Hi NANOG, I am researcher at the University of Oregon and my question is rather primitive. My research background is in networked systems and Internet measurement so I know how things work in theory.
My question is about BGP and what can be inferred from the output of different "show" commands, regarding the point of traffic exchange of two networks with different ASNs. I tried going through the some samples on Juniper and Cisco documentations but I did not get my answer. Consider the following scenario; Say the point of traffic exchange between AS_a and AS_b is in San Francisco and we run "show bgp summary" and "show ip bgp <prefix>"on a BGP router of AS_a in LA. Do we see the peering between AS_a and AS_b in San Francisco using any of the two commands. If yes is there a way to infer that in fact the traffic is not exchanged locally in LA? I think there should be a flag to differentiate records showing iBGP vs eBGP. On the same note, if we issue the commands on a router other than the border router in San Fran, is there any difference in the output of show commands? Now how are things different if we actually run the commands on that gateway router in SF? Best Regards Reza Motamedi (R.M) Graduate Research Fellow Oregon Network Research Group Computer and Information Science University of Oregon