Configuring a Router

1
Configuring a Router

• CCNA 2 v3 Module 3

2
CLI Command Modes
User EXEC Privileged EXEC Global
Configuration Specific Modes
3
Configuring a Router

• Routers should be given a unique names as one of
  the first configuration tasks

Router(config)
hostname Tokyo
Tokyo(config) _
Passwords should be configured for vty lines, the
console and to control access to privileged EXEC
mode
Router(config)
enable secret class
Router(config)
line con 0
Router(config-line)
password cisco
login
Router(config-line)
To avoid passwords being shown in clear text in
the output from the show running-config or show
startup-config commands
Router(config)
service password-encryption
4
Show commands
Displays
Command
Displays all the statistics for all the
interfaces on the router
show interfaces
Statistics for a specific interface (serial 0/1)
show int s0/1
Displays information-specific to the interface
hardware
show controllers s0/1
Shows the time set in the router
show clock
Displays a cached list of host names and
addresses
show hosts
Displays all users who are connected to the
router
show users
Displays a history of commands that have been
entered
show history
Information about flash memory and IOS files
stored there
show flash
Information about the router and the IOS running
in RAM
show version
Displays the ARP table of the router
show arp
Global and interface specific status of Layer 3
protocols
show protocol
The saved configuration located in NVRAM
show startup-config
Displays configuration currently running in RAM
show running-config
5
Configuring Serial Interfaces

• Enter interface mode

Router(config)
interface serial 0/1

• Specify the interface address and subnet mask

Router(config-if)
ip address 192.168.1.1 255.255.255.0

• Set clock rate if a DCE cable is connected (skip
  this step if a DTE cable is connected)

Router(config-if)
clock rate 56000

• Serial interfaces require a clock signal to
  control the timing of the communications. DCE
  devices provide the clock. By default, Cisco
  routers are DTE devices but they can be
  configured as DCE devices.

• Turn on the interface

Router(config-if)
no shutdown
Router(config-if)
exit
Router(config) _
6
Changing and Saving the Configuration
Make changes in configuration mode
7
Interface Descriptions

• Interface descriptions can be used to identify
  information such as
• distant router
• a circuit number
• specific network segment

Router(config)
interface ethernet 0
Router(config-if)
description Room C379 LAN
Banner MOTD
Message-of-the-Day banner can be displayed on all
connected terminals
Router(config)
banner motd
Enter TEXT message. END with a character .
ACME Computer Network Restricted Access
Router(config)_
A login banner should be a warning not to attempt
login unless authorized.
8
Host Name Configuration

• Host name resolution associates a host name with
  an IP address. These address mappings are stored
  in a host table.
• Host names, unlike DNS names, are significant
  only on the router on which they are configured.
  A host table allows you to type either the host
  name or the IP address to Telnet or Ping to a
  remote host.

London(config) ip host London 200.200.200.200 Lon
don(config) ip host NewYork 10.0.0.1 London(confi
g) ip host Paris 192.168.1.1 London(config) ip
host Munich 172.16.0.1 London(config)
end London
show hosts
Default domain is not set Name/address lookup
uses domain services Name servers
are Host Flags Age Type Address(es) London (pe
rm, OK) IP 200.200.200.200 NewYork (perm,
OK) IP 10.0.0.1 Paris (perm,
OK) IP 192.168.1.1 Munich (perm,
OK) IP 172.16.0.1
9
Configuration Backup and Documentation

• The configuration of network devices determines
  how the the network will behave. Management of
  device configuration includes the following
  tasks
• Listing and comparing configuration files on
  running devices
• Storage of configuration files on network servers
  
• Performing software installations and upgrades
• Configuration files should be stored as backup
  files in the event of a problem. Documentation
  should be included with this offline information.

10
Copying, Editing, and Pasting Configurations

• To store the current configuration on a network
  TFTP server enter the following command

My copy running-config tftp Remote host ?
131.108.2.155 Name of configuration file to
writemy-config? My2 Write file My2 to
131.108.2.155 ? confirm y Writing My2
!!!!!!!!!!!!!!!!!!!! OK
A configuration file stored on one of the network
servers can be used to configure a router
Router copy tftp running-config Host or network
configuration file host? IP address of remote
host255.255.255.255? 10.0.0.13 Name of
configuration file Router-config ?
My2 Configure using My2 from 10.0.0.13? confirm
y Booting My2 from 10.0.0.13
!!!!!! OK-180/16000 bytes