Cisco Systems How to Configure Loopback Interface on Cisco Router: A Comprehensive Guide

Chapter 4 Configuring with the Command-Line Interface

Configuring Loopback Interfaces

Step 3 Change the name of the router to a meaningful name.

Router(config)# hostname router_name

The prompt changes from “Router” to the user-configured hostname once this command is issued.

Step 4 Enter an enable secret password. This password provides access to privileged EXEC mode. When a user types enable at the EXEC prompt (Router> ), they must enter the enable secret password to access configuration mode.

router_name(config)# enable secret password

Step 5 Enter line configuration mode to configure the console port. The prompt changes to

Router(config-line)#.

router_name(config)# line con 0

Step 6 Enter a timeout value of 0 to prevent the router’s EXEC facility from timing out if you do not type any information on the console screen for an extended period.

router_name(config-line)# exec-timeout 0 0

Step 7 Exit to global configuration mode.

router_name(config-line)# exit

Configuring Loopback Interfaces

The loopback interface is a software-only, virtual interface that emulates an interface that is always up. The interface-number is the number of the loopback interface that you want to create or configure. There is no limit on the number of loopback interfaces you can create.

The multilink interface is a virtual interface, if you are not going to assign an explicit IP address to the interface, you should create a loopback interface for the multilink interface to enable IP processing on the interface.

In the case where the MWR 1900 is used in a redundant configuration, you must also configure loopback interfaces for the health and revertive interfaces. The health interface monitors the status of the redundant configuration so that the standby router can take over if there is a problem with the active router. The revertive interface is required to ensure that the switchover takes place. We recommend that you use 101 for the health interface and 102 for the revertive interface.

To configure a loopback interface, do the following beginning in global configuration mode:

Step 1 Create a loopback interface for each multilink interface:

Router(config)# interface loopback number

Router(config-if)#ip address ip_address subnet_mask

Note For the health and revertive interfaces, you do not need to assign an IP address.

Step 2 Exit interface configuration mode:

Router(config-if)# exit

Cisco MWR 1900 Mobile Wireless Edge Router Software Configuration Guide

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