Wayne at Artistic Licence invented artnet... check out the Artistic Licence website for details and info.

I can recommend his book: Rock Solid Ethernet
http://www.artisticlicence.com/index..._id=&order_id=

Also check out the DMX workshop software to understand more about how it all works...
http://www.artisticlicence.com/index..._id=&order_id=

the first 5 pages of this manual is usefull to give an explanation:
http://www.artisticlicence.com/WebSi...es/art-net.pdf
(p5 onwards is compex..>!!)

If you need more specific info - let me know

Simon