IP/Connection Problems
 

I'm at school and want to play CoD and have to play over the LAN but the LAN is grouped by Dorms and so I can not simply go to LAN on CoD and find a server that someone in another dorm has started. Is there some way to directly connect via IP address as in putting into Favorites? I've tried this and it doesnt seem to work. Also, I can not ping the IP address of those computers I want to connect to. Do I need to add any numbers aside from those in the simple 4-part ip address. Is there a special IP suffix and if so how do I get to it?
Thanks,
Spizzle