about interdomain multipath routing.

Steven King sking at kingrst.com
Tue Nov 10 19:13:46 UTC 2009

We use multipath setups for our EIGRP and iBGP configurations for our
internal routing as well. Although for larger networks iBGP multipath
might be of use due to memory limitations on a lot of devices.

Doug Lane wrote:
> 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

Steve King

Network Engineer - Liquid Web, Inc.
Cisco Certified Network Associate
CompTIA Linux+ Certified Professional
CompTIA A+ Certified Professional

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