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Reg Loopback Interface on router

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by dubey_296

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Plz let me know why we use Loopback Interface and Loopback Ip address on Cisco Router??

5 replies

by ispnetworker

Loopback addresses are virtual addresses assigned to a network device but not associated with any specific interface. Loopback addresses allow a connection to a device as long as there is some type of connectivity to the device.

by nakul malik

A loopback interface is used to test connectivity and/or verify configuration. For example, if we configure Router A and Router B for RIP routing, but do not have our routed interfaces up yet, there is no way for us to verify that our configuration is proper. In such a case, we would configure a couple of loopback interfaces on both sides and distribute their networks using rip, thus enabling the verification of our configuration.

A loopback interface does not have a specific IP address. youmay assign it any ip address you like.

Here is how you create one:
Router(config)# int l0
Router(config-if)# ip add 172.16.1.1

Also, a loopback interface is by default in the state - up.

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