Route selection for BGP

[thomuff]

Location A is connected to Location B,C,D via an MPLS network running BGP

Location A has weighted static routes( metric of 250) for Location B,C,D pointing to a VPN Concentrator for a backup VPN connection.

The static routes are winning selection over the advertised BGP routes.

Why are the statics routes winning over the BGP routes?

[luqmankondeth]

Ive never set the local-preference to redistributed routes , personally I would apply the local-prefernce to the route when learned from the ebgp neigbhor.

An interesting twist to this scenario is as follows

a) Your router boots up. You have not applied the weighted static yet.

b) the route is learned via ebgp. SInce this is the only source for the prefix , it will be installed in the routing table

c) If you apply the static now, it will not replace the ebgp learned prefix (higher admin distance) and will not be redistributed into bgp. So, your intended outcome works, ie , static kicks in only when bgp route disappears. But, once your static kicks in, the sequence of events that I narrated before will happen and your routing will break.

Just thought to share this with u....

[thomuff]

That is good to think. I wasn't even thinking about the switching back part.

[thomuff]

How would you that? Would on set it at remote location?

Location A is HQ with the static routes for VPN backup

Location B is the remote location that is the home of the network (for example,10.10.10.0/24) Would I set the local preference At location B or would I set it when it coming into Location A's router?

I understand the end result but I am not sure how to get there.

[etienne.basset]

hello

route-map setpref

set local-preference 90

set weight 0

without setting weight, localpref won't do anything since redistributed routes have by default a weight of 32768 and weight is considered before LOCAL_PREF right? ...

regards

Etienne

[luqmankondeth]

You would set it at location A. Use the route-map supplied by Etienne during redistribution.

so ure config will be

router bgp 1

redistribute static route-map setpref

or modifications of it.

[Pavel Bykov]

Why not block of redistribution of this static route completely?

Like this:

global:

ip prefix-list blockstatic seq 5 permit 10.7.7.0/24

route-map blockstatic deny 10

match ip address prefix-list blockstatic

route-map blockstatic permit 20

bgp:

redistribute static blockstatic

[luqmankondeth]

Probably because thomas wants his internal peers to learn the backup route.

[thomuff]

that is correct. My internal peers need to know the backup route.