A GROWABLE PACKET (ATM) SWITCH ARCHITECTURE - DESIGN PRINCIPLES AND APPLICATIONS

This paper focuses on the generic problem of designing a large N x N(N > 1000) high-performance, broadband packet (or ATM) switch. Despite recent advances in switch architectures, practical switch dimensions continue to be severely limited by both the technological and physical constraints of packaging (e.g., chip or board sizes). Here, we focus on switch growability: we provide ways to construct arbitrarily large switches out of modest-size packet switches, without sacrificing overall delay/throughput performance. We propose and study a growable switch architecture based on three key principles: a) a generalized knockout principle exploits the statistical behavior of packet arrivals and thereby reduces the interconnect complexity, b) output queueing yields the best possible delay/throughput performance, and c) distributed intelligence in routing packets through the interconnect fabric eliminates internal path conflicts. Other attractive features of the proposed architecture include the guarantee of first-in-first-out packet sequence, broadcast and multicast capabilities, and most important of all, compatibility with variable-length packets, which avoids the need for packet size standardization. In a broadband ISDN example, we show a 2048 x 2048 configuration with building blocks of 42 x 16 packet switch modules and 128 x 128 interconnect modules, both of which fall within existing hardware capabilities.