Loopback IP Address

Unanswered Question
jbrenesj Tue, 10/20/2009 - 11:16

Loopback interfaces are used for several purposes but just to mention a few:

1. As router IDs to identify a router in a routing protocol process like OSPF. The loopback address is normally used to distinguish between neighbors

2. As the loopback interface can stay up/up even when no physical connection (a cable) is plugged in, you can use it in BGP to identify the peer and to maintain the session up even if one physical connection between routers goes down, assuming there's an alternate path

Lucien Avramov Tue, 10/20/2009 - 11:24

More generally a loopback is an interface that you can reach without having to connect a network to your device.

You can test pings to a loopback to check your connectivity or routing for example.

Just to be more precise to the previous post: the loopback is NOT always the one used for router id. It depends on the ip addressing you have on the router.

osaid suliebi Sat, 10/26/2013 - 06:31

can i use loopback interface without assign ip address to it??

i want to use it for NAT on stick

osaid suliebi Sat, 10/26/2013 - 06:31

can i use loopback interface without assign ip address to it??

i want to use it for NAT on stick

Richard Burts Sat, 10/26/2013 - 07:10

You have also asked this question in a new thread that you started. Starting a new thread is much better than trying to restart a discussion from 4 years ago. I suggest that any further discussion should focus on the new thread and not on this one.

HTH

Rick

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