about interdomain multipath routing.

Doug Lane laned1 at gmail.com
Tue Nov 10 03:10:59 CST 2009


On Tue, Nov 10, 2009 at 3:50 AM, Matthew Petach <mpetach at netflight.com> wrote:
> I've outlawed the use of multihop eBGP for load-sharing here; when we get
> multiple links off the same router to a peer or upstream, they are configured
> with multipath.  We've got hundreds of BGP sessions across the network
> configured with multipath on them.
>

Do you use iBGP multipath as well to load-balance between links on
different routers?

I know eBGP multipath is fairly common, but I wonder how many are
using iBGP multipath as well. I doubt any carriers would support it,
so it's probably only useful for load-balancing outbound traffic. The
problem with eBGP multipath alone is that you might want to terminate
circuits from a given carrier on two different routers for redundancy
reasons, but that precludes any load-balancing with eBGP multipath.
Obviously your network has to be designed with equal-cost paths for
iBGP multipath to be of any value.

-Doug




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