In these days, after the request of an user, I have created a hooker/dll injector for the clients and the servers of BF2/2142 of almost any version.
This small tool simply show you how the data, which is sent or received from the network, is read by the game engine.
So you will see all the fields in clear text, the format of the messages, and what means each bits in the packet.
Naturally you can't use this tool with Punkbuster enabled since it modifies the memory of the process, and it's a tool for developers and curious people so the 99% of players and admins don't need it.
http://aluigi.org/papers.htm#others-net