The progress of ITU-T and ANSI standards on SDH/SONET is accelerating the evolution of transmission systems all over the world. The advanced operation administration and maintenance (OAM) functions it provides makes it possible to create a self healing ring network which protects against failure. This self-healing ring consists of add/drop multiplexers (ADM's). The switch in the ADM plays an important role in achieving self-healing operation. In this paper, self-healing ring architecture and operations are analyzed in order to determine the requirements for the ADM switch. On the basis of this result, new space division switching methods, which significantly reduce the amount of hardware needed, are proposed. A parallel processing architecture which makes it possible to develop a low-cost large-scale switch is also devised. Finally, a developed switch LSI chip is presented. Combining two identical chips with the proposed parallel processing architecture, a 32/spl times/32 STS-3 switch (5 Gb/s throughput) with an STS-1 time slot interchange (TSI) function is realized.