A basic question about loop back address

[mahesh_kv3]

iam a 3 month old network engineer,iam in the monitoring of one MPLS network,in that routers are having loop back addressess,could any tell me the conceptuals of the loop back addresses.

[karunakargupta]

Hi,

Loopback interface is logical interface in router, which is always up. If you have multiple connectivity on router, it is used by dynamic routing protocols to update the tables. It is also used for authentication.

Thanks

Karunakar

[mahesh_kv3]

as iam an un born baby in networking,everything ur telling is pretty worth,so thanx a lott boss,

mahesh

[albert.remo]

Hi!

Good Day! Yes, loopback interfaces are logical interfaces. This means that even if your physical interfaces has failed, other routers will reach this router through the loopback interface address. In MPLS, this loopback address acts as the router ID for connectivity. For other implementations, the loopback address can be used as next hops for routing. As said, this is very beneficial because the Loopback interfaces is always active unless shutdown.

Hope this helps. Please rate if found helpful.

Regards,

Albert

[mahesh_kv3]

hi

thanx a lott fer the fast response thru the window...in MPLS it will act as an router ID but in other implementations iam not that clear if iam telling frank.could u please clear me that one also

regards

Mahesh

[albert.remo]

Hi!

I would just like to add to my post that at least one physical interface should be active to be able to reach the router. As for other implementations, these are configurations other than MPLS like BGP or even static routing. You will be able to encounter this as you go through a lot of things in networking. In time you'll see the benefits of the Loopback Interface.

Regards,

Albert

[jitesh1982]

Hello Albert,

Is there a way that can down the tunnel as and when physical interface goes down.

Regards,

Jitesh

[albert.remo]

Hi Jitesh,

If my understanding on your question is correct, making the physical interface instead of the loopback interface as the source interface like in a GRE tunnel should be able to do this.

Regards,

Albert