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CCNA 2 v3.1 Module 3

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CCNA 2

Module 3

Configuring a Router

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Overview

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• To go back a level

Type exit

• To return to privileged EXEC mode

Press Ctrl-Z

• To execute a command

Press Enter/Return

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Configuring a Router Name

• You must be at Global configuration mode

• Commands

Enter Privilaged exec mode

Router>enable

Enter global configuration mode

Router#Configure terminal

Enter hostname

Router(config)#hostname Tokyo

Return to configuration mode

Tokyo(config)# exit

Tokyo#

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Configuring router passwords

• Passwords ensure that only authorized users may make changes to the configuration file

• Passwords restrict access to routers through

virtual terminal lines (telnet connection)

console line

to privileged EXEC mode

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• Console Password

Enter console line

Router(config)#line console 0

Enter the password

Router(config-line)#password <password>

Force password to be activated at login

Router(config-line)#login

• Telnet Password

Router(config)#line vty 0 4Router(config-line)#password <password>Router(config-line)#login

Cisco Routers support 5 lines (0 – 4)

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To restrict access to Privileged EXEC mode

Enable password

Only used when enable secret not set

Not encrypted

Router(config)#enable password <password>

Enable secret password

Takes precedence over enable password

Encrypted

Router(config)#enable secret <password>

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Encrypting Configuration File Passwords

• To prevent passwords shown in clear text

• To encrypt passwords in configuration output that maybe exposed by “Show” command

Router(config)#service password-encryption

This uses an encryption algorithm called MD5

Note: not needed if you use “enable secret”.

• To turn this option off

Router(config)#no service password-encryption

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Show commands• To display all show commands

Router# Show ?

• Router#show interfaces

Displays statistics for all router interfaces

• Router#show interfaces serial 0/1

Displays statistics for serial 0/1 interface only

• Router#show controllers serial

Displays information-specific to the interface hardware

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Router#show clock

Shows the time set in the router

Router#show hosts

Displays a cached list of host names and addresses

Router#show users

Displays all users who are connected to the router

Router#show history

Displays a history of commands that were entered

Router#show flash

Displays information about flash memory

Displays what IOS files are stored there

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Router#show version

Displays information about the router

Displays the IOS that is running in RAM

Router#show ARP

– Displays the ARP table of the router

Router#show protocol

Displays status of any configured Layer 3 protocols

Router#show startup-configuration

Displays the saved configuration in NVRAM

Router#show running-configuration

Displays the configuration currently running in RAM

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Configuring Serial and Ethernet Ports

• Both can be configured from

Console port

Through a virtual terminal line (telnet)

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Configuring a Serial interface 1. Enter global configuration mode

Router#config t

2. Enter interface mode

Router(config)#int s0/0

3. Specify the interface ip address and subnet mask

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

4. If DCE cable set clock rate and bandwidth (not DTE)

Router(config-if)#clock rate 56000

Router(config-if)#bandwidth 64

5. Turn on the interface

Router(config-if)#no shutdown

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Configuring an Ethernet Interface

1. Enter global configuration mode

Router# configure terminal

2. Enter interface configuration mode

Router(config)#interface fast ethernet 0/0

3. Specify the interface address and subnet mask

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

4. Enable the interface

Router(config-if)#no shutdown

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Saving Configuration Changes• Save changes from RAM to NVRAM

Router#copy running-config startup-config

• Save changes from RAM to TFTP server

Router#copy running-config tftp

Examining Configuration Files

• Examine running configuration in RAM

Router#show running-config

• Examine startup configuration in NVRAM

Router#show start

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To Make Changes

• Use the word NO

• To turn off the ip address and subnet mask

Router(config-if)#no ip address

• To turn off the bandwidth

Router(config-if)#no bandwitdh

• To turn off the clock rate

Router(config-if)#no clockrate

• When changes are made

Router(config-if)#no shut

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• To turn on or enable an interface

Router(config-if)#no shutdown

• To turn off or disable an interface

Router(config-if)#shutdown

• Copy from RAM to TFTP server

Router#copy running-config tftp

• Restore from TFTP to RAM

Router#copy tftp running-config

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• Force router to use the original configuration file in NVRAM

Router#copy startup-config running-config

• Force router to use the configuration file on the tftp server

Router#copy tftp running-config

• Erase the startup configuration file from NVRAM

Router#write erase OR -Router#erase start

Router#reload -Router#reload

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Execute adds, moves, changes

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Interface Descriptions • Description is a comment about the interface

• The description may include

Purpose of the interface

Location of the interface

Devices or locations connected to the interface

• How to set up the interface description

Enter global configuration mode

Router#configure terminal

Enter the specific interface you wish to describe

Router(config)#int e0

Specify description

Router(config-if)#description Itsligo LAN, RM D2001

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Login Banners

• Displayed at login

• Conveying messages that affect all network users

E.g., Notices of impending system shutdowns.

• How to set up a login banner

Enter global configuration mode

Router#configure terminal

Enter the login banner

Router(config)#banner motd # message #

Save/backup changes to NVRAM

Router(config)#exit

Router#copy run start

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Host name resolution

• Associate a host name with an IP address

• Host Table

list of host names and associated IP addresses

• Host names are only significant on the router on which they are configured

• Steps to configure host names

Router(config)#ip host Lab_A 172.51.1.1

Router(config)#ip host Lab_B 180.101.21.1

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• To view all hosts

Router#show hosts

• To ping a host

Router#ping Lab_A

OR Router#ping 172.51.1.1

• To telnet into a host

Router#telnet Lab_A

OR Router#telent 172.51.1.1

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Configuration Backup and Documentation

• Management of device configuration includes

Listing and comparing configuration files on running devices

Storage of configuration files on network servers

Performing software installations and upgrades

• Configuration files can be stored on a

Network server

TFTP server

Disk stored in a safe place