Command Type

There are two main types of commands on Cisco devices

  • configuration commands
  • exec commands

The configuration command is a command that is added to running-config to configure the IP address and host name of the Cisco device.

You can use the exec command to check the behavior and status of your Cisco devices. ping and traceroute commands to see if they can communicate, and the show command to check the status of your Cisco devices. You can also use the debug command to check the behavior of Cisco devices in real time. However, although the debug command allows you to check the behavior of a Cisco device in detail, it places a heavy load on the device, so you must be careful when using it.

It’s pretty obvious, but it’s important to note that various commands can be classified into these two types. And in order to use the two types of commands properly, you need to understand the modes in the CLI of your Cisco device.

Types of CLI modes

The CLI on Cisco devices offers two modes, depending on the commands that can be executed.

  • EXEC mode
  • configuration mode

EXEC mode is for executing EXEC commands. Depending on the privileges of the command to be executed, there are two modes: user EXEC mode and privileged EXEC mode.

In user EXEC mode, only a limited number of exec commands, such as ping, can be executed in user EXEC mode. The show running-config command to show running-config cannot be executed in user EXEC mode. Privileged EXEC mode is the so-called administrative privileges and allows all EXEC commands to be executed.

Configuration mode is a mode for executing configuration commands. The configuration mode is further subdivided into the following modes, depending on what configuration commands you want to execute on the Cisco device.

  • global configuration mode
  • interface configuration mode
  • routing protocol configuration mode
  • Various other configuration modes

Global configuration mode is the mode in which configuration commands related to the entire Cisco device are executed. For example, commands for setting the hostname and privileged EXEC mode password are executed in global configuration mode. Global configuration mode is also the starting point for all configuration modes.

Interface configuration mode is the mode for executing configuration commands related to the interface, such as setting an IP address for the interface.

And routing protocol configuration mode is the mode for executing configuration commands related to routing protocols such as RIP, OSPF, and EIGRP.

Figure CLI mode types
Figure CLI mode types

Navigating the CLI mode

When you connect the console to a Cisco device and launch the terminal software, the first thing you see is the following

Router con0 is now available





Press RETURN to get started.

Press the [Enter] key to log in, initially in user EXEC mode. In user EXEC mode, you will see a “>” at the prompt waiting for a command.

Router>

To go from user EXEC mode to privileged EXEC mode, type “enable”.

Router>enable
Router#

You will see a “#” at the prompt, indicating that you are in privileged EXEC mode.

Then type “configure terminal” to go from privileged EXEC mode to global configuration mode.

The prompt will read “(config)#”, indicating that you have entered global configuration mode. You will also see the message “Enter configuration commands, one per line. End with CNTL/Z.”.

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#

To go from global configuration mode to interface configuration mode, type “interface “. As an example, to go to interface configuration mode for an interface named FastEthernet0/0, this would look like this

Router(config)#interface FastEthernet0/0
Router(config-if)#

From the “(config-if)#” prompt, you can see that we are entering interface configuration mode.

You can also type “router < routing-protocol >” to go from global configuration mode to routing protocol configuration mode.When you move into RIP routing protocol configuration mode, type “router rip”.

Router(config)#router rip
Router(config-router)#

The prompt “(config-router)#” tells you that you are in routing protocol configuration mode.

Entering “exit” from interface configuration mode or routing protocol configuration mode will return you to global configuration mode. Alternatively, you can type “end” to return to privileged EXEC mode.

Router(config)#interface FastEthernet0/0
Router(config-if)#exit
Router(config)#

Router(config)#router rip
Router(config-router)#end
Router#

The following diagram summarizes the transition to CLI mode.

Figure CLI mode
Figure CLI mode

CLI modes are the basis for dealing with Cisco devices. Make sure you understand the meaning and transition of each CLI mode.

Note that it is not necessary to go back to global configuration mode to migrate to configuration mode. For example, you can go directly from interface configuration mode to routing protocol configuration mode as follows

R1(config)#interface FastEthernet0/0
R1(config-if)#router rip
R1(config-router)#

Cisco Basic