BGP & default route/s

[louis0001]

Hi,

we have a network with 50 sites all connected via a private MPLS network using BGP.

Our egress to the internet is at one site (SITE A) and we advertise network 0.0.0.0 here.

All is well and all sites can access the internet via SITE A.

We now have another egress point at SITE B.

What would happen if we advertise 0.0.0.0 at SITE B?

Is there a way for us to prefer SITE A 0.0.0.0 (via weights?) to SITE B 0.0.0.0 so that SITE B is only used if SITE A is offline?

[Richard Burts]

This link has an example which I hope you will find helpful.

The steps are basically these

- configure a prefix list which identifies the default route.

- configure a route map and in that route map match the prefix list to identify the default route and use the set command to prepend your AS number several times

- under router bgp assign the route map to the ISP neighbor for outbound advertisements

https://community.cisco.com/t5/routing/bgp-route-map-prepend-configuration-examples/td-p/1315239

The link gets into an extended discussion but the example comes at the beginning and is the part that you really need.

HTH

Rick