HA is technically possible over the WAN as long as you have a fast enough pipe. As of 4.0.3 it still isn't officially supported by Cisco, but we are attempting to connect over an OC-3 and believe the latency to be within the thresholds. If we are successful, I will repost.
Has anyone successfully implemented HA over a WAN connection? My two data centers are connected via a Gigabit Ethernet, but the servers will not be on the same subnet. The routing between the two data centers are handled by Cat6K switches with Sup720s.
My impression from Cisco is that they want the servers on the same subnet, no layer 3.
Also, does anyone know if this will be changing anytime soon, like version 4.5?
The information I have received from the BU is that at this point in time, its not supported to have the HA servers remove from each other no matterm the bandwidth. Whether this is 10MB, Gigaman, OC-48, etc. The HA servers are required to be on the same LAN. Its on the horizon and Cisco is working hard to provide the requirement to have a split HA IPCC server.
So going back to my initial post, we had planned to locate the HA servers across an OC-3 with low latency, and do believe it is still possible. Unfortunately, last minute changes in the project stopped us from executing this in production. Again, Cisco unofficially recognizes it is POSSIBLE, but they will not help in any capacity to its function (including TAC). At any rate, if your call center is a critical function of your business, I would not recommend this course of action.
If you decide to attempt this, your biggest challenge will be handling the heartbeat that exists between the HA servers. I believe after 3 consecutive timeouts (verify this part) the servers failover and then it gets messy (disjoint master election of services, DB records incremented independently per server, etc.)
HA is dependent on a very low latency tolerance, thus requiring a very high speed connection (think OC-3 min.) in order for this to be possible.
My source for this information comes from our team that has spoken with SE specialists from Cisco HQ regarding the IPCC HA configurations in their lab.
I'm not one to shoot down ideas, but IMHO, it's probably best to just wait for Cisco to release a supported version.
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