brierley ver 3.1 1 module 3 configuring a router

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Module 3Configuring a Router

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CLI Command Modes

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Basic Steps to Configure a Router

1. Configure hostname

2. Configure passwords

• Enable / enable secret

• Console (con 0)

• Virtual terminal (vty)

3. Configure interfaces

4. Configure routing protocol

5. Configure hostname table

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Configuring the Router Hostname

Router#config t

Router(config)#hostname Router_A

Router_A(config)#exit / end

Router_A#

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Password Configuration

• Passwords are set for:– privileged EXEC mode

• Enable password (not used if secret password is set)

• Enable secret password (restricts going from user to privileged)

– line passwords• console interface• VTY or virtual terminals

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Password Configuration

• Setting Passwords are set for:– privileged EXEC mode

• Enable password –Router(config)#enable password cisco

• Enable secret password –Router(config)#enable secret class

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Password Configuration

• Setting Passwords are set for:– line passwords

• console interface– Router(config)#line console 0– Router(config-line)#password cisco– Router(config-line)#login

• VTY (virtual terminals)– Router(config)#line vty 0 4– Router(config-line)#password cisco– Router(config-line)#login

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Password Configuration

• Password Encryption – The service password-encryption command

may be used to set passwords to not display in clear text when viewing running configuration.

– Router(config)#line console 0– Router(config-line)#password cisco– Router(config-line)#login

Router(config-line)#service password-encryption

– Secret password is always encrypted even when the command above is not used

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Password ConfigurationIf no password is set for virtual terminal sessions, no one can log into the router using a virtual terminal session

Can set 5 different passwords for the VTY lines

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show commands

• show interfaces – stats on the router interfaces• show controllers serial – hardware info re: serial

interfaces• show clock – Shows the wall-time clock in the router • show hosts – Displays a cached list of host names

and addresses • show users – Displays all users who are connected

to the router • show history – history of commands executed• show flash – info about flash memory and its IOS

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show commands

• show version – info about router and IOS running in RAM

• show ARP – Displays the ARP table of the router • show protocol – Displays the global and interface

specific status of each configured Layer 3 protocol • show startup-configuration – Displays the saved

configuration located in NVRAM • show running-configuration – Displays the

configuration currently in RAM

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Configuring a serial interface

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Configuring a serial interfaceRouter#config t

Router(config)#interface serial 0/0

Router(config-if)#ip address 192.10.10.1 255.255.255.0

Router(config-if)#clock rate 56000 (if DCE is connected)

Router(config-if)#no shutdown

A router is by default a DTEDTE device – If connecting one router to another one interface must define the clock – the DCE end of the cable (wire).

A router is by default administratively down, until it is brought up

The cable is the determining factor with regard to DTE or DCE not the router. One end of the cable is always a DTE and the other is always a DCE.

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Configuring a router

Both steps are used to remove an existing configuration

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Configuring an Ethernet interface

Ethernet (on a 2500)

Router#config t

Router(config)#interface ethernet 0

Router(config-if)#ip address 192.10.10.1 255.255.255.0

Router(config-if)#no shutdown

FastEthernet (on a 2600)

Router#config t

Router(config)#interface fastethernet 0/0

Router(config-if)#ip address 192.10.10.1 255.255.255.0

Router(config-if)#no shutdown

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Importance of Configuration Standards

• Helps reduce complexity• Limits unplanned downtime• Limits events that may impact network performance

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Interface Descriptions

Identifies important information as to what the interface is connected to

Belfast#config t

Belfast(config)#interface serial 0/0

Belfastconfig-if)#description WAN link to San Antonio

Belfast(config-if)#ip address 192.10.10.1 255.255.255.0

Belfast(config-if)#no shutdown

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Login Banners

• They are seen by everyone (telnet, AUX port, console port)

• Can convey message to all users• Might want to include a warning not to access the

device• Use a delimiting character before and after “ # “

Router#config t

Router(config)#banner motd # Authorized Users Only!!! #

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Host Name Resolution•A global configuration command

•Router(config)# ip host name ip addresses

•Router(config)# ip host Dallas 192.168.1.23 192.168.2.57

•Matches static name with IP address

•Might think of it as a convenience – not necessary, but convenient to use names instead of addresses

•Instead of using telnet 192.168.1.23 or ping 192.186.2.57

just use telnet name or ping name

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TFTP SERVER

• Used to save a copy of the configuration on a computer

• Router#copy running-config tftp

• Software has to be set up beforehand and running

• You will be prompted for information about IP address of tftp server and the file name

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Saving Configuration Files

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Module 3Configuring a Router

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