Harmen Van As

Media access techniques: the evolution towards terabit/s LANs and MANs

Abstract Multimedia services, teleconferencing, high-performance visualization and open-system connectivity are expected to accelerate the demand for high-speed and high-performance Local and Metropolitan Area Networks (LAN/ MANs). These must be able to span large geographical areas and to serve large populations. This paper tracks the evolution of the diverse media access techniques used in standardized, experimental and proposed networks through three technology generations. Full exploitation of technological advances has been an ongoing challenge. The first generation, which includes Ethernet, Token Ring, and Token Bus, predominantly covers bit rates of some 10 Mbit/s. The second generation comprises a large variety of network configurations and access mechanisms in the speed range from 100 Mbit/s up to multi-Gbit/s. A remarkable number of basic access schemes and numerous variations reflect the difficulty of simultaneously achieving high throughput, low delay, fairness and scalability. In the third technology generation, architectural and experimental network designs have begun taking advantage of the tremendous transmission bandwidth of more than 20 THz of the optical medium. The intent of this paper is to track this evolution, giving a concise characterization of the diverse access protocols and providing pointers to the related literature.