Router Configuration

Entering Configurations

Perhaps the best way to illustrate IOS CLI navigation is by walking through a simple router configuration. The comments in the example do not attempt to explain the meaning of each individual command, but rather intend to display where configuration commands are entered within the IOS command structure. Pay particular attention to how the command prompt changes as the user navigates through the IOS CLI hierarchy. Also notice that global parameters are configured at the global configuration level (indicated by the “Router(config)#” prompt) whereas interface specific commands are entered after switching to the particular interface (indicated by the “Router(config-if)#” prompt). Global parameters and interface parameters are discussed further in the Displaying Configurations section under Router Management.
Router> enable – switches to privileged EXEC level
Router# configure terminal – switches to global configuration level
Router(config)# enable secret cisco – configures router with an enable secret (global)
Router(config)# ip route 0.0.0.0 0.0.0.0 20.2.2.3 – configures a static IP route (global)
Router(config)# interface ethernet0 – switches to configure the ethernet0 interface
Router(config-if)# ip address 10.1.1.1 255.0.0.0 – configures an IP address on ethernet0 (interface)
Router(config-if)# no shutdown – activates ethernet0 (interface)
Router(config-if)# exit – exits back to global configuration level
Router(config)# interface serial0 – switches to configure the serial0 interface
Router(config-if)# ip address 20.2.2.2 255.0.0.0 – configures an IP address on serial0 (interface)
Router(config-if)# no shutdown – activates serial0 (interface)
Router(config-if)# exit – exits back to global configuration level
Router(config)# router rip – switches to configure RIP routing engine
Router(config-router)# network 10.0.0.0 – adds network 10.0.0.0 to RIP engine (routing engine)
Router(config-router)# network 20.0.0.0 – adds network 20.0.0.0 to RIP engine (routing engine)
Router(config-router)# exit – exits back to global configuration level
Router(config)# exit – exits out of configuration level
Router# copy running-config startup-config – saves configuration into NVRAM
Router# disable – disables privileged EXEC level
Router> – indicates user is back to user EXEC level

In the above example, notice how the exit command is used to back up a level within the IOS hierarchy. For example, if in the interface configuration level (i.e. Router (config-if)# prompt), typing exit will put the user back in the global configuration level (i.e. Router (config)# prompt).

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