[c-nsp] BGP next-hop, default routes and more!

[Anton Smith]

> From: "Jee Kay" <jeekay at gmail.com>
> Subject: [c-nsp] BGP next-hop, default routes and more!
> To: c-nsp <cisco-nsp at puck.nether.net>
> Message-ID:
> 	<aad9e1ca0701101225h1aeda697v5b5d16dc252bab6a at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
> 
> I am currently trying to set up the following routing for our CPE bits:
> 
> CPE--PE--Aggregation--Core
> 
> The Core device generates our aggregate routes and does BGP RR magic.
> Our Aggregation connects to said RR magic, and the CPE then connects
> to the Aggregation layer via IBGP to learn various routes. In
> addition, the CPE has a static default configured pointing at the
> remote PE interface.
> 
> So far so good..
> 
> The problem is that that the aggregation device loopback is in the
> address space covered by the aggregate routes advertised by the core.
> As far as I can tell, this leads to:

*snip*

Try running your IBGP session between the addresses on your link nets 
rather than to the loopbacks. If you don't have an alternate path to get 
to the loopback on the PE, then there is no benefit in running the 
session to it. Then you get directly connected routes which will always 
be there and they will win over any BGP learnt routes. To get this to 
work you may need to use the neighbor update-source option.

Cheers,
Anton