[c-nsp] MPLS/VPN Loadbalancing with 2 CPE routers

[Oliver Boehmer (oboehmer)]

>
> 
>I'm trying to find a way to use both links at the same time with only one
>HSRP master on the primary router...
>
>I had 2 ideas :
>
>1/ use local pref to use one link for a specific dest network and the
>second link for another network

obviously depends on number of networks and the distribution of traffic,
most of it might only go to one destination, which wouldn't then be
load-shared.. also cumbersome, so wouldn't go down this path.

>
>2/ on the primary HSRP router, create 2 ebgp : one with the PE directly
>connected and one withe PE which is connected to the secondary router
>(ebgp
>multihop with static routes pointing to the secondary CPE) On the
>secondary
>router, use only one ebgp with the router directly connected. If the HSRP
>is going to be master on the secondary link, the traffic will be going to
>the second link only but I can tell to my customer that the loadbalacing
>is
>going to work only when the HSRP is master on the primary router..

This would work (and the caveat seems acceptable), I know of one SP who
does this with their VPN customers. just make sure you configure a weight
or localpref or something on the standby so you will never prefer an iBGP
path over eBGP, or you would run into loops.

An alternative would be eiBGP multipath on the active. I've never used
this in a global routing context (it was developed for use on MPLS-VPN
PEs), so pls try or, worst case, put the routes into a VRF on the CEs
(vrf-lite). Same recommendation wrt loop avoidance applies here as well.

Or use a GRE tunnel (shudder ;-)

	oli