loopback interface

[krishna3010]

hi

,can anyone help me int he concept of loopback interfaces. where are they used other than in ospf router ids?

what kind of trouble shooting can we do with them

[Bert Gevers]

Hello Krishna,

Loopback interfaces are being used to provide a stable address for protocols (eg. routing protocols, tunnels, ...).

Because a loopback interface is not connected to any hardware, a loopback interface is always up and the IP address therefore can always be used.

HTH,

Bert

[Luc De Ghein]

A loopback interface is a stable IP address as the link cannot go down. That's why it is used for example as an Identifier (ID) for routing protocols. More importantly, they are used in BGP/MPLS networks as a next-hop IP address for prefixes and endpoints of pseudowires. For example, in MPLS VPN networks, the loopback address of the egress PE router is the next-hop IP address of the BGP prefixes (MPLS VPN or VRF prefixes).

Regards,

Luc

[krishna3010]

thanks Ideghein

[krishna3010]

thanks bert