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. Two alternate-path routing rules called maximum free circuit routing and maximum free circuit with minimum occupied channel routing, the M and M ² routings, respectively) are analyzed. In the use of M routing, a call is routed to an alternate path 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 same number of free circuits, the path with the smallest total occupied channels is chosen. Analytical results show that M² routing provides a small but significant improvement over M routing when the number of alternate paths is large and/or the trunk group size is small. These results are verified by simulation. As the implementation of M² 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 rule to use