distinguishing eBGP from show ip BGP

Mark Tinka mark.tinka at seacom.mu
Wed Mar 11 19:50:04 UTC 2015


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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