Is there a separate multiplayer matchmaking for the Xbox 360 versions of Halo 4 and Halo 3? This may be a very stupid question but I wasn’t sure if it was all one matchmaking system now for those two games meaning that us with the Xbox One H3/4 are playing with the Xbox 360 H3/4 guys.
No. Halo 3 and 4 for the Xbox 360 runs on a peer to peer hosting system for their online multiplayers. For the Xbox One they run on dedicated servers, which is completely separate from the Xbox 360. So in regards to each game, players on the 360 are basically playing a different game from Xbox One players.