How to Enable and Administratively Shutdown a Cisco Router Interface

Enabling and Disabling cisco router interfaces

As a network administrator it is an everyday task to enable certain router interfaces and disable other for security measures, troubleshooting or testing network connectivity. In this quick tutorial i will show you the commands for enabling Cisco router interface and the command for administratively shutting down an interface of Cisco router.

Enabling a Cisco Router Interface:

You might be asking this question “why we need to enable an interface it should be working right after proper configuration”, but the fact is that Cisco devices  does not automatically enable any interface unless they are given the command by network administrator. So by default all the network interfaces of a Cisco router are administratively down, when an interface is properly configured it should be enabled in order to perform its function.

Command for Enabling Cisco Router Interface:

As it’s an interface configuration command therefore you should be in the interface configuration mode of that specific interface which you want to enable.

UpaaeRouter1# configure terminal       // if you are in enable mode go to global configuration mode

UpaaeRouter1(config)# interface serial  0/0  // we are enabling serial interface 0 in module 0.

UpaaeRouter1(config-if)# no shutdown

upaaeRouter1(config-if)# end

Validate if a Router Interface is Enabled:

UpaaeRouter1 #  show ip interface brief

How to Administratively Shutdown an Interface:

By default all the interfaces of a cisco devices are in administratively shutdown state, even after configuring an interface it needs enabling. Administratively shutting down an interface is very useful command and it comes in handy when a network administrator want to remove a specific route from the routing table but keep all the configuration unaltered. Sometime for security reasons it is needed to disable sending and receiving data through a certain interface which is achieved by administratively shutting down that specific interface and saves us from all the trouble of removing cables etc.

Command for Administratively Shutting Down Router Interface:

For executing this command you need to be in interface configuration mode.

UpaaeRouter1# configure terminal                // go to global configuration mode from enable mode

UpaaeRouter1(config)# interface serial 0/0  // we want to shutdown serial interface 0 in module 0

UpaaeRouter1(config-if)#  shutdown

UpaaeRouter1(config-if)# end

Validate if Serial 0/0 interface  is in Shut Down State:

UpaaeRouter1# show ip interface brief

UpaaeRouter1# show interface serial  0/0    // this command will show you the details of serial 0/0 interface
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