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CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY

Chabot CollegeChabot College

ELEC 99.08ELEC 99.08IOS Configuration Commands


Configuration TopicsConfiguration Topics• Configuration file• Ways to enter a config file to the router• IOS configuration commands• Additive editing


Configuration FileConfiguration File• Just a text file• Text instructions are interpreted by the EXEC.• Loaded to RAM• Changes in the config file take place

instantaneously. No reboot or other process is required.


Configuration FileConfiguration File• Commands may be entered in any order; the

IOS will place the commands in the correct position in the config file.

• Editing is additive. More about this later...


Config may be entered fromConfig may be entered from• NVRAM This is the default at reload or cold start. Also:

– rtr#config memory

– rtr#copy start run

• Setup Mode dialog– rtr#setup

• TFTP server– rtr#config network

– rtr#copy tftp run

• Terminal (con0, aux0, vty0 4)– rtr#config terminal


Review: Which mode is this?Review: Which mode is this?

• oak(config)#• Global configuration mode

Used for:– General configuration commands– Static routes



• oak(config-if)#• Interface configuration mode

Used for:– Setting IP addresses and subnet masks– Setting other interface characteristics



• oak(config-router)#• Router configuration mode

Used for:– Setting routing protocols



• oak(config-line)#• Line configuration mode

Used for:– Setting login passwords on lines:

• con 0• aux 0• vty 0 4


Global, Interface, Line & Router ModesGlobal, Interface, Line & Router Modes


Global Config CommandsGlobal Config Commands• hostname

– name of router– format: one word, no spaces– changes instantaneously

rtr#conf trtr(config)#hostname oakoak(config)#banner motd $Router Admin: J. Jones$oak(config)#ip route 0.0.0.0 0.0.0.0 s1oak(config)#enable password cisco oak(config)#enable secret chabot


Global Config CommandsGlobal Config Commands• banner motd

– message of the day (shown at login)– format: repeated character delimits message– in example below, $ is delimiter



Global Config CommandsGlobal Config Commands• ip route

– defines a “static” route– format: ip route x.x.x.x (address) y.y.y.y (mask) interface – in example below, the “default route” is set



Global Config CommandsGlobal Config Commands• enable passwword

– sets the weak “enable” password– format: enable password [word]



Global Config CommandsGlobal Config Commands• enable secret

– sets the encrypted “enable secret” password– format: enable secret [word]

– once entered, will not be readable in config file



Global Config CommandsGlobal Config Commands• no ip domain-lookup

– turns off DNS lookups– format: no ip domain lookup

– useful in lab, where there is no DNS

rtr#conf trtr(config)#hostname oakoak(config)#banner motd $Router Admin: J. Jones$oak(config)#ip route 0.0.0.0 0.0.0.0 s1oak(config)#enable password cisco oak(config)#enable secret chabotoak(config)#no ip domain-lookup


Global Config - PracticeGlobal Config - Practice• Try it now with Router e-Sim:• Enter global config mode.• Enter the following commands:

• then log in again, and note the motd and passwords

router>enrouter#conf trouter(config)#hostname haywardhayward(config)#banner motd $Administered by(yourname)$hayward(config)#enable password cisco hayward(config)#enable secret chabothayward(config)#exithayward#exit


Global config: changing to Interface ConfigGlobal config: changing to Interface Config• interface ethernet 0

– selects the interface to be configured– format: int e0 (substitute s0, s1, or e1 as appropriate)

– prompt gives no indication of the current interface being configured.

oak#conf toak(config)#int e0oak(config-if)#


Interface Config CommandsInterface Config Commands• ip address

– sets ip address & subnet mask– format: ip address x.x.x.x (address) y.y.y.y (mask)

oak#conf toak(config)#int e0oak(config-if)#ip address 192.168.4.1 255.255.255.0oak(config-if)#


Interface Config CommandsInterface Config Commands• descripton

– comment to describe the interface– format: desc [text text text]

oak#conf toak(config)#int e0oak(config-if)#ip address 192.168.4.1 255.255.255.0oak(config-if)#desc Oakland LANoak(config-if)#


Interface Config CommandsInterface Config Commands• no shutdown

– brings up an interface that was administratively shut down– format: no shut

oak#conf toak(config)#int e0oak(config-if)#ip address 192.168.4.1 255.255.255.0oak(config-if)#desc Oakland LANoak(config-if)#no shutoak(config-if)#


Interface Config CommandsInterface Config Commands• exit

– returns to Global Config mode– format: exit

oak#conf toak(config)#int e0oak(config-if)#ip address 192.168.4.1 255.255.255.0oak(config-if)#desc Oakland LANoak(config-if)#no shutoak(config-if)#exitoak(config)#


Interface Config - PracticeInterface Config - Practice• Try it now with Router e-Sim:• show interface e0 and note:

– is the interface UP and UP?– is an IP address shown?

• Enter interface config mode for Ethernet 0.• Enter the following commands:

• then show int e0 and note the effects of your configuration

hayward(config)#int eohayward(config-if)#ip address 192.168.3.1 255.255.255.0 hayward(config-if)#desc This is the Hayward LANhayward(config-if)#no shuthayward(config)#exithayward#exit


Global config: changing to Line ConfigGlobal config: changing to Line Config• line con 0

– selects the line to be configured– format: line vty 0 4 (substitute con 0 or aux 0 as appropriate)

– prompt gives no indication of the current line being configured.

oak#conf toak(config)#line con 0oak(config-line)#


Line Config CommandsLine Config Commands• login

– enables password control for login– format: login

oak#conf toak(config)#line con 0oak(config-line)loginoak(config-line)#


Line Config CommandsLine Config Commands• password

– defines the password for this line– format: password [word]

oak#conf toak(config)#line con 0oak(config-line)loginoak(config-line)#password ciscooak(config-line)#


Line Config CommandsLine Config Commands• exit


oak#conf toak(config)#line con 0oak(config-line)loginoak(config-line)#password ciscooak(config-line)#exitoak(config)#


Line Config - PracticeLine Config - Practice• Try it now with Router e-Sim:• show run and note whether there are passwords on line con 0, aux 0,

and vty 0• Enter line config mode for con 0.• Enter the following commands:

• then show run and note the effects of your configuration

hayward(config)#line con 0hayward(config-line)#loginhayward(config-line)#password ciscohayward(config-line)#line vty 0 4hayward(config-line)#loginhayward(config-line)#password ciscohayward(config-line)#exithayward#^Z

Notice thechangehere


Additional Line Config CommandAdditional Line Config Command• logging synchronous

– prevents system messages from interrupting your typing input in the middle of a line

– add to console line

– format: logging synchronous

oak#conf toak(config)#line con 0oak(config-line)logging synchronousoak(config-line)#


Additional Line Config CommandAdditional Line Config Command• logging synchronous

– Router e-Sim doesn’t understand this command, so you can’t practice with it.

– Useful in in your real config files.

oak#conf toak(config)#line con 0oak(config-line)loginoak(config-line)#password ciscooak(config-line)logging synchronousoak(config-line)#


Global config: changing to Router ConfigGlobal config: changing to Router Config• router rip

– selects the dynamic routing protocol– format: router [protocol] (rip or igrp as appropriate)

oak#conf toak(config)#router ripoak(config-router)#


Router Config CommandsRouter Config Commands• network

– sets the networks on which the protocol will send and receive updates– format: network x.x.x.x

oak#conf toak(config)#router ripoak(config-router)#network 192.168.4.0oak(config-router)#network 10.0.0.0oak(config-router)#


Router Config CommandsRouter Config Commands• exit


oak#conf toak(config)#router ripoak(config-router)#network 192.168.4.0oak(config-router)#network 10.0.0.0oak(config-router)#exitoak(config)#


Router Config - PracticeRouter Config - Practice• Try it now with Router e-Sim:• show run and note whether RIP has been set as the dynamic routing

protocol• Enter line router config mode• Enter the following commands:

• then show run and note the effects of your configuration

hayward(config)#router riphayward(config-router)#network 10.0.0.0hayward(config-router)#network 192.168.3.0hayward(config-router)#exithayward(config)#exithayward#exit


““No” CommandsNo” Commands• To remove or reverse any command, type the command

again, preceded by no

oak#conf toak(config)#no router ripoak(config)#


““No” Command - PracticeNo” Command - Practice• Try it now with Router e-Sim:• show run and note whether RIP has been set as the dynamic routing

protocol• Enter global config mode• Enter the following commands:

• then show run and note whether RIP has been deleted

hayward(config)#no router riphayward(config)#exithayward#sh ru


““No” Command - PracticeNo” Command - Practice

• Earlier, you set the ethernet 0 – IP address and subnet mask– description

• Now try using the no command to remove them.

hayward(config)#int e0hayward(config-if)#no ip addresshayward(config-if)#no deschayward(config-if)#exithayward(config)#exithayward#sh ru

• Answer:


Additive EditingAdditive Editing

• New commands add to the file and replace like commands only.

• Other commands remain in the config.• Even if you load an entire config file to RAM, old

commands not included in the new config file will remain in RAM.

• Confusion and problems can result.• Principle: Start clean to be sure:

– erase start, reload


Additive Editing - Results of Loading a Config on Top of a Current ConfigAdditive Editing - Results of Loading a Config on Top of a Current Config

!hostname oakland!enable password cisco !!!ip route 0.0.0.0 0.0.0.0 s1!no router rip

!hostname hayward!enable password cisco !banner motd $Shutdown 4PM$!!!router rip

!

1. CurrentRunning Config

in RAM

2. New Config Loaded from

NVRAM or TFTP

3. ResultingRunning Config

in RAM

!hostname oakland!hostname oakland!enable password cisco

!hostname oakland!enable password cisco !banner motd $Shutdown 4PM$

!hostname oakland!enable password cisco !banner motd $Shutdown 4PM$!ip route 0.0.0.0 0.0.0.0 s1

+ =

What will be the resulting hostname?What will be the resulting enable password?Will the resulting config include a banner motd?Will the resulting config include a static ip route?

!hostname oakland!enable password cisco !banner motd $Shutdown 4PM$!ip route 0.0.0.0 0.0.0.0 s1!!

Will the resulting config include rip routing?

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