Multicast, the ability to efficiently send data to a group of destinations. is becoming increasingly important for the applications such as IP telephony and video-conferencing. The traditional IP multicast is economical in the case of large group applications, but on the other hand, it becomes expensive for its members if the groups are small. The applications where the number of simultaneous multicast sessions can be very large and the number of members in a group is small are getting more and more.
Explicit multicast(Xcast) can support a very large number of small multicast sessions by explicitly encoding the list of destinations in the data packets, instead of using a multicast address. The sources in the Xcast system encodes the list of destinations in the Xcast header, and then sends the packet to a router. Each router along the way parses the header, partitions the destinations based on each destination's next hop, and forward a packet with an appropriate Xcast header to each of the next hops.
In this paper, we developed Xcast system over IPv6 on Linux kernel by the specifications provided by D. Ooms. But there are still some problems. In this system, we can't develop Xcast applications which bring the advantages of Xcast into relief. And we assume all en-route router is Xcast-enabled. For actual deployment in network. we must implement the tunneling scheme also. We hope to provide the basis on which Xcast applications can be developed.
