Supporting TCP connections in wormhole routing and ATM networks

Abstract

An interesting lightweight switching technique for local area and campus environments is wormhole routing, in which the head of a packet, upon arriving at an intermediate switch, is immediately forwarded to the next switch on the path. The current proposals and products of wormhole routing networks provide a connectionless and lossless transport of variable-size data units, aiming at minimal latencies, but without any quality-of-service guarantee. Wormhole networks therefore push at an extreme the networking paradigm of the Internet, adopting technical solutions for high-speed networking that are opposite to those taken in ATM. The aim of this paper is to perform a simulation-based comparison between the wormhole routing and ATM transport techniques in high-speed networking scenarios. The behavior of the two information transport techniques is studied in mesh topologies where a few interfering TCP connections in overload interact with a uniform background traffic. Our results show that a larger hardware and software complexity is required to ATM switches with respect to wormhole routing switches in order to provide a comparable throughput to TCP connections. By contrast, ATM is more capable to handle severe congestion situations and to provide better fairness.