Optimization Models for Routing in Switching Networks of Clos Type with Many Stages

We present optimization models for the problem of simultaneous routing of connections through a symmetric Clos network, and for the problem of minimal rerouting of previously routed connections when a new connection is to be routed. The models can be used as base for solution methods, such as heuristics for rerouting combined with Lagrangean relaxation. These approaches can together give bounds on the optimal number of rearrangements needed. This is done for Clos networks with three stages, five stages, seven stages, and for an arbitrary number of stages.