ConfiguringARouter

8/7/2019 ConfiguringARouter

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Ch.3 Configuring a Router

CCNA 1 version 3.0

Rick Graziani

Cabrillo College


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Rick Graziani [email protected] 2

Overview

Students completing this module should be able to:

Name a router Set passwords Examine show commands

Configure a serial interface Configure an Ethernet interface Execute changes to a router Save changes to a router

Configure an interface description Configure a message-of-the-day banner Configure host tables Understand the importance of backups and documentation


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CLI command modes

Router#configure terminal

Router(config)#


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Configuring a router name

Router#config t

Router(config)#hostname Tokyo

Tokyo(config)#

Mistake

Should be


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Configuring router passwords

Not recommended, clear text

Router(config)#enable secret

Use this command instead, password is encryped

Encrypts the passwordsabove, but


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WARNING

service password-encryption uses a Cisco Level 7encryption which is very easy to decrypt.

For the GetPass! software www.boson.com However, the enable secret uses a stronger

encryption method and cannot be easily hacked.

service password-encryption command


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Doesnt work for enable secret!

More later!

enable secret command


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exit

end

Using exit, endand Control-Z


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Router>ena

Router#configure terminal

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

Router(config)#?

Configure commands:

aaa Authentication, Authorization and Acc..

access-list Add an access list entry

alias Create command alias

appletalk Appletalk global configuration commands

arap Appletalk Remote Access Protocol

arp Set a static ARP entry

Router(config)#exit

00:03:20: %SYS-5-CONFIG_I: Configured from console by con

Router#

Router(config)#interface interfaceRouter(config-if)#exit

Router(config)#router routing-protocol

Router(config-router)#exit

Router(config)#exit

Router#

Message each time you exit global

configuration mode

Must be in privileged mode



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Router# conf t (abbreviated)

Router(config)# router protocol

Router(config-router)# (commands)

Router(config-router)# exit

Router(config)# exit

Router#

Router(config)# interface type port

Router(config-if)# (commands)Router(config-if)# end (or Control-Z)

Router#



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Examining the show commands

show interfaces Displays all the statistics for all the interfaces on therouter. To view the statistics for a specific interface, enter the showinterfaces command followed by the specific interface and port number.

show controllers serial Displays information-specific to the interfacehardware

show clock Shows the time set in the router show hosts Displays a cached list of host names and addresses

show users Displays all users who are connected to the router show history Displays a history of commands that have been entered show flash Displays information about flash memory and what IOS files

are stored there

show version Displays information about the router and the IOS that isrunning in RAM

show ARP Displays the ARP table of the router show protocol Displays the global and interface specific status of any

configured Layer 3 protocols

show startup-configuration Displays the saved configuration locatedin NVRAM

show running-configuration Displays the configuration currentlyrunning in RAM


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Router>show interface ethernet 0Ethernet0 is administratively down, line protocol is down , using hub 0

Hardware is Lance, address is 0010.7b3a.cf84 (bia 0010.7b3a.cf84)

MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255

Encapsulation ARPA, loopback not set, keepalive set (10 sec)

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output 01:05:35, output hang never

Last clearing of "show interface" counters never

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 input packets with dribble condition detected

63 packets output, 11676 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out

Router>

StatusMAC Address

Routing

metric

information

(later)

Data link

encapsulation

(Ethernet-II)

ARP cache entries timer

show interfaces command


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Where is the MAC Address?

Router>show interface serial 0

Serial0 is administratively down, line protocol is down

Hardware is HD64570


Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Queueing strategy: fifoOutput queue 0/40, 0 drops; input queue 0/75, 0 drops

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

28 packets output, 9576 bytes, 0 underruns

0 output errors, 0 collisions, 17 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=down DSR=down DTR=down RTS=down CTS=down

Router>


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Examining the show commands

We will log into a router a examine some of the showcommands.


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Configuring a serial interface

Router(config)#interface serial 0/0

Router(config-if)#ip address

Configuring an IP Address on an interface


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show ip interface command

A serial interface will not show up and up unless bothends are properly configured (mostly) and a the no

shutdown command is used. If one routers configuration looks okay, check the other

routers configuration.

Router# show ip interface brief

Interface IP-Address OK? Method Status Protocol

Ethernet0 131.108.1.11 YES manual up up

Serial0 198.135.2.49 YES manual administratively down down

What is wrong here? The administrator has either done a

shutdown on the interface or has forgotten to do a no shutdown.


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Lab

Real world

On serial links that are directly interconnected, as in a lab environment,one side must be considered a DCE and provide a clocking signal.

The clock is enabled and speed is specified with the clock ratecommand.

Router(config)#interface serial 0/0

Router(config-if)#clock rate 56000

Router(config-if)#no shutdown



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RouterB(config)#inter serial 1

RouterB(config-if)#clock rate ?

Speed (bits per second)

12002400

4800

9600

19200

38400

56000

64000

2000000

4000000

Choose clockrate from list above

RouterB(config-if)#clock rate 64000

RouterB(config-if)#

RouterBDCE cable

RouterADTE cable



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How can you tell which end is the DTE and which end is the DCE?

Look at the label on the cable.

Look at the connecter between the two cables - The DTE cable will

always be male and the DCE cable will always be female.

DTE Cable DCE Cable



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RouterA#show controllers serial 0

HD unit 0, idb = 0xECA4C, driver structure at 0xF1EC8

buffer size 1524 HD unit 0, V.35 DTE cable

cpb = 0x62, eda = 0x403C, cda = 0x4050

RX ring with 16 entries at 0x62400000 bd_ptr=0x4000 pak=0x0F5704 ds=0x62FFB8 status=80 pak_size=22

RouterB#show controllers serial 0

buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 64000

cpb = 0x62, eda = 0x408C, cda = 0x40A0RX ring with 16 entries at 0x624000

00 bd_ptr=0x4000 pak=0x0F2F04 ds=0x627908 status=80 pak_size=22

RouterBDCE cable

RouterADTE cable

How can you tell which end is the DTE and which end is the DCE?

Use the show controllers command!

It will also tell you the type of cable, in our labs we will be using a V.35

cable.

This is one of few commands where there must be a space between the interface type and the port.



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Please be very careful when connecting the male and femaleV.35 cables together AND when connecting the serial cable to

the router!

They only connect ONE WAY! Be sure the two ends match! Dont force it!

This end up!

(The wider end is up.)



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running-config

IOS (running)

startup-config IOS

ios (partial)Bootup program

Executing adds, moves, and changes


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Router#show startup-config

%% Non-volatile configuration memory is not present

Router#show running-config

Building configuration...

Current configuration:

!

version 12.0

service timestamps debug uptimeservice timestamps log uptime

no service password-encryption

!

hostname Router

!

ip subnet-zero

!

!interface Ethernet0

no ip address

no ip directed-broadcast

shutdown

!

interface Serial0

no ip address


shutdown

No startup-configfile in NVRAM

Default running-configfile, created in RAM



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The running-config

The configuration file contains global, process, and interface information that directly affects theoperation of the router and its interface ports.

All changes to the router are made to the running-config file and take affect immediately on therouter (with just a couple of exceptions).

IP address

Routing Protocols

Routers Name

etc.

Router#show running-config

Building configuration...Current configuration:

!

version 12.0

service timestamps debug uptime

service timestamps log uptime


!

hostname Router!

ip subnet-zero

!

interface Ethernet0

no ip address


shutdown



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startup-config

RAMrunning-config

During bootup

Changes to the router are automatically put in the running-config file. If the router loses power or reboots, everything in RAM is lost including the running-

config file.

To make sure the changes to the routers configuration remain saved, you must copythe running-config from RAM into the startup-config into NVRAM:

Router# copy running-config startup-config


copy running-config startup-config


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Router#copy running-config startup-configDestination filename [startup-config]?


Router#show startup-config

!

version 12.0

service timestamps debug uptimeservice timestamps log uptime


!

hostname Router

!

!

ip subnet-zero

!

interface Ethernet0

no ip address


shutdown

!

The startup-config file now

identical to running-config

and the router will also havethese changes if the router

reboots.



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Or

Router# copy running startup

OR

Router# copy run start

OR

Any usage of the command or parameters, so that they are still uniquely recognizable.

WARNING Using an incorrect configuration file name could overwrite the routers IOS in flash, as the router believes

you are trying to copy a blank file into flash.

Router#copy running-config start-up

**** NOTICE ****

Flash load helper v1.0

This process will accept the copy options and then terminate

the current system image to use the ROM based image for the copy.Routing functionality will not be available during that time.

If you are logged in via telnet, this connection will terminate.

Users with console access can see the results of the copy operation.

---- ******** ----

Proceed? [confirm]^C

%Copy cancelled by user request.

Router#

Incorrect file name!

Press C



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Or

Router# copy running startup

OR

Router# copy run start

OR

Any usage of the command or parameters, so that they are still uniquely recognizable.

WARNING

This is also incorrect, and will overwrite the startup-config with a blank file.

Router#copy runningconfig startup-config

Destination filename [startup-config]?

?Bad filename

Router#

Incorrect file name!

Press C



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show startup-config

show running-config

These commands can only be done in privilege mode

because they display password information.

1

Displaying the config files


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Configuring Interfaces

Router(config-if)#exit

Router(config)#interface serial 0Router(config-if)#ip add 172.16.10.1 255.255.255.0

Router(config-if)#clock rate 64000 (only if DCE)

Router(config-if)#no shutdown


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Finishing the Configuration


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Importance of configuration standards

In order to manage a network, there must be a centralizedsupport standard.

Configuration, security, performance, and other issuesmust be adequately addressed for the network to function

smoothly. Creating standards for network consistency helps reduce

network complexity, the amount of unplanned downtime,and exposure to events that may have an impact onnetwork performance.


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Interface descriptions

RouterB#show inter e 0

Serial0 is up, line protocol is up

Hardware is HD64570

Description: Engineering LAN, Bldg. 18

Internet address is 10.1.1.1/24


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Gateway(config)#inter e 0

Gateway(config-if)#description LAN interface for MarketingGateway(config-if)#end

Gateway#

Gateway#show run


!

interface Ethernet0

description LAN interface for Marketingno ip address


shutdown

Gateway#show interface ethernet 0

Ethernet0 is administratively down, line protocol is down

Hardware is Lance, address is 0000.0c34.9ebb (bia 0000.0c34.9ebb)

Description: LAN interface for Marketing


Encapsulation ARPA, loopback not set, keepalive set (10 sec)

ARP type: ARPA, ARP Timeout 04:00:00

Gateway#copy run start

Destination filename [startup-config]?


Gateway#

Dont forget this or next time router

reboots these changes will be lost!

Interface descriptions


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Configuring interface description


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Login banners and Configuring message-

of-the-day (MOTD)

Wording is not

the same, but

you get the idea.


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Router(config)#hostname Gateway

Gateway(config)#Gateway(config)#banner motd #

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

Warning!

Stay away! #

Gateway(config)#end

Gateway#exit

Press RETURN to get started.

Warning!

Stay away!

User Access Verification

Password:

Gateway#show run


!

hostname Gateway

!

!

banner motd ^C

Warning!

Stay away! ^C

Delimiter always shows as ^C

MOTD (Message Of The Day)

Prompt changes

Login banners and Configuring message-

of-the-day (MOTD)


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Host name resolution

Router#ping 172.16.32.1

Router#ping Auckland

Router# telnet 192.168.53.1

Router# telnet Beirut

Router# traceroute 192.168.89.1

Router# traceroute Capetown

The Cisco IOS software maintains a cache of host name-to-address mappingsfor use by EXEC commands.

This cache speeds up the process of converting names to addresses. Host names, unlike DNS names, are significant only on the router on which

they are configured. (DNS is also an option later)


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Host name resolution

This does not make the router a DNS (Domain Name Server). This command does not turn your router into a DNS server. This command does not effect packets entering your router to be

routed.

This only affects the IOS commands entered at the router prompt.

Multiple ip addresses can be entered in case one interface is down. It is usually a good idea to use the same list of names on all your routerconfigs.

Router(config)# ip host SantaCruz 172.16.32.1 192.168.53.1

ConfiguringMultiple IP Addresses


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Configuring host tables


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If you are not using the services of a DNS server, it is best to disable this process. DNS (Domain Name Service) is enabled by default with a server address of

255.255.255.255, which is a local broadcast.

If enabled, with no DNS server on the network, may cause a slight, but irritable

delay when making typing mistakes.

Router(config)# ip domain-lookupRouter#wreh

Translating "wreh"...domain server (255.255.255.255) (Takes a few seconds)

Translating "wreh"...domain server (255.255.255.255) (Takes a few seconds)

Router(config)# no ip domain-lookup

Router#wreh

Translating "wreh"

% Unknown command or computer name, or unable to find computer address


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Configuration backup and documentation

Configuration files should be stored as backup files in theevent of a problem.

Configuration files can be stored on a network server, on aTFTP server, or on a disk stored in a safe place.


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Copying, editing, and pasting configurations

A TFTP server will allow image and configuration uploads anddownloads over the network. The TFTP server can be another router, or it can be a host system.


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The TFTP host can be any system that has TFTP software loaded andoperating and able to receive files from the TCP/IP network.



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RAMIOS (running)

running-config startup-config IOS

copy startup-config tftp

copy tftp startup-config

copy running-config tftp

copy tftp running-config

copy flash tftpcopy tftp flash



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Troubleshooting: Be sure you can ping the TFTP server.


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When using Windows, the TFTP server software must be running. The copy can be performed from the console port or from a telnet session. The telnet session can be performed on the same computer where the TFTP

server is running (or to a different computer).

Router# copy flash tftp

TFTP Software and Servers


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TFTP software either comes free with the OS (Linux/Unix) or can bedownloaded for free.



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Just double click on the shortcut

Remember, TFTP is Trivial FTP: No authentication

No login

No choice for directory

Uses UDP and verified via a TFTP checksum (not TCP ACKs)

Cisco TFTP Server.lnk



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Summary (1/2)

The router has several modes: User EXEC mode Privileged EXEC mode Global configuration mode

Other configuration modesThe command-line interface may be used to make changes

to the configuration:

Setting the hostname

Setting passwords Configuring interfaces Modifying configurations Showing configurations


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Summary (2/2)

An understanding of the following key points should havebeen achieved:

Configuration standards are key elements in the success ofany organization maintaining an efficient network.

Interface descriptions can include important information tohelp network administrators understand and troubleshoot

their networks.

Login banners and messages-of-the-day provide userswith information upon login to the router.

Host name resolutions translate names to IP addresses toallow the router to quickly convert names to addresses.

Configuration backup and documentation is extremelyimportant to keep a network operating smoothly.

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ConfiguringARouter

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