route-map match clause for existance of a BGP session?

Fri Sep 21 15:24:49 UTC 2001

Several people have requested that I post my findings..  The idea here was
to utilize multiple transit providers as backup paths for VPN connectivity
between remote locations by redistributing static host routes into the IGP
based on the availability of a particular peer.  Initially, the route
announcements for each location were not being advertised to us by our peers
at each other location, which made looking for the specific announcement
difficult, hence my question about looking specifically for the presence of
the session.  Correcting for this made it simple to implement a standard
route-map that looks for the announcement itself, rather than the session.

route-map VPNpath
match ip address prefix-list Site1
match ip route-source 10
set metric 50

router ospf 1
redistribute static subnets route-map VPNpath

When latency or packet loss or what-have-you are affecting a provider, but
the announcement is still present, it is simple to go to the router with the
best connectivity and tweak the metric value to prefer that path.  I know
that there are multiple other ways of achieving the same results, but I
kinda like this one. :)

Thanks again,
Tim

-----Original Message-----
From: Bulger, Tim [mailto:TBulger at ea.com]
Sent: Thursday, September 20, 2001 6:13 PM
To: 'nanog at merit.edu'
Subject: RE: route-map match clause for existance of a BGP session?

Thanks all for the replies.. I managed to find a solution that works for my
purpose.

-----Original Message-----
From: Bulger, Tim [mailto:TBulger at ea.com]
Sent: Thursday, September 20, 2001 10:25 AM
To: 'nanog at merit.edu'
Subject: route-map match clause for existance of a BGP session?

Sorry for the non-operational content, but looking for some Cisco advice.

Does anyone happen to know a trick for a route map match clause that will
only match if a BGP session is established with a given peer?  The idea
being to only redistribute a particular static route based on the
availability of the peer through which the next hop of the static would be
configured...

Thanks in advance,
Tim