Design and Analysis of a Media Access Protocol for Star Coupled Wdm Networks with Tt-tr Architecture

This paper presents the design and analysis of a media access protocol implemented in Lightning, an optical WDM network testbed that has been designed for high-performance supercomputer interconnection. The architecture is based on a dynamically reconfigurable hierarchical WDM network to interconnect a large number of supercomputers and create a distributed shared memory (DSM) environment. This paper describes the network media access protocol, called LiteMAC, based on a single tunable transmitter and single tunable receiver (TTTR) per node which exploits the bimodal traffic characteristics of a DSM system. The primary objectives of the protocol design are reduced average latency per packet, support of broadcast/multicast, and support of collision-less communication. The proposed approach is compared to an earlier protocol based on one tunable transmitter and one fixed receiver (TT-FR) per node. The performance of the protocol in terms of average latency and channel utilization is analyzed for varying system characteristics such as number of nodes, channels, and levels.