BGP Routing with 2 peers

Posted on 2013-06-07
Medium Priority
Last Modified: 2013-07-19
We have a rather unique situation within our Carrier Network.

We have our edge router (RouterA) connected to Level 3 and using the entire BGP table.

We have a service that we need to move to that router that carries specific traffic from our customer network and sends it to another router(RouterB) that acts as a VPN Peer with a foreign network.

The router that acts as a VPN Peer advertises that networks it can communicate with via BGP to our Equipment. The traffic that needs to go to that router (RouterB) must go to RouterB.

If we add the BGP ASN and receive network advertisements from routerB, is there a way we can ensure that all routes that are advertised from it, are the ones used by our RouterA to send the required traffic?

Essentially, we need to make it so that the BGP Peers from RouterB are a higher priority than the BGP Routes we have in RouterA that we receive from level 3.

Does anyone have any thoughts how we might go about that within a BGP Configuration?

Question by:shanehooton
LVL 81

Expert Comment

ID: 39231041
Are you trying to isolate a speifuc server to only come in via routerB?
The difficulty is that BGP advertises blocks of IPs,
What is a connection between routers and routerB?
 You could route stuff coming in from routerA to routerB.
LVL 18

Expert Comment

by:Garry Glendown
ID: 39231049
Essentially, we need to make it so that the BGP Peers from RouterB are a higher priority than the BGP Routes we have in RouterA that we receive from level 3.

Not sure if I understand your setup correctly, but wouldn't an increased local preference for routes received from Router B solve that? Local preference supersedes AS hop count, so you should be done at that point ...

Author Comment

ID: 39231074
Our Edge router has the entire BGP Table downloaded from Level 3. However, routes are advertised from Router B to our Edge router. We need those routes to have a higher preference than the Level 3 advertisements.

ie.. any traffic on our internal side destination for networks advertized from routerB are sent to RouterB and not upstream to Level 3.

How do we go about that
LVL 22

Accepted Solution

Jody Lemoine earned 1000 total points
ID: 39231621
Make sure router B's prefixes are set to a higher local preference and that they're set to use the no-export community so that you don't advertise them out to your provider. The first will make them preferred and the second will keep them local to your AS.

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