Being familiar with these 6 items before introducing an OCS R2 pool into an OCS deployment (with an existing OCS 2007 R1 pool) could save you some valuable time and frustration.
Familiarize Yourself with the Microsoft OCS R2 Migration Guide
The TechNet online migration guide is available here: Migrating From Office Communications Server 2007. Note, if you are coming from LCS 2005, there is a migration guide available as well: Migrating From Office Communications Server 2005.
Move your OCS Global Settings from the System Container to the Configuration Container in Active Directory
See the “Move Global Settings” in the “OCS 2007 R2 Migration from 2007” guide. Aaron Tiensivu has a very practical good write-up about the process and the associated details: http://blog.tiensivu.com/aaron/archives/2009/01/06.html.
Ensure your OCS 2007 Servers are Up-to-Date
There have been several OCS 2007 high priority updates in the last year; some of them will help your OCS R2 co-existence. Knowledge Base Update 956389 from November, 2008 addresses several issues for example, and you will want to have that update package installed. Most updates are applicable to all OCS server roles. For more updates and the current top OCS issues, visit the Office Communications Server 2007 Solution Center.
The R2 Edge requires an R2 Pool or R2 Director
An OCS 2007 (R1) Director or Front-End is not a supported next hop for an OCS R2 Edge.
Side-by-Side OCS R2 Edge Server Has Implications
It is not possible to deploy an R2 Edge and R2 Director side-by-side with a R1 Edge and maintain the PIC and Federation functionality for the newly migrated R2 pool users. This sounds more complex than it is. The external DNS entries can only point to one inbound Edge entry-point, so you cannot have both the R1 and R2 Edge running in parallel.
The R2 Migration Guide calls this out in the “Choose a Deployment Strategy” (http://technet.microsoft.com/en-us/library/dd572317(office.13).aspx) section: “‘Federation’ and/or ‘PIC’ functionality is not possible for any R2 migrated user until after the edge has been also been upgraded to R2”.
The OCS 2007 and OCS 2007 R2 Administrative Consoles Cannot Be Installed on the Same Computer
See my previous blog entry regarding Quick Facts about the OCS R2 Administrative Tools.
Inside OCS 