Hello,
Here is a crude diagram of our network:
All of our customer traffic goes through Site A. We have a /21 of Public IPs which are NAT'd to private IPs on the Edge Router.
My goal is to have our /21 advertised to both of our ISPs, so that if Site A goes down then our /21 will reroute to Site B.
The problem is: when the /21 is advertised to both ISPs, I cannot force all inbound traffic through ISP 1 instead of ISP 2. There is always some traffic that tries to come through ISP 2, which I don't want. I only want ISP 2 to push traffic if our BGP Peer to ISP 1 goes down.
Prepending hasn't worked. And I don't think I can do MED since we're using separate BGP Instances.
My current belief is that I'll need to use BGP Communities. I don't know much about Communities, so I'm hoping someone can point me in the right direction.
Thanks
-Sam