BGP peering redundancy using loopbacks
It is best practice to source BGP messages from loopback interfaces. For example, look at the following topology.
By sourcing the BGP peerings from loopbacks, if any single physical link fails, the BGP peering will still remain up. So the redundancy delivered in this case is to the BGP peering itself. It is a redundancy on the control plane.
Note:
- IGP or static routing between the routers must be configured that enables traffic between routers to use both links.
- In this particular case, eBGP multihop must be configured so that the loopbacks can create BGP peerings.
- In order to achieve redundancy in the user plane as well using BGP, features such as BGP Multipath and BGP Additional Paths must be used.
Links
https://forum.networklessons.com/t/ebgp-multihop/1228/147?u=lagapides
https://networklessons.com/bgp/ebgp-multihop/
https://networklessons.com/bgp/bgp-multipath-load-sharing-ibgp-and-ebgp