontiguous network and a discontiguous address space are two

different things. Thank you.

*******

7.

Jedan predlog:

Use binary math to build your networks and you wont go wrong. The idea is to group addresses by

their most significant bits.

If you have:

WEST LAN EAST LAN

10.9.0.0 (00001001) 10.12.0.0 (00001100)

10.8.0.0 (00001000) 10.13.0.0 (00001101)

10.10.0.0 (00001010) 10.14.0.0 (00001110)

10.11.0.0 (00001011) 10.15.0.0 (00001111)

Your have contiguous networks and the router will be look at the most significatn common bits and

advertise summary routes.

WEST EAST

10.8.0.0/14 10.12.0.0/14

If you then go and move 10.15.0.0/16 to WEST you loose the benefit of contiguous networks and

cannot advertise summary routes.

***********

8.

Same Major network ex. :-

8.0.0.0 /8 , 8.2.0.0 /16 , 8.80.50.0/24 (one major network 8.0.0.0 /8)

Different Major netowkr ex:-

8.0.0.0 /8 , 9.0.0.0 /8 ,10.0.0.0/8 (even thought they are all Class A but different major networks)

**********

9.

Znači, ako je:

8.0.0.0/16 <-R1-> 9.0.0.0/16 <-R2-> 10.0.0.0/16 <-R3-> 11.0.0.0/16

Is Contagiuous .

Because we did not pass through a different "major" network to get to another portion of the same

"major" network.

Basically all are different maj. networks

Q1)

8.0.0.0/16 <-R1-> 8.1.0.0/16 <-R2-> 8.2.0.0/16 <-R3-> 9.0.0.0/16<-R4->10.0.0.0/16

Ans: Contiguous Network

Reason :-Because we did not pass through a different "major" network to get to another portion

of the same "major" network.

Q2) 8.0.0.0/24 <-R1-> 10.0.0.0/24 <-R2-> 9.0.0.0/24 <-R3_> 11.0.0.0/24


Reason :-Because we did not pass through a different "major" network to get to another

portion of the same "major" network.

Q3) 8.0.0.0/8 <-R1-> 172.16.5.0/24 <-R2-> 9.1.0.0/16 <-R3->


Reason :-Because we did not pass through a different "major" network to get to another portion

of the same "major" network.

(as per definitiion there has to be same major network at the two ends . One is Class A 8.0.0.0/8

network the other end has Class A 9.0.0.0/8 ; so as the two end network are not part of the same

portion of the same "major" network the above is Contiguous Network .

Q4)Discontiguous network vs Discontiguous Subnet Understanding

Say you have 10.8.0.0/16, 10.9.0.0/16, 10.10.0.0/16, and 10.11.0.0/16. If you own all of these

networks, you could advertise them summarized as 10.8.0.0/14.

However, if you only owned the 10.8, 10.9, and 10.11 network spaces, you could not. You would then

only be able to summarize it down to two routes - 10.8.0.0/15, and 10.11.0.0/16.

Ans : In the above scenario the Network is Contiguous but the subnet are Distcontiguous

**********

Major network ( to define a major network use classful subnetting based on ip)

Same Major network ex. :-

8.0.0.0 /8 , 8.2.0.0 /16 , 8.80.50.0/24 (one major network 8.0.0.0 /8)

172.16.4.0 /24 ; 172.16.240.0 /24; 172.16.5.0 /24 (one major network 172.16.0.0 /16)

Different Major netowkr ex:-

8.0.0.0 /8 , 9.0.0.0 /8 ,10.0.0.0/8 (even thought they are all Class A but different major networks)

as i understand u seeing that 8.0.0.0/8 and 9.1.0.0/16 belong to class A and 172.16.5.0/24 to class B

which is discontining the link between to class A address which is wrong in this concept.

so in this scaenario

8.0.0.0/8 <-R1-> 172.16.5.0/24 <-R2-> 9.1.0.0/16

lets see the major network for the above which is

8.0.0.0/8 172.16.5.0/16 9.0.0.0/8

Network 1 network 2 network 3

three independent major network .

thus contiguous

Because we did not pass through a different "major" network to get to another portion of the same

"major" network

(as Brian explained

ther is difference between a contiguous address space and a contiguous network.

dont look for continous address space look for major network .

in case the scenario changes

8.0.0.0/8 <-R1-> 172.16.5.0/24 <-R2-> 8.5.0.0/16

lets see the major network for the above which is

8.0.0.0/8 172.16.5.0/16 8.0.0.0/8

Network 1 network 2 network 1

so two major network in above scenario

network 1 on either side and network 2 in middle

so the network 2 has inersected the continuity of the network 1 on either side

thus discontiguous network is formed.

----------------------------------------------------------------------------------------------------------

36. Redistribucija - Redistribution routes

******************************************************

Redistribucija ruta

– razmena ruta između različitih protokola rutiranja

• Kada postoji redistribucija

– jedan ruting domen učitava rute iz drugog

– ruteri u jednom ruting domenu znaju putanje do mreža iz drugog ruting domena

– postoji konektivnost i razmena saobraćaja

Often, running different routing protocols is part of a network design.

A multiple protocol environment makes redistribution a necessity.

Differences in routing protocol characteristics (such as metrics, administrative distance classful, and

classless capabilities) can affect redistribution.

For redistribution to be successful, these differences must be considered.

Note: When redistributing between a classful routing protocol (such as Routing Information Protocol

Version 1 [RIP V1], Interior Gateway Routing Protocol [IGRP] ) and a classless routing protocol (such

as Open Shortest Path First [OSPF]), RIP V2, Enhanced Interior Gateway Routing Protocol [EIGRP] )

will not advertise routes out an interface if those routes are on the same major network, but have a

different mask than that particular interface.

Note: When redistributing routes into OSPF, a common mistake is to omit the subnets keyword from

the redistribution statement.

This prevents redistribution from taking place.

When there is mutual redistribution between routing protocols, there is the possibility of creating

routing loops.

A routing loop is when one routing protocol announces a route learned by another routing protocol

through redistribution.

To avoid this, never announce the information originally received from routing process x back into

routing process x.

This can be done with the use of distribution lists or route maps.

-----------

When you redistribute one protocol into another, remember that the metrics of each protocol play

an important role in redistribution. Each protocol uses different metrics. For example, the Routing

Information Protocol (RIP) metric is based on hop count, but Interior Gateway Routing Protocol

(IGRP) and Enhanced Interior Gateway Routing Protocol (EIGRP) use a composite metric based on

bandwidth, delay, reliability, load, and maximum transmission unit (MTU), where bandwidth and

delay are the only parameters used by default. When routes are redistributed, you must define a

metric that is understandable to the receiving protocol.

Zadavanje Metrike:

Način 1:

router rip

redistribute static metric 1

redistribute ospf 1 metric 1

Način 2:

Or you can use the same metric as a default for all redistribution (Using the default-metric command

saves work because it eliminates the need for defining the metric separately for each redistribution.):

router rip

redistribute static

redistribute ospf 1

default-metric 1

------------------------------------

**************

Primer 1:

**************

Ruteri R2 i R5 su oba granična, tj nalaze se na granici, i sa jedne strane imaju Rip a sa druge IGRP.

In the previous topology, R2 and R5 are doing mutual redistribution. RIP is being redistributed into

IGRP and IGRP is being redistributing into RIP, as this configuration shows.

R2:

router igrp 7

network 181.16.0.0

redistribute rip metric 1 1 1 1 1

(bandwith izrađen u Kbits, delay, reliability, load, MTU - Maximum Transmition Unit)

router rip

network 178.1.0.0

redistribute igrp 7 metric 2

(administrativni domen je 7, a hop caount je 2)

R5:

router igrp 7

network 181.16.0.0


router rip

network 178.1.0.0


*******************

Primer 2:

*******************

Sa filterima

R2:

router igrp 7

network 181.16.0.0


distribute-list 1 in s1

router rip

network 178.1.0.0




R5:

router igrp 7

network 181.16.0.0


distribute-list 1 in s1

router rip

network 178.1.0.0




The distribute lists added to the configurations, as shown above, filter any IGRP updates that come

into the serial 1 interface of the routers. If the routes in the updates are permitted by access list 1,

the router accepts them in the update; otherwise it does not. In this example, the routers are being

told that they should not learn network 192.168.1.0 through the IGRP updates they receive on their

serial 1 interface. Therefore, the only knowledge these routers have for network 192.168.1.0 is

through RIP from R1.

I jedan rezime:

This output shows an IGRP/EIGRP router redistributing static, Open Shortest Path First (OSPF), RIP,

and Intermediate System-to-Intermediate System (IS-IS) routes.

router igrp/eigrp 1

network 131.108.0.0

redistribute static

redistribute ospf 1

redistribute rip

redistribute isis

default-metric 10000 100 255 1 1500

IGRP and EIGRP need five metrics when redistributing other protocols: bandwidth, delay, reliability,

load, and MTU, respectively. An example of IGRP metrics follows:

Metric Value

1. bandwidth In units of kilobits per second; 10000 for Ethernet

2. delay In units of tens of microseconds; for Ethernet it is100 x 10 microseconds = 1 ms

3. reliability 255 for 100 percent reliability

4. load Effective load on the link expressed as a number from 0 to 255 (255 is 100

percent loading)

5. MTU Minimum MTU of the path; usually equals that for the Ethernet interface, which

is 1500 bytes

OSPF

***********

This output shows an OSPF router redistributing static, RIP, IGRP, EIGRP, and IS-IS routes.

router ospf 1

network 131.108.0.0 0.0.255.255 area 0

redistribute static metric 200 subnets

redistribute rip metric 200 subnets

redistribute igrp 1 metric 100 subnets

redistribute eigrp 1 metric 100 subnets

redistribute isis metric 10 subnets

The OSPF metric is a cost value based on 10na8/ bandwidth of the link in bits/sec. For example, the

OSPF cost of Ethernet is 10: 108/107 = 10

Note: If a metric is not specified, OSPF puts a default value of 20 when redistributing routes from all

protocols except Border Gateway Protocol (BGP) routes, which get a metric of 1.

----------------------------------------------------------------------------------------------------------

37. NBMA

*******************************

- non-broadcast multiple access network: is a computer network to which multiple hosts are

attached, but data is transmitted only directly from one computer to another single host over a

virtual circuit or across a switched fabric. NBMA networks do support multicast or broadcast traffic

manually (pseudo-broadcasts). Some common examples of nonbroadcast network technologies

include Asynchronous Transfer Mode (ATM), Frame Relay, X.25, and home power line networking.

----------------------------------------------------------------------------------------------------------

38.Routing Protocol

*******************************

- A routing protocol is a set of processes, algorithms, and messages that are used to exchange routing

information and populate the routing table with the routing protocol's choice of best paths

----------------------------------------------------------------------------------------------------------

39. Wildcard mask

*******************************

A wildcard mask is a mask of bits that indicates which parts of an IP address are available for

examination. In the Cisco IOS, they are used in several places, for example:

To indicate the size of a network or subnet for some routing protocols, such as OSPF.

To indicate what IP addresses should be permitted or denied in access control lists (ACLs).

A wildcard mask can be thought of as an inverted subnet mask. For example, a subnet mask of

255.255.255.0 (binary equivalent = 11111111.11111111.11111111.00000000) inverts to a wildcard

mask of 0.0.0.255.

Any wildcard bit-pattern can be masked for examination: For example, a wildcard mask of 0.0.0.254

(binary equivalent = 00000000.00000000.00000000.11111110) will allow even-numbered IP

addresses to be examined. A 0 octet in the wildcard mask indicates that the corresponding octet in

the network must match exactly. On the other hand, a 254 indicates that you don't care what the

corresponding octet is in the network except for the host(255) bit.

A network and wildcard mask combination of 1.1.1.1 0.0.0.0 would match an interface configured

exactly with 1.1.1.1 only, and nothing else. This is really useful if you want to activate OSPF on a

specific interface in a very clear and simple way.

If you insist on matching a range of networks, the network and wildcard mask combination of 1.1.0.0

0.0.255.255 would match any interface in the range of 1.1.0.0 to 1.1.255.255. Because of this, it's

simpler and safer to stick to using wildcard masks of 0.0.0.0 and identify each OSPF interface

individually, but once configured, they function exactly the same- one way is not better than the

other.

Wildcard masks are used in situations where subnet masks may not apply. For example, when two

affected hosts fall in different subnets, the use of a wildcard mask will group them together.

----------------------------------------------------------------------------------------------------------

40. Sumarizacija ruta - Route Summarization, sumarne rute, supernet

**********************************************************************************

***********

Supernet is an aggregation of multiple major classful network addresses.

--- Sumarizacije statičkih ruta ---

Multiple static routes can be summarized into a single static route if:

1. The destination networks can be summarized into a single network address, and

2. The multiple static routes all use the same exit-interface or next-hop IP address

Postupak kreiranja/pravljenja/izvođenja sumarne rute, postupno, preko binarnog zapisa:

Calculating a summary route

Here's the process of creating the summary route 172.16.0.0/22, as shown in the figure:

1. Write out the networks that you want to summarize in binary.

2. To find the subnet mask for summarization, start with the left-most bit.

3. Work your way to the right, finding all the bits that match consecutively.

4. When you find a column of bits that do not match, stop. You are at the summary boundary.

5. Now, count the number of left-most matching bits, which in our example is 22. This number

becomes your subnet mask for the summarized route, /22 or 255.255.252.0

6. To find the network address for summarization, copy the matching 22 bits and add all 0 bits to the

end to make 32 bits.

By following these steps, we can discover that the three static routes on R3 can be summarized into a

single static route, using the summary network address of 172.16.0.0 255.255.252.0:

CIDR allows for supernetting. A supernet is a group of major network addresses summarized as a

single network address with a mask less than that of the default classful mask.

Summary routes can be used by both static routes and classless routing protocols. Classful routing

protocols can only summarize routes to the default classful mask.

Razlika između superneta i sumarne rute:

You may recall that a supernet is always a route summary, but a route summary is not always a

supernet.

It is possible that a router could have both a specific route entry and a summary route entry covering

the same network.

----------------------------------------------------------------------------------------------------------

41. Subnet Maska ili Subnet Musk

**************************************************************

Subnet mask in the route entry is what determines how many bits must match the packet's

destination IP address for this route to be a match.

-------------------------------------------------------------------------------------------------------------

42. ISP network - Internet Service Provider

**************************************************************

An Internet Service Provider (also known as an ISP or even as an IAP, internet access provider) is a

firm that offers subscribers access to the internet. This internet service provider maintains large runs

of cabling and maintains network services in order to transfer and deliver web content to those

paying the subscription fee. Typically, these internet service providers focus on DSL, Cable modem,

wireless, and more recently, dedicated high-speed interconnects such as T1 or fiber optic service

(typically abbreviated Fios).

Maltene: An ISP is a company that supplies Internet connectivity to home and business customers.

ISPs support one or more forms of Internet access, ranging from traditional modem dial-up to DSL

and cable modem broadband service to dedicated T1/T3 lines.

-------------------------------------------------------------------------------------------------------------

43. Autonomous system (AS) - otherwise known as a Routing Domain

**********************************************************************************

*********** *********************

- is a collection of routers under a common administration. Typical examples are a company's

internal network and an Internet service provider's network. Because the Internet is based on the

autonomous system concept, two types of routing protocols are required: interior and exterior

routing protocols. These protocols are:

- Interior Gateway Protocols (IGP) are used for intra-autonomous system routing - routing inside an

autonomous system.

- Exterior Gateway Protocols (EGP) are used for inter-autonomous system routing - routing between

autonomous systems.

-------------------------------------------------------------------------------------------------------------

44. Konvergencija (Convergence) u dinamičkom rutiranju

**********************************************************************************

***********

Convergence is when all routers' routing tables are at a state of consistency.

Convergence time is the time it takes routers to share information, calculate best paths, and update

their routing tables.

Sporo konvergirajući: RIP i IGRP

Brzo konvergirajući: EIGRP i OSPF

-------------------------------------------------------------------------------------------------------------

45. Vreme potrebno za konvergenciju, tj vreme konvergencije:

**********************************************************************************

***********

Routing protocols are compared based on how fast they can propagate this information - their speed

to convergence.

The speed of achieving convergence consists of:

How quickly the routers propagate a change in the topology in a routing update to its neighbors.

The speed of calculating best path routes using the new routing information collected.

-------------------------------------------------------------------------------------------------------------

46. Triger Update (triggered update)

*********************************************

To speed up the convergence when there is a topology change, RIP uses triggered updates. A

triggered update is a routing table update that is sent immediately in response to a routing change.

Triggered updates do not wait for update timers to expire. The detecting router immediately sends

an update message to adjacent routers. The receiving routers, in turn, generate triggered updates

that notify their neighbors of the change.

Triggered updates are sent when one of the following occurs:

- An interface changes state (up or down)

- A route has entered (or exited) the "unreachable" state

- A route is installed in the routing table

There are two problems with triggered updates:

- Packets containing the update message can be dropped or corrupted by some link in the network.

- The triggered updates do not happen instantaneously. It is possible that a router that has not yet

received the triggered update will issue a regular update at just the wrong time, causing the bad

route to be reinserted in a neighbor that had already received the triggered update.

-------------------------------------------------------------------------------------------------------------

47. Ruting tabela - Bliži pogled (Routing Table - Closer Look), stavke u ruting tabeli

**********************************************************************************

**************************

*******************

Level 1 rute:

*******************

A level 1 route is a route with a subnet mask equal to or less than the classful mask of the network

address.

Primer: 192.168.1.0/24 is a level 1 network route, because the subnet mask is equal to the network's

classful mask. /24 is the classful mask for class C networks, such as the 192.168.1.0 network.

A level 1 route can function as a:

- Default route - A default route is a static route with the address 0.0.0.0/0.

- Supernet route - A supernet route is a network address with a mask less than the classful mask.

- Network route - A network route is a route that has a subnet mask equal to that of the classful

mask. A network route can also be a parent route. Parent routes will be discussed in the next section.

The source of the level 1 route can be a directly connected network, static route, or a dynamic

routing protocol.

A level 1 route can be either an ultimate route or a parent route

***************************************

Ultimate route (Ultimat ruta)

***************************************

An ultimate route is a route that includes:

- either a next-hop IP address (another path)

- and/or an exit interface

Primer: C 192.168.1.0/24 is directly connected, Serial0/0/1

R 192.168.1.0/24 [120/1] via 172.16.2.2, 00:00:25, Serial0/0/0

**************************************************************

Roditeljska ruta (Parent Route)

**************************************************************

A level 1 parent route is a network route that does not contain a next-hop IP address or exit interface

for any network.

Parent route is created whenever a route with a mask greater than the classful mask is entered into

the routing table

A level 1 parent route is the classful network address of the subnet route.

Primer: 172.16.0.0/24 is subnetted, 1 subnets

*******************************

Dete ruta (Child Route)

********************************

A level 2 route is a route that is a subnet of a classful network address.

The source of a level 2 route can be a directly connected network, a static route, or a dynamic

routing protocol.

Primer: C 172.16.3.0 is directly connected, FastEthernet0/0

R 172.16.3.0 [120/1] via 172.16.2.2, 00:00:25, Serial0/0/0

Level 2 child routes contain the route source and the network address of the route.

Level 2 child routes are also considered ultimate routes because they will contain the next-hop IP

address and/or exit interface.

If there is only a single level 2 child route and that route is removed, the level 1 parent route will be

automatically deleted. A level 1 parent route exists only when there is at least one level 2 child route.

*********

Regardless of the addressing scheme used by the network (classless or classful), the routing table will

use a classful scheme.

***********

Najduže POklapanje (The Longest Match)

**************************************************************

The subnet mask of the route in the routing table is used to determine the minimum number of left-

most bits that must match.

Remember, an IP packet only contains the IP address and not the subnet mask.

The route with the most number of equivalent left-most bits, or the longest match, is always the

preferred route.

----------------------------------------------

Classless and classful routing behaviors are not the same as classless and classful routing protocols.

**********************************************************************************

****************************

- Classful and classless routing protocols affect how the routing table is populated.

- Classful and classless routing behaviors determine how the routing table is searched after it is

populated.

------------------------------------------------

Classful i Classless ponašanje (classful behavior and classless behavior)

**********************************************************************************

*******************

The routing behavior, specified by the ip classless or no ip classless commands

Podesavanje:

R1(config)#no ip classless

R2(config)#ip classless

Provera:

show running config

Ako je uključeno no ip classless ako posle poklapanja sa Parent rutom i ne poklapanja sa nijednom

Child Rutom neće dalje gledati da li ima možd Default Ruta već će odmah odbaciti paket, čak ni

Supernet rute neće gledati!!!:

- Because router R2 is using classful routing behavior, no ip classless, the router will not search

beyond the child routes for a lesser match.

- The routing table process will not use the default route, 0.0.0.0/0, or any other route.

- A common error is to assume that a default route will always be used if the router does not have

a better route. In our example, R2's default route is not examined nor used, although it is a match.

This is often a very surprising result when a network administrator does not understand the

difference between classful and classless routing behavior.

A ako uključimo ip classless i imamo Default Rutu:

S* 0.0.0.0/0 is directly connected, Serial0/0/1

The mask is /0, which means that zero or no bits need to match. A default route will be the lowest-bit

match. In classless routing behavior, if no other route matches, the default route will match.

Remember - that classful and classless routing behaviors are independent from classful and classless

routing protocols.

A router could be configured with classful routing behavior (no ip classless) and a classless routing

protocol.

A router could also be configured with classless routing behavior (ip classless) and a classful routing

protocol.

*****************

Zaključak je:

*****************

In today's networks, it is recommended to use classless routing behavior so that supernet and default

routes can be used whenever needed.

Question: What happens when there is a match with the parent route but none of the child routes?

Answere:

- If the router is using classful routing behavior, no other routes will be searched and the packet

will be discarded. Classful routing behavior can be implemented using the no ip classless command.

- If there is a match with a parent route but none of the child routes, the routing table process will

continue to search other routes in the routing table including a default route should one exist.

Classless routing behavior is implemented by using the ip classless command.

-------------------------------------------------------------------------------------------------------------

48.

-------------------------------------------------------------------------------------------------------------

49.

-------------------------------------------------------------------------------------------------------------

50.

-------------------------------------------------------------------------------------------------------------

51.

--------------------------------------------------------------------------------------------------------------------------

Neka moja Razmišljanaj:

subneting, subnet maska, broj hostova

Class A: Osnovna maska: 255.0.0.0 (8 bita),

opseg: 1.0.0.0 do 126.0.0.0, broj mreza: 2 na 7 - 2

Class B: Osnovna maska: 255.255.0.0 (16 bita),

opseg: 128.1.0.0 do 191.254.0.0, broj mreza: 2 na 14 - 2

Class C: Osnovna maska: 255.255.255.0 (24 bita),

opseg: 191.0.1.0 do 223.255.254.0, broj mreza: 2 na 21 – 2

Mreža: 8.0.0.0 (uzeta nasumično)

1) /31 - 2 na 1 = 2 1 network, 1 broadcast, 0 valid ip address

255.255.255.254 - 0.0.0.1

8.0.0.0 /31

8.0.0.2 /31

8.0.0.4 /31

8.0.0.6 /31...


255.255.255.252 - 0.0.0.3

8.0.0.0 /30

8.0.0.4 / 30

8.0.0.8 /30

8.0.0.12 /30

8.0.0.16 /30...


255.255.255.248 - - 0.0.0.7

8.0.0.0 / 29

8.0.0.8 /29

8.0.0.16 /29

8.0.0.24 /29

8.0.0.32 /29...

4) /28 - 2 na 4 = 16 1 network, 1 broadcast, 14 valid ip address - 14 host addresses per subnet.

creating 4,096 subnets

255.255.255.240 - 0. 0. 0. 15 (Wildcard mask)

8.0.0.0 /28

8.0.0.16 /28

8.0.0.32 /28

8.0.0.48 /28

8.0.0.64 /28

8.0.0.80 /28...


255.255.255.224 - - 0.0.0.31

8.0.0.0 /27

8.0.0.32 /27

8.0.0.64 /27

8.0.0.96 /27

8.0.0.128 /27

8.0.0.160 /27

8.0.0.0.192 /27

8.0.0.0.224 /27

8.0.1.0 /27

8.0.1.32 /27...


255.255.255.192 - 0.0.0.63

8.0.0.0 /26

8.0.0.64 /26

8.0.0.128 /26

8.0.0.192 /26

8.0.1.0 /26

8.0.1.64 /26

8.0.1.128 /26...


255.255.255.128 - 0.0.0.127

8.0.0.0 /25

8.0.0.128 /25

8.0.1.0 /25

8.0.1.128 /25

8.0.2.0 /25...

-----------

Class C:

-----------

8) /24 - 2 na 8 = 256 1 network, 1 broadcast, 254 valid ip address * 256 subnets with a /24

mask. This mask will allow 254 host addresses per subnet

255.255.255.0 - 0.0.0.255

8.0.0.0 /24 - adresa mreze

8.0.0.1 /24 //subneti

8.0.0.2 /24

8.0.0.3 /24

8.0.0.256 /24 - broadcast

8.0.1.0 /24

8.0.2.0 /24...


255.255.254.0 - 0.0.1.255

8.0.0.0 / 23

8.0.0.1 /24

8.0.0.2 /24

8.0.0.3 /24

***

8.0.0.255 /23

8.0.1.0 /23

***

8.0.1.255 /23

8.0.2.0 /23

8.0.2.1 /23

8.0.2.2 /23

8.0.2.3 /23

***

8.0.2.255 /23

8.0.3.0 /23

***

8.0.2.255 /23

8.0.4.0 /23

8.0.6.0 /23

8.0.8.0 /23..


255.255.252.0 - 0.0.3.255

8.0.0.0 /22

8.0.4.0 /22

8.0.4.1 /22

8.0.4.2 /22

8.0.4.3 /22

***

8.0.4.255 /22

8.0.5.0 /22

***

8.0.7.255 /22

8.0.8.0 /22...


255.255.248.0 - 0.0.7.255

8.0.0.0 /21

8.0.8.0 /21

8.0.16.0 /21...

12) /20 - 2 na 12 = 4098 1 network, 1 broadcast, 4096 valid ip address - 4094 host addresses per

subnet. 16 subnets

255.255.240.0 - 0.0.15.255

8.0.0.0 /20

8.0.16.0 /20

8.0.32.0 /20...


255.255.224.0 - 0.0.31.255

8.0.0.0 /19

8.0.32.0 /19

8.0.64.0 /19...

14) /18 - 2 na 14 = 16.384 1 network, 1 broadcast, 16.382 valid ip address

255.255.192.0 - 0.0.63.255

8.0.0.0 /18

8.0.64.0 /18

8.0.128.0 /18

8.0.256.0 /18

15) /17 - 2 na 15 = 32.768 1 network, 1 broadcast, 32.766 valid ip address

255.255.128.0 - 0.0.127.255

8.0.0.0 /17

8.0.128.0 /17

8.0.256.0 /17

Class B:

16) /16 - 2 na 16 = 65.536

255.255.0.0 - 0.0.255.255

8.0.0.0 /16 - ovo je jedna mreza

8.1.0.0 /16 - II mreza

8.2.0.0 /16 - III mreza

8.3.0.0 /16...

tj. :

10.0.0.0/16

10.1.0.0/16

10.1.1.0/24

10.1.2.0/24

10.1.3.0/24

.

.

.

10.1.255.0/24

10.2.0.0/16

.

.

.

10.255.0.0/16

17) /15 - 2 na 17 = 131.072

8.0.0.0 /16

8.2.0.0 /16

8.4.0.0 /16

8.6.0.0 /16...

18) /14 - 2 na 18 = 262.144

8.0.0.0 /15

8.4.0.0 /15

8.8.0.0 /15

8.16.0.0 /15...

19) /13 - 2 na 19 = 524.288

255.248.0.0

8.0.0.0 /14

8.8.0.0 /14

8.16.0.0 /14

8.24.0.0 /14

8.32.0.0 /14...

20) /12 - 2 na 20 = 1.048.576

*** 255.240.0.0 ***

8.0.0.0 /13

8.16.0.0 /13

8.32.0.0 13

8.64.0.0 /13...

21) /11 - 2 na 21 = 2.097.152

*** 255.224.0.0 ***

8.0.0.0 /12

8.32.0.0 /12

8.64.0.0 /12

8.64.0.1 /12

8.64.0.2 /12

***

8.64.0.255 /12

8.64.1.0 /12

8.64.1.1 /12

***

8.64.1.255 /12

***

8.64.255.255 /12

8.65.0.0 /12

8.64.0.1 /12

***

8.127.255.255 /12

8.128.0.0 /12

8.168.0.0 /12

8.192.0.0 /12

8.224.0.0 /12

8.256.0.0 /12 ????!!!??!?

22) /10 - 2 na 22 =

*** 255.192.0.0 ***

8.0.0.0 /11

8.64.0.0 /11

8.128.0.0 /11

8.192.0.0 /11

8.256.0.0 /11 ?!??!

23) /9 - 2 na 23 =

*** 255.128.0.0 ***

8.0.0.0 /10

8.128.0.0 /10

8.256.0.0 /10

Class A:

24) /8 - 2 na 24 =

255.0.0.0

8.0.0.0 /8

8.256.0.0 /8 ili treba 9.0.0.0 /8

25) /7 - 2 na 25 =

254.0.0.0

8.0.0.0 /7

?.?.?.? /7

??!??!??!??!!

------------------------------------------------------------------------------------------------------------

INternet Protokoli i na kom nivou se koji internet protokol nalazi

-- Spisak Internet Protokola --

Апликациони протоколи:

--Слој 7 ОСИ модела (Layer 7) [уреди]

HTTP (енгл. Hypertext Transfer Protocol)

HTTPS (енгл. Hypertext Transfer Protocol Secure)

FTP (енгл. File Transport Protocol)

TFTP (енгл. Trivial File Transport Protocol)

DNS (енгл. Domain Name Service protocol)

BOOTP (енгл. Bootstrap Protocol)

DHCP (енгл. Dynamic host configuration protocol)

POP (енгл. Post office protocol)

POP3 (енгл. Post office protocol verzija 3)

SMTP (енгл. Simple Mail Transfer Protocol)

SNMP (енгл. Simple Network Management Protocol)

Telnet(енгл. Terminal emulation protocol)

SSH (енгл. Secure shell)

RADIUS (енгл. Remote Authentication Dial In User Service)

RTP (енгл. Real-time Transport Protocol)

Jabber, XMPP (енгл. Extensible Messaging and Presence Protocol)

GNUTELLA (peer-to-peer file sharing protocol)


SMB (енгл. Server Message Block)

ADSP (енгл. AppleTalk Data Stream Protocol)

ASP (енгл. AppleTalk Session Protocol)

ISO-SP (енгл. OSI Session Layer Protocol (X.225, ISO 8327))

NetBIOS (енгл. Network Basic Input Output System)

PAP (енгл. Password Authentication Protocol)

PPTP (енгл. Point-to-Point Tunneling Protocol)

SMPP (енгл. Short Message Peer-to-Peer)

SSH (енгл. Secure Shell)

Транспортни протоколи: [уреди]


TCP (енгл. Transmission Control Protocol)

UDP (енгл. User Datagram Protocol)

CUDP (енгл. Cyclic UDP)

DCCP (енгл. Datagram Congestion Control Protocol)

FCP (енгл. Fiber Channel Protocol)

NBF (енгл. NetBIOS Frames protocol)

SCTP (енгл. Stream Control Transmission Protocol)

SPX (енгл. Sequenced Packet Exchange)

SST (енгл. Structured Stream Transport)

Међумрежни протоколи: [уреди]


IPv4 (енгл. Internet Protocol verzija 4)

IPv6 (енгл. Internet Protocol verzija 6)

IPSec (енгл. Internet Protocol Security)

ARP (енгл. Address Resolution Protocol)

RARP (енгл. Reverse Address Resolution Protocol)

IPX (енгл. Internetwork Packet Exchange)

ICMP (енгл. Internet Control Message Protocol)

CLNP (енгл. Connectionless Networking Protocol)

IGP (енгл. Interior gateway protocol)

EGP (енгл. Exterior Gateway Protocol)

IGRP (енгл. Interior Gateway Routing Protocol)

EIGRP (енгл. Enhanced Interior Gateway Routing Protocol)

IS-IS (енгл. Intermediate system to intermediate system)

OSPF (енгл. Open Shortest Path First)

RIP, RIPv2 (енгл. Routing Information Protocol)

BGP (енгл. Border Gateway Protocol)

Протоколи приступа мрежи: [уреди]


Ethernet

Token Ring (енгл. Token ring)

CDP (енгл. Cisco Discovery Protocol)

HDLC (енгл. High-Level Data Link Control)

Frame Relay (енгл. Frame Relay)

MPLS (енгл. MultiProtocol Label Switching)

PPP (енгл. Point-to-Point Protocol)

NDP (енгл. Neighbor Discovery Protocol)

STP (енгл. Spanning tree protocol)

VTP (енгл. VLAN Trunking Protocol)


ADSL (енгл. Asymmetric digital subscriber line)

ISDN (енгл. Integrated Services Digital Network)

RS-232

RS-485

EIA-422

----------------------------------------------------------------------------------------------------------

List of Network Jokes

***************************

Chuck Norris

911 is Chuck Norris’ cell phone number.

Chuck Norris doesn’t do TCP handshake – he does TCP roundhouse-kick to initiate the connection.

Chuck Norris can strangle you with a cordless phone.

Chuck Norris is able to answer missed call before it is missed.

Chuck Norris can cut cable from WiFi.

Chuck Norris doesn’t use pickup lines, he simply says, “Now.”

The world is moving from IPv4 and going straight to IPv6 because Chuck Norris doesn’t like the

number 5!

There are no hidden IOS commands. Only those Chuck Norris chooses not to look at!

Cisco implemented the “test crash” hidden IOS command because it was otherwise impossible to

break a router that Chuck Norris had worked on!

Metric in RIP represents distance between router and Chuck Norris. Lower the distance is, Chuck is

closer to punch your packet and send it to grave.

DHCP

DHCP jokes are leased.

A DHCP packet walks into a bar and asks for a beer. Bartender says: “here, but I’ll need that back in

an hour!

I’m a DHCP server at a local restaurant. This chick came up and asked me for my address, and I told

her she was out of my scope.

DNS

The best thing about DNSSEC jokes is that you can check if they were told wrong.

DNS is the root of all problems.

You know it’s love when you memorize her IP number to skip DNS overhead.

WHOIS going to tell us a Domain Name joke?

Ethernet

I had an Ethernet joke, but somebody else told it at the same time. So I exponentially backed off and

tried again.

{1,Two guys}{2,Hear about}{1,are talking}{2,the dope}{1,in}{2,who confused}{1.full-duplex,}{2,TDM

with full-duplex?}

LAN jokes can only be told properly if you tell an STP joke first.

You have to tell a broadcast joke to everybody to find the one who see the fun on it.

Broadcast your own ARP jokes, mine are only funny within the same collision domain.

ARP jokes are often gratuitous.

An ARP request goes to McDonald’s and asks for a Big MAC.

I like ARP jokes, because it’s so easy to make them appear to originate from other persons.

How do you catch an Ether bunny? With an Ethernet.

HTTP

The best thing about 404 jokes is… wait, damnit, it’s around here somewhere…

There’s no more 301 jokes because they have all been moved permanently.

HTTP 200 jokes are only OK.

IPv4

An IPv4 address walks into a bar and says: “Quick, give me a drink. I am exhausted!”

The worst thing about protocol jokes is the ridiculous TTL.

I’d tell you the one about the CIDR block, but you’re too classy.

Didn’t we run out of IPv4 jokes?

After dropping the packet the IP said it was my best effort.

RFC1918 jokes are inside jokes.

IP packet with TTL=1 arrives at bar. Bartender: “Sorry, can’t let you leave… and you don’t get any

beer either…”

Router: It hurts when IP.

Network pray: Dear Lord, Please grant me the ability to punch people in the face over standard

TCP/IP.

We need to find more space for the IPv4 Comedy Roadshow, since all seats are taken.

There’s no place like 127.0.0.1.

I have told IPv4 joke 254 times. Then it stopped being funny.

I have told IPv4 joke to my friend. He checked checksum and had best effort laugh.

I have tried to tell you IPv4 joke, but you were unreachable.

Yo mama is so used, they call her IPv4.

“Hello, here’s a packet : “The problem with low MTU jokes is you can”. Hello, here’s a packet : “wait a

long time before reading”. Hello, here’s a packet : “it.”

192.168.0.1 jokes are best told in private.

IPv6

The bad thing about IPv6 jokes is that nobody wants to tell them first.

The best part about IPv6 jokes is that you don’t have to make up the punchline for 15 years.

The great thing about Teredo jokes is that you can tell smart jokes even when surrounded by dumb

peers.

The problem with IPv6 jokes is they’re long, obscure and no one gets them without a translation.

I know a great IPv6 joke, but I just don’t think you’re ready for it.

An IPv6 packet walks into a bar. Nobody talks to him.

The great thing about Teredo jokes is that you can tell smart jokes even when surrounded by dumb

peers.

I will tell you IPv6 joke, but first I need to tell you IPv4 joke, so you get it.

If you run IPv6 then you’re a c001:d00d.

IPv4 is soon dead:beef.

Multicast

Sometimes I feel like a multicast packet. Ask 10 different people how to get somewhere and get 10

different answers.

A multicast packet walks into a bar and leaves by four different exits at the same time.

A multicast packet walks into 100 bars at one time.

Multicast jokes are good, but you can only get them if you bother to listen.

NTP

An NTP packet calls ahead to make sure the bar’s open. By the time he gets there, it’s closed.

I made an NTP joke once. The timing was perfect.

The trick of telling a good NTP joke is about the timing…

Routing

Is “smoke signal” a routable protocol?

I’d like to tell you the full joke about a BGP table but I don’t think you can remember it all.

The best thing about RIP jokes is that they’re funny 15 more times.

The strange thing about BGP jokes is that they’re borderline funny but everybody repeats them

anyway.

A LSA Type 6 packet walks into a bar and asks the bartender for a drink. The bartender ignores him.

A LSA Type 2 packet walks into a bar and asks for a beer. Bartender say’s “here, but don’t leave the

area with it.”

Q. What did the OSPF router say to the other OSPF router ?

A. Hello. Hello. Hello. Hello. Hello. Hello. Hello. Hello.

Five routers walk into a bar. Who gets the car keys? The Designated Router.

Is IS-IS = 0 ?

People who tell routing jokes always exceed their time-to-live.

My new OSPF neighbor told me all his jokes after we said hello to each other. Then he tells me the

whole database of jokes every 30 minutes.

I keep telling him all my RIP jokes, but he is passive about it.

I was asking all my neighbors for an EIGRP joke. Didn’t receive all replies, so I am stuck in active.

Son, If I fail to route jokes to this destination, I want you to be my feasible successor. You have good

distance.

I told EIGRP all my OSPF jokes. EIGRP said that they are infinite.

I would tell a BGP joke, but everyone probably already knows it.

The great thing about BGP jokes? Anyone can claim they are their own, all you can do is hope your

neighbours like them.

I just heard 300.000 BGP jokes.

I was arguing with my neighbor about who will tell great new BGP joke. I was locally more preferred

joke teller, but didn’t want to compete with his weight.

Game Lemmings is like static routing. If improperly configured, you loose Lemmings.

Security

SSH 1.33 and/or 1.5 protocol jokes are useless.

I heard a great one about IPSEC, but you wouldn’t get it — it’s an inside joke.

There are no good DH jokes because nobody agrees on the same prime.

The problem with a cryptography joke is that you need to tell a pair of them before anyone

understand what’s being said.

Why are ASAs so noisy? They don’t know how to ssh.

He said he was open to networking, but when we met up, he didn’t make a PEAP.

The great thing about HTTP Upgrade jokes is… wait, someone might be listening, come closer add I’ll

whisper.

The great thing about TLS jokes is that you can tell if it’s not original.

SNMP

The problem with SMTP jokes are, you need some good reason to came back after greylisting and tell

them again.

SNMP walks into a bar and gets unknown object identifier.

You need to tell a authorized POP3 joke before you can have a SMTP laugh.

Unfortunately you need MIB files to understand the best SNMP jokes.

My name is Bond, James Bond, SNMP agent.

TCP & UDP

The problem with UDP jokes: I don’t get half of them.

In high society, TCP is more welcome than UDP. At least it knows a proper handshake.

arrival order packet joke is critical to good a make

T he bes thin gabou tTCPfl owcontr oljokesi sthatthey knowwhento backo ff….

I was promised a three way and all I got was a TCP handshake.

A TCP packet walks in to a bar and says “I want a beer”, barman says “you want a beer?” and TCP

packet says “yes, a beer”.

A bunch of TCP packets go into a bar, until it’s overcrowded. The next day, half as many go in.

A bunch of TCP packets walk into a bar. The bartender says, “Hang on just a second, I need to close

the window.”

I’m going to keep telling you this TCP joke until you get it.

Want to hear a SYN FLOOD joke? -Want to hear a SYN FLOOD joke? -Want to hear a SYN FLOOD joke?

-Want to hear a SYN FLOOD joke? -Want to hear a SYN FLOOD joke?

When I try to send SYNs to chicks, I don’t get any ACKs. Just FINs and RSTs.

I dressed up as a UDP packet… I don’t think anyone got it, but I couldn’t tell.

Whats the worst thing about sending a joke in TCP? I’ll keep telling it slower and slower until you get

it.

A UDP packet walks into a bar without a checksum. Nobody cares.

TCP must be religious… Why? Because it all starts with a SYN….

Adam and Eve where in the Garden of Eden. Snake offered apple to Eve and that was the first SYN.

Voice

I always get jittery when making jokes in real time.

An RTP packet walks into a bar through the wrong entrance. The barman says “You’re not getting any

special treatment”.

The best thing about Delay-Tolerant Networking jokes is that everyone gets them eventually.

More Voice jokes are in this post.

Wireless

The bad thing about RTS jokes is, you must first get ready to get them told.

The bad thing about WEP jokes is that they all stink, so better don’t sniff them.

A joke about IEEE 802.15.5 is pointless if you tell it right.

Telling a lot of bluetooth jokes will reduce the bandwidth of your WiFi jokes.

I would tell you a WEP joke, but I need to collect 50,000 packets first.

I was telling joke to my house neighbor over WiFi, but someone interfered.

“The problem with 802.11 jokes is they probably go over your head.”

Other

I tweeted several IPX/SPX jokes, but they can’t reach the Internet.

A token walks into a bar. Another token can’t walk into the bar because it’s afraid of the dog.

XML jokes are well-formed

Open Traffic shaping: All packets are equal, but some are more equal than others.

CRC jokes tend to get repeated until you get them right.

Serial jokes must be told bit by bit.

An ICMP Redirect walks into a bar. Everybody moves next door.

See most people talk about the OSI model as having 7 layers but they don’t mention layer 8 where a

lot of the problems actually occur.

When I go to the doctor for a cold and congestion, I usually tell him I have a ton of BECN bits set on

the flow of my breathing through my nose.

CCIE people don’t use steering wheel in their cars. They use CLI.

CCIE people plan their trips with a route map.

My new year’s resolution is 1080p.

“I had a dream.. and there were 1’s and 0’s everywhere, and I think I saw a 2!” – Futurama

If you have experienced an ICMP joke, ping me.

We were supposed to be dressed in disguise. So I dressed as NAT.

The worst thing about broadcast storm jokes is that everyone’s already heard them a hundred times.

The great thing about QoS jokes is that you may never know how much attention you are getting.

POgledaj ovo posle:

http://sr.wikipedia.org/sr/RIP

http://sr.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B8%D1%81%D0%B0%D0%BA_%D0%B8%D0%BD

%D1%82%D0%B5%D1%80%D0%BD%D0%B5%D1%82_%D0%BF%D1%80%D0%BE%D1%82%D0%BE%

D0%BA%D0%BE%D0%BB%D0%B0

http://sr.wikipedia.org/wiki/%D0%A2%D0%B0%D0%B1%D0%B5%D0%BB%D0%B0_%D1%80%D1%83

%D1%82%D0%B8%D1%80%D0%B0%D1%9A%D0%B0

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Date post:	02-Jan-2016
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Cisco CCNA Help Document

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