There are major changes within Exchange 2013 compared to Exchange 2010. The way Outlook Client connect to Mailbox Server to get its mail data is “simplified” there is no need for middle tier with Exchange 2013. The way I see, as long as Exchange Server and its architecture requires less IOPS to operate, there will be more room for improvements and simplicity.
- User Logs into workstation, it authenticates to active directory with a valid user name and password.
- User opens Outlook at the first time, outlook performs AutoDiscover Lookup to figure out logged in user mailbox GUID.
- Outlook connects to CAS Server, and CAS Authenticates the request (Exchange 2013) using HTTP, it provides mailbox GUID as its endpoint to CAS array.
- CAS takes this information and performs Active Directory lookup
- AD will provide the user information back to CAS Server
- CAS server will make a query to Active Manager Instance, which runs inside the “Microsoft Exchange Replication Service” on all Mailbox Servers
- Active Manager Instance will pull information about requested user mailbox, the name of the mounted database (Active DB) and the Mailbox server name.
- CAS proxies the request to Mailbox Server hosting the active copy of database.
- The data rendering happens on the backed Mailbox Server
- The affinity for user connection is no longer needed on the CAS level.