Extending the Birkhoff- Von-Neumann switching strategy to multicast switches

Abstract

This paper extends the Birkhoff-von Neumann unicast switching strategy to the multicast case. Using a graph theoretic model we show that the rate region for a traffic pattern is precisely the stable set polytope of the pattern's 'conflict graph', in the no-fanout splitting case. Computing the offline schedule is equivalent to fractional weighted graph coloring which takes polynomial time for perfect graphs. For a general conflict graph, we show that deciding achievability of a given rate vector is NP-hard, but can be done in polynomial time for the case of moderate multicast load. The result naturally leads to an offline schedule. © IFIP International Federation for Information Processing 2005.