All Exchange 2010 network communications in a diagram
This is a great resource if you ever need to refer to network flow between different roles and well as different clients to server communications. This is too good of information to pass on without sharing.
I am sure you will benefit from it if you have anything to do with Exchange server.
Huge thanks to Michel for creating this very helpful document.
Originally posted at http://blogs.technet.com/bshukla