Recently, I did a test run of a migration from Live Communications Server (LCS) 2005 to OCS 2007. Some things we found out:

1) OCS 2007 doesn’t like SQL 2000 SP4. There’s nothing indicating that it would be unsupported, but we couldn’t get OCS to create the pool with a SQL 2000 SP4 backend for love or money. We eventually ditched it and went straight to SQL 2005, which worked seamlessly.

2) You can make a single-server deployment of OCS Enterprise. Microsoft doesn’t support it, technically. With Enterprise, the pool and the server have to be on separate IPs. The pool DNS record is intended to be pointed at the load balancer you’re using for all those servers (right?). Well, a load balancer for a single server is a bit silly. So, assign the server a second IP address, and change the pool A record to point to that second IP. Clients have to be able to resolve the IP of the pool, and the client MUST see this as a separate IP from the server). Presto – an Enterprise deployment on a single server. That begs the question, if you’re only using one box, why run Enterprise? Well, like I said earlier – it was a test run.

3) OCS works under VMWare Server. Microsoft swear up and down that OCS isn’t supported under a virtualized environment. Sure, they may not help you if you get in trouble, but it worked fine for us. We set up a 2 server pool and the SQL server, and connected several clients to it without any trouble, all under VMWare Server. Even the LCS 2005 pool we were migrating from (in the test lab) was under VMWare. No trouble. We didn’t try Microsoft’s Virtual Server, so that may have some quirks as well.

4) Beware of enhanced presence (EP). If you’re migrating, and looking to run your users concurrently on LCS 2005 and OCS 2007, DO NOT deploy Office Communicator 2007 until the last step. OC2007 when connected to OCS 2007 activates enhanced presence in Active Directory. EP USERS CAN NOT INTERACT WITH NON-EP USERS. This is true even if the users are on the same pool or server. One special quirk we found was that EP can be ticked in the Communications tab in ADUC, but unless the user connects with OC 2007, EP is never activated. Different wording: If you only use OC 2005, nobody uses EP, so you’re fine. So, when you’re doing your migration, save the rollout of OC 2007 till the very end, and everyone can talk to everyone else.

Some resources I found valuable during our testing:

http://forums.microsoft.com/unifiedcommunications/ – Microsoft’s Unified Comms forums. Sometimes slow to reply, but the search engine always has good info.

http://communicationsserverteam.com/ – The OCS team’s blog.

http://blogs.technet.com/toml/archive/2008/01/28/lcs-ocs-coexistence-and-migration-series-allow-block-list-not-in-mmc.aspx – LCSKid’s blog. Great content, helped us tremendously.