BGP and Conditional Routing

[terry-norris]

I have a branch that will have two separate circuit coming into the router (two ISPs).  The router will talk BGP over both circuits.  What I want to accomplish is to have some BGP routes advertised out one path, but not the other.  Since this is one router with one BGP AS, how can I accomlish this within the BGP configuration?

Thank you.

[blau grana]

Hello Terry,

What do you mean by "conditional routing"? Conditional based on what?

If you want just advertise specific prefixes to one neighbor and other prefixes to another neighbor, configuration is pretty simple.

Lets say that you have two BGP neighbors, neghbor isp1 via ISP1 and neighbor isp2 via ISP2. You want advertise prefix 10.0.0.0/8 to ISP1 and prefix 192.168.0.0/16 to ISP2.

ip prefix-list ISP1 permit 10.0.0.0/8

ip prefix-list ISP2 permit 192.168.0.0/16

route-map ISP1_OUT

   match ip address prefix ISP1

route-map ISP2_OUT

   match ip address prefix ISP2

router bgp ASN

   neighbor IP_ISP1 route-map ISP1_OUT out

   neighbor IP_ISP2 route-map ISP2_OUT out

Best Regards

Please rate all helpful posts and close solved questions