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Multicast, the ability to efficiently send data to a group of destinations, is becoming considerably important in several application scenarios e.g. VoIP, video calling, media streaming and more. It is widely understood that two forms of multicast are important. Firstly, a broadcast-like mechanism where data is sent to a very large number of destination and secondly a narrowcast mechanism, where data is sent to a small number of destinations. The second of these multicast descriptions fits XCAST.
Multicast schemes in general can be used to minimize bandwidth consumption. As a multicast scheme, XCAST can be used to minimize bandwidth for many applications which involve very large numbers of small, changable multicast groups. Additionally, XCAST eliminates the per session signaling and per session state information of traditional IP multicast schemes and this allows XCAST to support very large numbers of multicast sessions. Therefore, XCAST was traditionally considered for IP telephony, video conferencing and networked games. However, in recent work we have discovered that XCAST can be considerably useful in Peer-to-Peer systems which use parallelism to send messages to small, dynamic groups of nodes.
To test our theory that XCAST can be used to benefit P2P applications, we first needed to implement the XCAST protocol in a simulation environment. We chose the SSFNet network simulator. A copy of our XCAST implementation, along with an example application can be found at the link below. We do not provide a copy of the SSFNet simulator, you need to download this from the SSFNet web site. Our implementation should be extracted into the SSFNet source tree (as modifications were made to some SSFNet classes).