Hmm, can't edit my post. Anyway, this is what I've learned so far with my noobish protocol analysis skills, using Halo 3 as a base.
When the xbox is searching for games, it broadcasts 42 bytes of data over UDP, from a source address of 0.0.0.1 to the IPv4 broadcast address 225.225.225.225 on port 3074. Pretty standard LAN play with UDP. (If anyone wants this capture PM me, but it's pretty useless).
I'm assuming that when it gets a reply to this is when the exchange occurs. However I can't test this because I don't have two 360s, nor do I have the network hardware to do a proper capture.
However, if anyone well-enough equipped were to take some captures and post them, others could analyze them.
This post has been edited by freyyr890: Jul 2 2008, 02:22 AM