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
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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 4
Router(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
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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
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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
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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
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Login Banners
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Displayed at login
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Conveying messages that affect all network users
E.g., Notices of impending system shutdowns.
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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
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