Say I'm advertising a /24 of 18.0.0.0 to a peer 3 hops away, and my AS number is unique and I have no other peers. I just have a connection out to the Internet from an ISP. I peer with the remote router and advertise my network of 18.0.0.0/24 to that peer, while getting a default route from that peer to send traffic out. No problem so far.
But how does any traffic get to my network? If the remote peer receives traffic to 18.0.0.3, then sends it out using the next hop it uses to establish the BGP peering, the intermediate router between him and me will drop it, because that router has no route to get 18.0.0.3 to its destination at my network.
Does the peer advertise my router's IP as the router to receive the traffic? In that case, the BGP peering is merely for propagation? How would the cost be calculated on the 2 hops that presumably aren't in the BGP table?
Am I missing something here? If not, why would anyone ever peer with anyone that's not directly connected? Johnny Cochran says it does not. Make. Sense!
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