Redundant Microcomputer-Controlled 3-Stage Clos Network For System-Availability Enhancement

This paper analyzes a redundant microcomputer-controlled 3-stage Clos network to enhance system availability. Lower bound of number of Middle Switch Segments is established for the existence of one backup path to support each primary path which connects each pair of input/output ports to the switch network. This lower bound also satisfies the strictly non-blocking condition established by Marcus in 1977. The paper proves that a full-loaded network with single loads is the worst case for availability analysis. Upper bounds on the number of I/0 ports are established for networks of several switch-card designs to enhance availability. An availability model for redundant microcomputer-controlled network is presented with numerical results. The approach is unique and new.