I used to work for a company that produced very precise and clever tools for analysis of network application performance between any number of machines. You can tell it watch a certain protocol, or traffic between certain machines, and track what's going on. It keeps a track of how long each packet stays at each machine, and does very analytical graphics that present time spent on the network, time spent at each host involved, time spent in the buffers versus on the line (offer analysis).. etc.

http://www.compuware.com/products/ecosystems/appvantage/

It's a little $$$ but it is a beautiful tool!

Calvin