Inferring the location points of traffic exchange between two networks

Wed Jan 13 21:14:08 UTC 2016

Le 13/01/2016 18:36, Reza Motamedi a écrit :
> 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?

Hi Reza,

A reasonably recent paper discussing AS relationships:
http://arxiv.org/abs/1106.2417.

Cheers,

mh

>
> Best Regards
> Reza Motamedi (R.M)
> Graduate Research Fellow
> Oregon Network Research Group
> Computer and Information Science
> University of Oregon