Ca Ex S2 M02 Static Routing

CCNA – Semester 2

Chapter 2 - Static Routing

CCNA Exploration 4.0

2

Objectives

• Define the general role a router plays in networks.

• Describe the directly connected networks, different router

interfaces

• Examine directly connected networks in the routing table

and use the CDP protocol

• Describe static routes with exit interfaces

• Describe summary and default route

• Examine how packets get forwarded when using static

routes

• Identify how to manage and troubleshoot static routes

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Routers and Network

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Role of the Router

• The router is a special-purpose computer that plays a key

role in the operation of any data network. Routers are

primarily responsible for interconnecting networks by:

– Determining the best path to send packets

– Forwarding packets toward their destination

5

Introducing the topology

• Topology Lab

6

Introducing the topology

• Topology Lab

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Reference: Cisco router 1841’s Component

Product Description Quantity

CISCO1841

Modular Router w/2xFE, 2 WAN slots, 32

FL/128 DR 1

CAB-ACE Power Cord Europe 1

S184IPB-12406T Cisco 1841 IOS IP BASE W/O CRYPTO 1

WIC-2T 2-Port Serial WAN Interface Card 1

CAB-SS-V35FC

V.35 Cable, DCE Female to Smart Serial, 10

Feet 2

CAB-SS-V35MT V.35 Cable, DTE Male to Smart Serial, 10 Feet 2

MEM1800-32CF 32MB Cisco 1800 Compact Flash 1

ROUTER-SDM-CD CD for SDM software 1

CON-OSP-

CISCO1841 ONSITE 24X7X4 Modular Router w/2xF 1

8

Cable Standards

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Cable for LAN/WAN interfaces

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Examining the Connections of the Router

• Serial Connectors

– DB-60 port and Smart port: five-in-one serial port:

• EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA/TIA-530 standards

• Ethernet Connectors

– 2 types of connectors can be used: Straight through and Cross-over

Straight through used to connect:

• Switch-to-Router, Switch-to-PC, Router-to-Server, Hub-to-PC, Hub-to-Server

Cross-over used to connect:

• Switch-to-Switch, PC-to-PC, Switch-to-Hub, Hub-to-Hub, Router-to-Router

11

Router Configuration Review

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Examining Router Interfaces

• Examining Router Interfaces

– show ip route command – used to view routing table

– show interfaces command – used to show status of an interface

– show ip interface brief command – used to show a portion of the

interface information

– show running-config command – used to show configuration file

in RAM

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Configuring an Ethernet Interface

• Configuring an Ethernet interface

– By default all serial and Ethernet interfaces are down

– To enable an interface use the no shutdown command

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Configuring an Ethernet Interface

• Verifying Ethernet interface

– Show interfaces for fastEthernet 0/0 – command

used to show status of fast Ethernet port

– Show ip interface brief

– Show running-config

• Ethernet interfaces participate in ARP

15

Logging Synchronous Command

• In order to keep the unsolicited output separate from your input,

enter line configuration mode for the consoled port and add the

logging synchronous command.

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Configuring a Serial Interfaces

• Configuring a Serial interface

– Enter interface configuration mode

– Enter in the ip address and subnet mask

– Enter in the no shut down command

• Example:

– R1(config)#interface serial 0/0

– R1(config-if)#ip address 172.16.2.1 255.255.255.0

– R1(config-if)#no shutdown

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• Examining Router Interfaces

– Physically connecting a WAN Interface.

– A WAN Physical Layer connection has sides:

Data Circuit-terminating Equipment (DCE) – This

is the service provider. CSU/DSU is a DCE

device.

Data Terminal Equipment (DTE) – Typically the

router is the DTE device.

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• Configuring serial links in a lab environment

One side of a serial connection must be considered

a DCE

This requires placing a clocking signal – use the

clock rate command.

Example:

• R1(config)#interface serial 0/0

• R1(config-if)#clockrate 64000

Serial Interfaces require a clock signal to control the

timing of the communications.

• Note: Wic-2a/s support maximum clock rate is 128000 bps

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• Verifying the Serial Interface Configuration

– show interfaces command

– show ip interface brief command

– show running-config

– ping command

– show ip route

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Verifying Changes to the Routing Table

• The routing table consists of a list of "known" network addresses

- that is, those addresses that are directly connected, configured

statically, and learned dynamically.

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Verifying Changes to the Routing Table

• Observing Routes as They are Added to the Routing Table

– debug ip routing command will let us see any changes that

the router performs when adding or removing routes.

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Devices on Directly Connected Networks

• When a router only has its interfaces configured, and the routing

table contains the directly connected networks but no other

routes, only devices on those directly connected networks are

reachable.

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Devices on Directly Connected Networks

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Cisco Discovery Protocol (CDP)

Network discovery with CDP

• 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.

• 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.

• Concept of neighbors

– 2 types of neighbors

Layer 3 neighbors

Layer 2 neighbors

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Cisco Discovery Protocol (CDP)

CDP Operation

• CDP runs at the Data Link layer connecting the physical media to the

upper-layer protocols (ULPs).

• Cisco network devices, such as routers that support different Network

layer protocols (for example, IP and Novell IPX), can learn about each

other

• CDP provides the following information about each CDP neighbor

device:

– Device identifiers

– Address list

– Port identifier

– Capabilities list

– Platform

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Default Setting

Feature Default Setting

CDP global state Enabled

CDP interface state Enabled

CDP holdtime (packet holdtime in seconds) 180

CDP timer (packets sent every x seconds) 60

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Using CDP for Network Discovery

• The information gathered by the CDP protocol can be

examined with the show cdp neighbors command.

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Field Definition

Device ID The name of the neighbor device and either the

MAC address or the serial number of this

device.

Local Intrfce The protocol being used by the connectivity

media.

Holdtme The remaining amount of time (in seconds) the

current device will hold the CDP advertisement

from a sending router before discarding it.

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Capability

(Capability

Codes)

Capability (type of routing device) of the listed

neighboring device.

The capability types that can be discovered are:

R—Router

T—Transparent bridge

B—Source-routing bridge

S—Switch

H—Host

I— device is using IGMP

r—Repeater

Platform The product number of the device.

Port ID The protocol and port number of the device.

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CDP Commands

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CDP Commands

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CDP Commands

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CDP Commands

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Static Routes

with “Next Hop” Addresses

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Purpose and Command Syntax of ip route

• 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.

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Purpose and Command Syntax of ip route

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Configuring Static Routes

• Installing a Static Route in the Routing Table

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Verifying Static Route Commands

Configuring Routes to Two More Remote Networks

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Routing Table Principles and Static Routes

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Routing Table Principles and Static Routes

• Applying the Principles

42

Resolving to an Exit Interface

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Resolving to an Exit Interface

• Exit Interface is down

44

Static Routes with Exit Interface

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Configuring a Static Route with an Exit Interface

• Static routes can be configured with an exit interface, which

allows the routing table to resolve the exit interface in a single

search instead of two searches.

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Configuring a Static Route with an Exit Interface

• Static Route and an Exit Interface

47

Modifying Static Routes

• There are times when a previously configured static route needs to be

modified:

– The destination network no longer exists, and therefore the static

route should be deleted.

– There is a change in the topology, and either the intermediate

address or the exit interface has to be changed.

48

Verifying the Static Route Configuration

• Use the following commands

Step 1: show running-config

Step 2 verify static route has been entered correctly

Step 3: show ip route

Step 4 verify route was configured in routing table

Step 5 issue ping command to verify packets can reach destination

and that Return path is working

49

Static Routes with Ethernet Interfaces

• Ethernet interfaces and ARP.

– If a static route is configured on an Ethernet link, if the packet is

sent to the next-hop router then

• the destination MAC address will be the address of the next

hop’s Ethernet interface

• This is found by the router consulting the ARP table

– If an entry isn’t found then an ARP request will be sent out

50

Static Routes with Ethernet Interfaces

Static routes and Ethernet exit interfaces

• With Ethernet networks, may be many different devices sharing

the same multi-access network so the router does not know the

next-hop IP address and it cannot determine the destination

MAC address for the Ethernet frame.

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Summary and Default Static Routes

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Summary Static Routes

• Summarizing Routes to Reduce the Size of the Routing Table

• Route Summarization: Multiple static routes can be summarized into a

single static route if:

– The destination networks can be summarized into a single network

address, and

– The multiple static routes all use the same exit-interface or next-

hop IP address

53

Summary Static Routes

• Configuring a Summary Route:

Step 1: Delete the current

static route

Step 2: Configure the

summary static route

Step 3: Verify the new static

route

54

Default Static Route

• A default static route is a route that will match all packets. 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.

55

Default Static Route

• Verifying a Default Static Route

56

Managing and

Troubleshooting Static Route

57

Static Routes and Packet Forwarding

• Static Routes and Packet Forwarding

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Troubleshooting a Missing Route

• Tools that can be used to isolate routing problems include:

– ping– tests end to end connectivity

– traceroute– used to discover all of the hops (routers) along

the path between 2 points

– show IP route – used to display routing table & ascertain

forwarding process

– show ip interface brief - used to show status of router

interfaces

– show cdp neighbors detail – used to gather configuration

information about directly connected neighbors

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Solving the Missing Route

• Finding a missing or miss-configured route requires methodically using

the correct tools

– Start with ping. If ping fails then use traceroute to determine

where packets are failing to arrive

• Issue: show ip route to examine routing table.

– If there is a problem with a miss-configured static route remove the

static route then reconfigure the new static route

Solving:

– R2(config)#no ip route 172.16.3.0 255.255.255.0 serial0/0/1

– R2(config)#ip route 172.16.3.0 255.255.255.0 serial 0/0/0

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Basic Static Route Configuration Lab

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Challenge Static Route Configuration Lab

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Summary

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Date post:	18-Nov-2014
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Ca Ex S2 M02 Static Routing

Technology