Router Configuration Itcn

7/27/2019 Router Configuration Itcn

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Configuring a Router

MM Clements


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Copyright 2003

www.ciscopress.com

This Week

Command line interface

Router configuration Modes for configuration

Interface configuration

Working with configurations using PacketTracer 5.x


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Conventions used in these notes

All commands e.g. enable will use Courier

font to distinguish them from text After each command has been entered you

should press Enter (Return)


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Cisco IOS

Internetwork Operating System

Accessed via command line only No GUI makes for increased OS reliability

and lower hardware requirements

Has modes for operation unlike Linux or DOS


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Command-Line Interface Modes


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Global Configuration Modes


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Initial login to a router

Power up router

System information displayed Begins in User Executive mode

Users can do little (damage!) here

Enter Privileged Executive mode withenable command

May be password protected

User will be prompted if necessary


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Router Boot Process

Router decompresses IOS image from Flash

memory Legal information is displayed

On first ever ( or clean ) boot, user is asked

whether or not to enter configuration

dialogue

This is for non-Cisco educated people

answer n ( for NO )


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System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)

Copyright (c) 2000 by cisco Systems, Inc.

cisco 2620 (MPC860) processor (revision 0x200) with 60416K/5120K bytes of

memory

Self decompressing the image :#########################################################################

# [OK]

Restricted Rights Legend

Use, duplication, or disclosure by the Government is

subject to restrictions as set forth in subparagraph

(c) of the Commercial Computer Software - Restricted

Rights clause at FAR sec. 52.227-19 and subparagraph

(c) (1) (ii) of the Rights in Technical Data and Computer

Software clause at DFARS sec. 252.227-7013.

Cisco Systems, Inc.

170 West Tasman Drive

San Jose, California 95134-1706


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Clean Boot Continued--- System Configuration Dialog ---

Continue with configuration dialog? [yes/no]: n

Press RETURN to get started!

Router>?

Exec commands:

Session number to resume

connect Open a terminal connection

disable Turn off privileged commands

disconnect Disconnect an existing network connection

enable Turn on privileged commands

Etc. etc.


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Learning the Commands

Unlike Linux and DOS, all commands

available can be accessed using a questionmark ( ? ) displays minor help too

This allows all or partially typed commands

to be shown

E.g. to show all commands that begin with

the letter c type c? at the prompt and

press enter (return)


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Getting Going

In User Exec the prompt is Router>

From User Exec proceed to Privileged Execusing the enable command

Now you are in Privileged Exec the prompt isRouter#

This mode allows many parameters of the

router to be viewed

These can be seen using a show command


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Examining the show Commands

There are many show commands that

display the settings for the router Also useful for troubleshooting

In both Privileged EXEC and User EXECmodes, the command show ? provides a list

of available show commands


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Making Changes to the Router

To change settings you need to enter Global

Configuration mode This can be achieved using the configure

terminal command

The prompt now changes to Router(config)#

A different set of commands are now available

Many configuration modes exist too


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Configuring a Router Name

A router should have a name to allow it to be

easily identified The location is a good choice but any name

can be set

Router(config)#hostname Chatham

Chatham(config)#

The routers security should be considered too


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Router Identification Configuration


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Password Configuration


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Configuring an Ethernet Interface

1. Enter global configuration mode

2. Enter interface configuration mode3. Specify the interface address and subnet

mask

4. Enable the interface


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Setting FastEthernet Interface

Router(config)#interface FastEthernet 0/0

Router(config-if)#ip address 192.168.1.1

255.255.255.0

Router(config-if)#no shutdown

%LINK-5-CHANGED: InterfaceFastEthernet0/0, changed state to up

Router(config-if)#


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What interfaces does the router have?

You need to use a show command

show ip interface brief will list allinterfaces of the router

The names of the interfaces must be entered

to make changes to the interfaces of the

router


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Router#show ip interface brief

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 unassigned YES unset administratively down down

FastEthernet0/1 unassigned YES unset administratively down down

Serial0/0 unassigned YES unset administratively down down

Serial0/1 unassigned YES unset administratively down down


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Interface Configuration Commands


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Interface Descriptions

An interface description should be used to identify

important information such as a distant router, a

circuit number, or a specific network segment.


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Adds, Moves, and Changes


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Finishing the Configuration

Once finished you should type the exit

command to return one step back in the

command mode structure

To immediately return to Priv Exec, type theendcommand

Now you need to save the configuration or ifpower is lost, the configuration is lost


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Saving the Configuration

When in Global Config mode, you are writing

directly to DRAM

The contents of DRAM can be accessed usingthe running-config file but are lost if the

power is turned off

The Priv Exec command copy running-config startup-config saves the contents

of DRAM to NVRAM for the next reboot


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Checking you have saved properly

After issuing the copy running-config

startup-config hcommand the router

displays the following

Router#copy running-config startup-config

Destination filename [startup-config]?

Building configuration...[OK]

Router#


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Rebooting the router

At Priv Exec prompt, issue the reload

command and confirm (Enter)

The router restarts but no longer displays the

same question about initial configuration

You should be able see all of the information

that you entered when in Priv Exec again

Type the show running-config

command and examine the output


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Conclusion

Cisco IOS allows command line modification

A ? allows commands to be displayed CLI has modes for configuration

Need to be in the right mode to make

changes

running-config file is the contents of DRAM

startup-config file is used to store routers

configuration for the next boot

Documents

Router Configuration Itcn