[c-nsp] iBGP and route backups

[Gordon Bezzina]

Hi,

I would like to clarify a small doubt I got in my head. I have set up 2
routers each connected externally to the same ISP but over diverse links.
These routers are then in-turn directly connected with iBGP.

One connection is designated to the the primary router whilst the other the
backup route. So what I do is that the backup gets into a rout-map that sets
it local priority to low and another route maps that pre-prends my AS a
couple of times.

This worked great whilst both connections were on the same router I would
get the following result for the default route.

Output of show ip bgp vpnv4 vrf Z

   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: X:Y (default for vrf Z)
*  0.0.0.0          A.B.C.D1           75             0 15735 i
*>                  A.B.C.D2                 200      0 15735 i

With obviously A.B.C.D2 being the primary connection AND A.B.C.D1 being the
backup connection.

The problem is that when I replicate the rules and move the backup
connection to the second router the routes that the backup router is
learning are not being distributed to the primary router. That is the route
distinguisher for the default route only shows the primary connection.

Funnily enough the second router does get the default router fro the primary
(ibgp) and from the secondary (directly connected).

I have tested with another route (specific subnet) and the route _does_ get
distributed a few seconds after the outage. Is this a normal behavior of
iBGP or I have some messed up configs?

Any hints would be greatly appreciated.

Thanks/Regards
Gordon Bezzina