I'm trying to find the best method for keeping a set of redundant servers at a remote site, and being able to fail over automatically. Essentially, I have a backup mail server at a remote site, and I would like to be able to fail over without needing to change IP addresses. I've seen discussions involving spanning VLANs across the WAN, or using NAT to achieve the same effect (although I didn't completely understand the latter).
My goal is to keep the mail server IP the same, and somehow make it available at the remote site. If the remote site is uses the 10.2.x.x subnet, and our primary site uses 10.1.x.x, how would I go about doing this?
Have you considered using LAM ( Local Area Mobility ) ? We use it for AS-400 failover between data centers when we want to keep the IP addresses the same. http://www.cisco.com/warp/public/cc/pd/iosw/ioft/lam/tech/lamso_wp.pdf