Peer Establishment - iBGP
Source address is the outgoing interface towards the destination but peering in this case is using loopback interfaces!
Force both routers to source from thecorrect interface
Use “update-source” to specify the loopback when loopback peering
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 update-source Loopback0
neighbor 3.3.3.3 remote-as 2
neighbor 3.3.3.3 update-source Loopback0