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loopback address

Hi, im just a novice, what is the real essence of loopback address in a router?



Re: loopback address

Loopback is a virtual interface useful for testing, and, for some routing protocols, an anchor address and / or used in the selection of the router's place in the network hierarchy.

Since loopbacks down fail / go down (i.e., tend to be more stable than real interfaces), you can use them as the the primary identifier for that router / device.

In lab scenarios, you can can add a bunch of loopbacks and use them as a source to increase the number of routes generated.



Community Member

Re: loopback address

Loopback interface can be used for nat on stick (trying nat with only one physical interface).


Re: loopback address

Dear Revilo,

By default most of routing protocols and label protocols that used to exchange L3 information need to identify each other and it's selecet the highest address number that assigned to any interface and if there is a loopback address it's used it because the loopback interface is most stabel interface that can not down (Manualy only) by general meaning it's the router ID

Please rate helful posts

Best Regards,

Mounir Mohamed

Community Member

Re: loopback address


To have a redundancy for Primary to Backup interface. Better the VPN Tunnel should be created by loopback ip. So in case of any failure of interface the tunnel source & destination can be learnt from the live link..bcoz loopback will not go down.



Community Member

Re: loopback address


A loopback is a virtual interface which never goes down.And if you have redundant paths to router and that router is advertising its Loopback ip with the help of routing protocol configured.

Incase one of your link fails , that physical interface will go down but LOOPBACK is sill up and reachable via another path hence your router is reachable.

Loopback ip becomes router id in an ospf network or u can say becomes the identification of an ospf router.

Please rate and revert if any further confusion

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