Configuring a Router

Different Modes of Operation of Router

User mode 

•  This mode is used for basic monitoring.
• commands used in this mode are 

                -->ping

                -->telnet

                -->traceroute

Privileged mode

• we can enter into this mode by using enable command.
• This mode is used to see and save the router configuration.But we can't change the router's configuration.
• commands used in this mode are 

1.     show commands:used to see configuration

2.     copy configuration:used to save the router configuration

3.     Debug commands:used to see the routers back end processing to front end.

 Global configuration mode

• we can enter into this mode by using the command configure terminal or configure
• This mode is used to change router's configuration.
• we can set or change hostname of the router.
• we can set or change the secret password.
• we can set banners.

Line configuration mode

• In this mode we can change theconfiguration of router for specifi line.
• commands used in this mode are

-->Login 

-->Password

Interface configuration mode

• In this mode we can change the configuration related to any interface.

BASIC COMMANDS

Router>:user mode
Router>enable  this command is to to move into privilege mode
Router# privileged mode
Router #Configure-terminal: this command is used to move into global configuration mode.
Router (config)# Here we can perform the router configuration
Router (config)#hostname  HIT  this command is used to set the host name for the router as HIT
Router (config)#enable  password  HIT this command enables the password for HIT
Router (config)#enable secret  password  HIT this command enables the encryption password for HIT

Router#show ? Lists all show commands available.
Router#show interfaces Displays statistics for all interfaces.
Router#show interface serial 0/0/0 Displays statistics for a specific interface (in this case, serial 0/0/0).
Router#show ip interface brief Displays a summary of all interfaces, including status and IPaddress assigned.
Router#show controllers serial 0/0/0 Displays statistics for interface hardware. Statistics display if theclock rate is set and if the cable is DCE, DTE, or not attached.
Router#show clock Displays time set on device.
Router#show hosts Displays local host-to-IP address cache. These are the names and addresses of hosts on the network to which you can connect.
Router#show users Displays all users connected to device.
Router#show history Displays the history of commands used at this edit level.
Router#show flash Displays info about flash memory.
Router#show version Displays info about loaded software version.
Router#show arp Displays the Address Resolution Protocol (ARP) table.
Router#show protocols Displays status of configured Layer 3 protocols.
Router#show startup-config Displays the configuration saved in NVRAM.
Router#show running-config Displays the configuration currently running in RAM.
Router(config)#do show running-config Executes the privileged-level show running-config command while in global configuration mode.
Router(config)# The router remains in global configuration mode after the command has been executed.

Router(config)#interface s0/0/0 Moves to serial interface 0/0/0 configuration mode

Router(config-if)#description Link to ISP Optional descriptor of the link is locally significant

Router(config-if)#ip address 192.168.10.1 255.255.255.0 Assigns address and subnet mask to interface

 Router(config-if)#show controller(serial interface name) this is used to know the serial cable slot attached to the router is either DCE or DTE.

Router(config-if)#clock rate 64000 Assigns a clock rate over the serial interface where DCE cable is attached

Router(config-if)#no shutdown Turns interface on

Router(config)#interface fastethernet 0/0 Moves to Fast Ethernet 0/0 interface configuration mode

Router(config-if)#description this command is used to set description over any interface of a router

Router(config-if)#ip address 192.168.20.1 255.255.255.0 Assigns address and subnet mask to interface

Router(config-if)#no shutdown Turns interface on

Router(config)#banner motd # ******MESSAGE*******. #  sets the banner for the router  as that in message

Router(config)# Router(config)#banner login # ******MESSAGE*******. # sets the banner for the login as that in message

Router(config)# The router remains in global configuration mode after the command has been executed.

Router(config)#clock timezone EST –5 Sets the time zone ((Eastern standard time is

5 hours behind UTC.)

Router(config)#ip host london 192.16.1.28 this will assign the host name for the given ip address

Router(config)#no ip domain-lookup Turns off trying to automatically resolve an unrecognized command to a local host name

Router(config)# The router remains in global configuration mode after the command has been executed.

Router(config)#line console 0 Moves to line console configuration mode.

Router(config-line)#logging synchronous Turns on synchronous logging. Information items sent to the console will not interrupt the command you are typing. The command will be moved to a new line.

Router#copy running-config startup-config Saves the running configuration to local NVRAM

Router#copy running-config tftp Saves the running configuration remotely to a TFTP server

Router#erase startup-config Deletes the startup configuration file from NVRAM

Router#reload this is used to restart the router

Router(config)#shutdown this is used to down the interface or port .

Router(config)#service password-encryption this command is used to encrypt all the password of a router.the password can't be decypted agai n once it is encrypted.