Internal BGP (Border Gateway Protocol) explained

Hello Xinran

Yes, that is typically the case. eBGP is primarily designed to have the routers physically directly connected to each other. That way, ASes are directly connected to each other. If you try to create an eBGP peering between two eBGP routers with multiple intermediary routers in between, by default, such a peering will fail. eBGP messages are sent with a TTL of 1, so no eBGP peering can be created with multiple hops in between.

However, you can override this default behavior with the eBGP multihop feature. You can find out more about that here:

I hope this has been helpful!

Laz