Here is what I am trying to do.
We have 2 border routers that connect to AT&T and Time warner Internet. WE are using ibgp between them to shift internet traffic incase of outage. We are also running ebgp with AT&T and Time Warner for Internet routes.
I am replacing the route with upgrade hardware ( 3845) and AT&T is bring in a new circuit ( internet) to upgrade the internet POP.
I have already configured the route basic configuration. What I need to do is Migrate the BGP configuration (routes) from the old router to the new router. Now here is the Hitch. I need to do this with out any Major outage.
1. Is this possible?
2. can I configure BGP on the new router and leave it in shutdown state ?
3. and if so how?
First is a clarification: you do not need to migrate routes from the old router to the new one. You need to migrate the neighbor configuration and when the router can connect to the neighbors then it will learn the routes.
Depending on how the logistics are arranged for AT&T to bring in the new circuit, one alternative might be to bring up the new circuit while the old circuit is still functional; configure EBGP on the new router to AT&T (while the old router still has its neighbor relationship); configure IBGP between the new router and both of the old routers; let BGP stabilize and the new router learn its routes; then bring down the old AT&T router and decomission the old circuit. That should not produce any major outage. Note that if you are doing good failover to Time Warner then it should be able to carry the load while you switch AT&T without creating an outage.
If you want something in shutdown the best alternative would probably be to use the neighbor shutdown command which maintains the neighbor in the config but does not establish the neighbor relationship.