Traditional method of solving group communications problem is by placing a super source with unlimited bandwidth to all sources. In this paper, we show that this method cannot guarantee the fairness within different sources for routing. Also in certain scenarios, the method can lead to wrong conclusion of network achieving higher throughput than it can actually deliver. Two algorithms are presented, one for routing and one for network coding to guarantee that each source has the same fairness and get the sub-optimal throughput for group communications in undirected networks. The throughputs achieved using either of these algorithms (one for routing only and one for network coding) are much better than any current widely-used IP multicast protocols. Between the two proposed algorithms, the algorithm for network coding can have throughput benefit in some scenarios but not always. Here, we show through simulation that network coding does not have constant throughput benefit in undirected networks in group communications scenario with the consideration of fairness within different sources.
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