Exchange 2013 has reached RTM, and is now available for sale. In late February, we expect the Service Packs to be available that allow us to deploy Exchange 2013 into existing Exchange environments. With Exchange 2013, we will have several new options for load balancing the Client Access servers and I would like to quickly go over those options now.

Exchange 2013 Architecture

Exchange 2013 has been designed with some architecture changes from the previous versions of Exchange. One of the biggest changes is that Exchange 2013 has been released with only 2 server roles. Those roles are the Client Access Server and the Mailbox Server. The functionality of the Hub Transport and Unified Communications roles from the previous two versions has been added into these two roles. Additionally the CAS role been redesigned so that its only job is to proxy connections to the proper Mailbox Server. (There is a single instance where the CAS server redirects connections instead of proxying them, but that is not relevant to this post). In doing this redesign, one of Microsoft’s major goals was to enable better High Availability options for the CAS role.