A Multi-Level WDM Access Protocol for an Optically Interconnected Multiprocessor System

Scalable, hierarchical, all-optical WDM networks for processor interconnection in multiprocessor systems have been recently considered. The principal objective of this paper is to introduce an access protocol for this type of network which supports a distributed shared memory (DSM) environment. The objectives of the protocol are reduced averagelatency per packet, support of broadcast/multicast, collisionless communication, and exploitation of inherent DSM traffic characteristics. The protocol is based on a hybrid approach that combines reservation access and pre-allocated reception channels for a WDM system. The proposed approach trades maximum capacity for reduced communication latency to improve system response. The performance of the protocol is analyzed through semi-markov analytic and simulation models with varying system parameters such as number of nodes and channels. The performance of the new protocol is compared to a TDM-based protocol and their relative merits are examined. Keywords— parallel computer architecture, photonic interconnections, wavelength division multiplexing, media access protocols, performance analysis.