PHOENIX: a building block for fault tolerant broadband packet switches

The authors describe PHOENIX, a self-routing, crosspoint buffered 2×2 VLSI switching element being developed for fault-tolerant, flexible broadband packet switching at 150 Mbit/s. A variety of architectures of different sizes can be implemented using this chip as a building block. PHOENIX employs self-checking logic for concurrent error detection. An error indication can be used either to trigger adaptive routing or to switch in a standby fabric. Alternative routing can be used for tolerating faults without having the packets arrive out of order. PHOENIX is ideally suited for implementing multistage interconnection networks. One particular variation of the banyan network, called the MD-Omega network, which employs both space and time redundancy for fault tolerance, is described in some detail. Blocking in PHOENIX based switches is reduced by a combination of crosspoint buffering and internal speedup. An ATM (asynchronous transfer mode) switched based on the MD-Omega network gives reasonable performance under uniform and bursty traffic