Benefits consolidating servers
With the Exchange 2013 release, Microsoft consolidated its previous Exchange server role architecture from five roles down to two.While the re-architecture may seem drastic, it should prove a positive change for admins in the long run.Typically, fewer, smaller applications that peak at different times drive the highest consolidation.Increase utilization of existing hardware from 10 to 15 percent, up to 80 percent Reduce servers at a to-1 ratio Reduce hardware and operating costs by as much as 50 percent About the book: It's one of the most effective ways to lower TCO of a company's datacentre.Of course there were several long-term payoffs: more efficient use of existing hardware, a more responsive Exchange Server setup and more granular management.It required a bit of settling in, but once admins understood why it was done, it made more sense.Many aspects that were formerly implemented through unified messaging are now divided between the CAS and mailbox roles.
Because the Exchange 2007 and Exchange 2010 edge transport role doesn't exist in Exchange 2013, a certain degree of legacy compatibility must exist between the two systems, and it does.
This means that front- and back-end servers can reside in entirely different Active Directory sites.
Prior to Exchange 2013, they were essentially forced to live in the same site.
I've compiled key points regarding the Exchange 2013 server role changes that are worth keeping in mind as you prepare to migrate an existing Exchange organization to Exchange Server 2013: Aside from the fact that network admins now only have one protocol to deal with, client traffic is also that much simpler.
Any RPC calls -- such as MAPI traffic from Outlook -- is wrapped in HTTPS and sent thusly.This also means RPC endpoints (in the CAS array) don't exist anymore either. This is another nice consequence of the change to how the front- and back-end communicate with each other.