Analysis of the M and M2 Routings in Circuit-Switched Networks

In nonhierarchical circuit-switched networks, calls can be routed to alternate paths if the direct path is blocked. In this paper, we analyze two alternate-path routing rules called the Madmum Free Circuit routing and the Madmum Free Circuit with Minimm Occupied channel routing. For con-venience, we shall call them the M and M2 routings respectively. In the use ofMrouting, acall isrouted toanalternatepath that has the maximum number of free circuits when the direct path is blocked. The M2 routing is an improvement of the M routing in that when multiple alternate paths have the samenumberof freecircuits, thepathwith thesmallesttotaloccupiedchannels is chosen. Analytical results show that M2 routing provides a small but sig-nificant improvement over M routing when the number of alternate paths is large and/or the hunk group size is small. These results are verified by simulation. As the impementation of Mz routing is no more complicated than M routing (both require the same channel occupancy information) and its performance is always better than M routing, M2 routing is deemed a better d e to use