[c-nsp] BGP route filtering question about upstreams

[Andrew Miehs]

On Wed, Oct 8, 2014 at 12:27 AM, Andrew (Andy) Ashley <andrew.a at aware.co.th>
wrote:
>
>
> Apologies, I should have clarified here:
> AS200 operates both a domestic and an international BGP routing table.
> AS300 operates a combined BGP routing table.
> The scenario is concerned with international routing only.
> AS200 should still provide routes to AS300 and its customers via the
> domestic table.
> The idea is to avoid international paths over AS200 ending up on the AS300
> international backbone (since AS200 is also a transit customer of AS300).
>

If AS200 is running two separate routing tables, I would expect them to
have two ASes - and you would peer with either one or both of them.

If AS200 (International) is a transit customer of  AS300, and AS300 breaks
their routing, you may still end having an issue with how AS200 routes
their traffic outbound... AS200 (International) may offer you communities
that you can add to your announcements that would allow you to increase the
AS PATH between AS200 and AS300 for your networks.

So based on this, I would assume you peer with AS200, AS201 (Domestic
version of 200) and AS300. For you it would be like peering with 3
different companies.


Andrew