The asymmetrical multiconnection three-stage rearrangeable Clos network is considered, where, in general, many-to-many connections are allowed between input and output terminals. The problem of routing the connections over the switches is efficiently solved. The computational complexity is improved from O(mf(3)) to O(f(4)) using a network flow model for the routing problem, where f is the number of first-stage switches and m is the number of second-stage switches; the number of third-stage switches is assumed to be of the same order as f. Note that the O(f(4)) complexity is independent of the number of second-stage switches. Using an appropriate data structure, the computational complexity of an edge-coloring approach to the routing problem is lowered from O(mK(2)) to O(m(f(2) + K log K)), where K is the aggregate capacity of the interconnecting links between all first-stage switches and a second-stage switch; the aggregate capacity of the interconnecting links between a second-stage switch and all third-stage switches is assumed to be of the same order as K. This makes the edge-coloring approach competitive for small values of m and K. (C) 1998 John Wiley & Sons, Inc.