[c-nsp] Multihomed PE-CE toplogies

[Bruce Pinsky]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Novice wrote:
> Hi Guys,
> 
> We have a large service Provder (a big Cisco shop) who is trying to do
> Multihoming of CE to 2 different SP. Wanted to know of any issues and are
> there any most commonly recommended Dual homed toplogies which others have
> tried.
> 
> Are there any good doc referring to issues and known gotchas. Customer is
> asking what are the options available ?
> 

I know of a couple of customers who are doing this.  As Scott suggested in
his reply, you should really be running BGP.

The biggest issue that I've seen so far is when one of the service
provider's control plane gets out of sync from the forwarding plane but it
fails to withdraw routes.  In that case, you continue to forward traffic
towards the faulty service provider (blackhole) and don't end up utilizing
the secondary service provider.

Solutions I've seen to that so far include tunneling across the providers
cloud or utilizing multi-hop BGP sessions across the cloud to provide a
triggering mechanism for installing the provider routes into the routing
table.  In either case, it kind of defeats the whole "any to any" concept
of L3VPN since it adds the complexity of managing the full mesh back onto
the customer. That being the case, I'd be looking for L2VPN services from
each provider as a straight replacement for leased line/frame relay and
managing my own routing infrastructure.

- --
=========
bep

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.2.2 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFEMsKIE1XcgMgrtyYRAu9VAKC/dhTw6Uu9QP60yUx42m7oRH3+KACfS5zA
P2ZaLAy9KhWP8Oo/pQ4w11k=
=Q+XI
-----END PGP SIGNATURE-----