Abstract: A method and system construct an O-tree and I-tree for a rearrangeably-blocked digital symmetrical matrix (DSM) network. The method includes the steps of receiving a plurality of parameters including a tree forming instruction for forming the I-tree and O-tree, an input switch parameter, an output switch parameter, and middle switch parameters. From these parameters, the method and system yield a set of feasible nodes for rearranging the DSM network to make the desired connection. The method and system are modified to terminate at the first feasible node of a modified I-tree or a modified O-tree. Also, both a rearrangement method and system and a DSM network control method and system are provided that use either the I-tree and O-tree construction process or the modified I-tree and modified O-tree construction process. Furthermore, a parallel rearrangement algorithm is provided for even further enhancement.