Here are a few pointers to where you can get more information on
multicast programming. This is not an exhaustive list, but all pointers
included have source code available.
A simple server/client pair of multicast applications that send and
recieve the current time. This source accompanies the Internet
Multicasting article on multicast programming by Bob Quinn in Oct.
'97 issue of Dr. Dobbs Journal. http://www.ddj.com/ftp/1997/1997.10/timecast.zip