[c-nsp] Load Balancing, Part II

[Oliver Boehmer (oboehmer)]

> 
> Thanks to all who responded on my load balancing question on different
> protocols.  Now onto part II of the quiz :-)
> 
> I have two routers R1 and R2 attached to a single customer C.  The
> routers are connected via BGP with R1 and R2 as members of a
> confederation.  I would like to load balance between the path R1-C and
> R1-R2-C.
> 
> show ip bgp 1.1.1.0
> BGP routing table entry for 1.1.1.0/24, version 8665091
> Paths: (2 available, best #1, table Default-IP-Routing-Table)
> Multipath: eBGP iBGP
>   4000
>     1.2.0.1 from 1.2.0.1
>       Origin IGP, metric 0, localpref 100, valid, external, best
>   (65002) 4000
>     1.3.0.1 (metric 20) from 1.3.0.1
>       Origin IGP, metric 0, localpref 100, valid, confed-external
> 
> BGP doesn't seem to want to install both routes.  The AS length is the
> same since the confederation AS (65002) gets removed.  How can one
> determine why it won't multipath?

I'm not entirely sure if we're supposed to do multi-path in this
situation as confed paths are treated as "internal" in the comparison
(see Step 7 in http://www.cisco.com/warp/public/459/25.shtml), and eiBGP
multipath only works for vpnv4 paths.

You could try to configure the hidden command "bgp bestpath
multipath-relax as-path" (if it is available in the release you are
running) to see if it makes a difference, but I don't think it will
help.

	oli