We have above scenario where currently we have only single link with ISP ROUTER1 but soon we are planning to have second link on same BGP router but ISP side it will comes from ISP ROUTER2.
I heard its recommended to configure BGP with loopback source but i don't know how does that fit in DUAL router scenario. This is what we have currently configured in my router.
router bgp 30000
bgp log-neighbor-changes
network xx.xx.xx.xx mask 255.255.255.0
timers bgp 10 30
redistribute static route-map RTBH
neighbor 66.xx.xx.65 remote-as 10000
neighbor 66.xx.xx.65 description ***** ISP-ROUTER1 *****
neighbor 66.xx.xx.65 send-community
neighbor 66.xx.xx.65 weight 100
Best Answer
You want to configure iBGP with loopback sources because you will probably have multiple ways for traffic to get into the router, and the loopback never goes down. That means that the router can keep sending and receiving updates. Also, iBGP requires a full mesh, and an interface or link going down could break that unless you have it source from a loopback.
With eBGP it is a little different. You normally want to configure eBGP on the connecting interface so that BGP does notice when the link goes down. Also, eBGP can't use a different interface unless you configure
ebgp multihop. Your ISP may not even want you to do that because they don't want BGP updates flowing around inside its network to get to the other router. Likely, your ISP is not configuring that way, and if the interface is down on the ISP router, you couldn't get to it for updates, anyway.