Cisco Routers
Description:
It will be a difficult task to imagine networks without Cisco routers and switches, they are just everywhere. That being said, here is a general overview on Cisco routers:
To Resolve:
Cisco routers have different modes and certain commands that you have to run for each mode. Here they are:
-
User mode => First mode you enter when the router boots. It’s the basic low priv mode. Output should say
Router>
or something like that. -
Privileged Mode => Typing
enable
at the user mode prompt takes you to this mode after you enter the enable password. You typedisable
to return to user mode andlogout
orexit
to leave altogether. Prompt may look likeRouter#
at this mode. -
Global Configuration Mode => You type
configure terminal
or config t for short at the privileged mode prompt. It should look likeRouter(config)#
at this prompt. -
Interface Configuration Mode => This mode allows you to enter commands for specific router interfaces. It is entered by typing
interface (interface name)
. The prompt will look likeRouter(config-if)#
-
Line Configuration Mode => This mode is used to make changes to the console, Telnet, or aux ports. You can control who can access the router via these ports as well as put passwords or a security feature called
access control lists
on them. Ex commandline console 0
will enter this mode. Ouput will look likeRouter(config-line)#
-
Router Configuration Mode => This mode is used to configure protocols. Ex:
router rip
changes the prompt toRouter (config-router)#
-
VLAN Configuration Mode => This mode is only on switches, but it’s worth mentioning here. You would type
config t
and thenvlan 10
for instance to access features of a VLAN. Routers equipped with Ethernet switch cards will use VLAN Database Configuration Mode which is similar to the switches VLAN Config Mode. You would runvlan database
and thenvlan 10
to add vlan 10 to the list. -
Configuring a router: At the most basic, type a
?
to get a list of commands for each mode. You tap the spacebar to seemore
and you typeq
or Ctrl+Z to get back to the command prompt. The prompt enables tab completion and wildcard completion as well. -
If you want to configure an interface, you can type
interface ?
after the enable and config t prompts. Most people only use FastEthernet, Serial, and Loopback so don’t be discouraged by the long list.
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