[c-nsp] Implementing Unicast RPF multi-homed network

[Justin M. Streiner]

On Sat, 24 Jan 2009, root net wrote:

> I was wondering where the best place would be to implement Unicast RPF on a
> multi-homed network with full routes / filtered routes and private peering
> interconnects with local ISPs (small businesses)?  Currently we just use
> ACLs to do drop spoofing on our upstream interfaces.  I have been doing some
> reading and it says to implement at the edge not core unless you manually
> setup the routes. I would like to place this on the outside interface of
> each router connected to our upstreams and on the interface that is
> connected to each local ISP.  The problem is we are doing asymmetric routing
> at the edge/core b/c our links are not the same size.  So how can we
> accomplish this?  I think way to overcome would be to use BGP attributes
> using weight maybe?

Use strict mode on your single-homed downstream customer interfaces and 
loose mode on your transit/peer interfaces.

jms