[c-nsp] BGP weight

[Michael K. Smith]

Hello Scott:

Answers inline below.


On 4/19/06 2:51 PM, "Voll, Scott" <Scott.Voll at wesd.org> wrote:

> I'm already using communities to get the load balance I'm looking for on
> the inbound, but my out bound is going out the one provider and not much
> out the other.  
> 
> Most of the routes I see in my BGP table are three AS's away.  So with a
> tie (my understanding) the first peer up get's the traffic.

The last step in the algorithm relies on lowest peer IP address, so that is
the one that will be preferred if it's making it that far.
> 
> What if I want a particular network to go out one peer rather then
> another?  What should I be using?  Localpref? Weight? ??  This is a
> single BGP router with three external BGP peers.
> 
I think it depends a bit on what characteristics that network has that you
wish to match.  That is, do you want to match on source AS, CIDR block,
number of AS hops, etc.

In general, I would say you should come up with a community strategy that
makes interesting netblocks stand out from the rest, and then apply
route-maps with higher local prefs to those communities.  You could also
match using as-path access lists and relevant regular expressions, or some
combination of both.

Mike