[c-nsp] BGP to OSPF redistribution

[Tolstykh, Andrew]

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ospfshmk.
html

Using a Sham-Link to Correct OSPF Backdoor Routing

Although OSPF PE-CE connections assume that the only path between two
client sites is across the MPLS VPN backbone, backdoor paths between VPN
sites (shown in grey in Figure 2) may exist. If these sites belong to
the same OSPF area, the path over a backdoor link will always be
selected because OSPF prefers intraarea paths to interarea paths. (PE
routers advertise OSPF routes learned over the VPN backbone as interarea
paths.) For this reason, OSPF backdoor links between VPN sites must be
taken into account so that routing is performed based on policy.


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of null zeroroute
Sent: Wednesday, January 13, 2010 2:20 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] BGP to OSPF redistribution

I'm having a problem trying to figure out a way to get eBGP learned
routes
(from a layer-3 VPN MPLS WAN provider) into our internal OSPF, so that
the
routes learned via the provider are preffered over the internally
learned
OSPF routes.

No matter where the BGP-->OSPF redistribution point is, if it's the PE
or
CE, the routes will still show up (by default) as OSPF external, and
will
never be prefferred.

The provider who's path we prefer will only run BGP.  We would like to
use
OSPF everywhere if possible, for several reasons.

WAN provider A is a layer-3 VPN MPLS network, and is the prefferred
path.
WAN provider B is a layer-2 VPN MPLS network over which we run OSPF.
Provider B's network is inferior at times and we use it as a backup.

The equipment where the eBGP peering relationsips exist is a mix of
7600,
3800, 2800, 1800, 6500, 3750, 3550.

We considered GRE over the providers network however we then wind up
with
25+ tunnels at each location, and that just grows as each new site is
added,
not to mention some potential issues regarding throughput with a GRE
tunnel
in the path.

Is there a way to redistribute BGP into OSPF so that the routes can be
anything but OSPF external?

I have not found a way to do this yet, and was wondering if it's even
possible, or if I'm missing something obvious.  Any suggestions
appreciated.
_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/