Art-Net is a protocol for sending DMX data over IP networks. Kineme Art-Net Tools provides two patches for interacting with Art-Net devices:

• ArtDmx Sender --- Broadcasts a structure of DMX values to the specified IP Network, Sub-Net, and Universe.
• ArtDmx Receiver --- Receives broadcast DMX values from the specified Sub-Net and Universe.

This quick video (narrated by Beth) explains the basics:

More technical specs and ordering info available from kineme.net