SXmin: a self-routing high-performance ATM packet switch based on group-knockout principle

Abstract

We propose SXmin: a self-routing, group-knockout principle based asynchronous transfer mode (ATM) packet switch which provides comparable delay-throughput performance and packet loss probabilities at significantly reduced hardware requirements compared to earlier switches. The M/spl times/N SXmin consists of an N/spl times/N Batcher sorter followed by log/sub 2/N-1 stages of sort-expander (SX) modules arranged in the form of a complete binary tree. Each SX module consists of a column of 2/spl times/2 switches with a wraparound-unshuffle input-output interconnection. This enables the hierarchical utilization of the group-knockout principle to expand the number of inputs by a small factor at each stage, resulting in a significant reduction in overall hardware complexity. Routing at each switch is controlled by a single bit. However, in case of contention, a dual bit resolution algorithm is used locally which drops excess packets in a predetermined manner while ensuring global randomness of packet loss over the entire switching network. There are no internal buffers at the individual stages and therefore the internal delay is constant and proportional to the number of stages. The use of simple hardware components and regular interconnections in the SX modules makes the network suitable for optical implementation.