distinguishing eBGP from show ip BGP

Reza Motamedi motamedi at cs.uoregon.edu
Wed Mar 11 20:27:22 UTC 2015


Thanks again, Mark.

So I guess the short answer is that I can't infer anything about the
location of physical connectivity having this level of information from the
control plane. Is that a fair statement? What if the "Next Hop" is inside
the neighbor AS. I know it is a rather odd and uncommon case, but can it
help?

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

On Wed, Mar 11, 2015 at 3:50 PM, Mark Tinka <mark.tinka at seacom.mu> wrote:

>
>
> On 11/Mar/15 21:42, Reza Motamedi wrote:
>
> What I ultimately want to determine, is the location of the AS connection.
> I know for example the router is in, say LA. If hot potato lets me to send
> the packet to the neighbor AS then they have an AS connection in LA, right?
>
>  Going back to my example does the fact that the entry does not have 'i'
> mean that I can send it to AS2828 on the next hop.
>
>
> Yes - the route was not learned via iBGP; which means it was learned via
> eBGP.
>
> But that is just routing. It does not necessarily paint the forwarding
> topology (remember, routing and forwarding are two different operations).
>
> The next-hop may be local to "this router", but it could also be a tunnel
> (which may be cold-potato forwarded before exiting the local AS), or the
> eBGP session could be eBGP Multi-Hop.
>
> Mark.
>


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