Will the multiplayer be on the same disk?

In Halo: CEA, will be play on the Multiplayer maps on the Halo: Anniversary disk, or will we use the disk to download the maps to our console as DLC, and then we can use them with Reach? This was never clear to me.

1 disc.
If you buy CEA, you get the CE campaign and 6MP maps to play in the Anniversary Playlist. The 7th map is a FF map that you will likely get to play FF in.
It all launches from the main menu.

If you wish, you can install the maps to your HDD and then you will have them playable with Reach if have Reach. This gives access to the maps in other playlists other than Anniversary.

It will not be much longer after the release of CEA that the 7 maps will be a DLC option for those that do not want to buy the CE campaign.