It is important to understand the different prompts you can find when configuring a router so you can know where you are at any time within configuration mode. In this lab, the prompts that are used on a Cisco router will be demonstrated. Always check your prompts before making any changes to a routers configuration.
1- To configure a device from the CLI, you can make global changes to the router by typing configure terminal (config t for short), which puts you in global configuration mode and changes what is known as the running-config. You can type config from the privileged mode prompt and then just press enter to take the default of terminal.
Router#config
Configuring from terminal, memory, or network [terminal]?enter
Enter configuration commands, one per line. End with CTRL/Z.
Router(config)#
At this point you make changes that affect the router as a whole, hence the term global configuration mode. Notice the prompt is now Router(config)#.
2- To make changes to an interface, you use the interface command from global configuration mode.
Router(config)#interface ?
Async =============> Async interface
BRI===============> ISDN Basic Rate Interface
BVI ===============>Bridge-Group Virtual Interface
CTunnel ===========>CTunnel interface
Dialer =============> Dialer interface
FastEthernet ========>FastEthernet IEEE 802.3
Group-Async =======>Async Group interface
Lex ===============>Lex interface
Loopback ==========>Loopback interface
MFR ===============>Multilink Frame Relay bundle interface
Multilink =========>Multilink-group interface
Null ==============>Null interface
Tunnel ============> Tunnel interface
Vif ===============>PGM Multicast Host interface
Virtual-Template ==> Virtual Template interface
Virtual-TokenRing ==>Virtual TokenRing
range ============> interface range command
Router(config)#interface fastethernet 0/0
Router(config-if)#
Notice the prompt changed to Router(config-if)# to tell you that you are in interface configuration.
3- Sub interfaces allow you to create virtual interfaces within the router. The prompt then changes to.
Router(config-subif)#.
Router(config-if)#int f0/0.?
<0-**********> FastEthernet interface number
Router(config-if)#int f0/0.1
Router(config-subif)#
Type exit to go back to global configuration mode.
Router(config-subif)#exit
Router(config)#
4- To configure user mode passwords, use the line command. The prompt then becomes Router(config-line)#.
Router#config t
Enter configuration commands, one per line. End with CTRL/Z.
Router(config)#line ?
<0-70> First Line number
aux Auxiliary line
console Primary terminal line
tty Terminal controller
vty Virtual terminal
x/y Slot/Port for Modems
Router(config)#line console 0
Router(config-line)#
The line console 0 command is known as a major, or global, command, and any command typed from the (config-line) prompt is known as a subcommand.
5- Type exit to go back to global configuration mode.
Router(config-subif)#exit
Router(config)#
6- To configure routing protocols like RIP and IGRP, use the prompt (config-router)#.
Router(config)#router rip
Router(config-router)#
It is not important that you understand what each of these commands does at this time. These will all be explained later in great detail in the standard and extended labs. What you need to understand is the different prompts available.
7. Type control+z to go back to global configuration mode.
Router(config-router)#^z
Router#
