An optical fibre-based Local Backbone Network

The paper describes an optical fibre system for local distribution which is under development. Based on its function of serving a limited number of high-volume sources, the system is called a Local Backbone Network. The network has a star topology and is designed to carry both interactive and bulk data, voice and video teleconferencing. Up to eight arms, each consisting of full-duplex optical links operating at a rate of 40 Mbps, radiate from a central switch. User traffic enters the system through user access nodes at the ends of the arms. The guiding philosophy of the system is based on taking advantage of the large available transmission bandwidth in order to simplify processing in the central switch. Within the switch a form of time slot interchange is used to route traffic between the arms. A flexible strategy based on time division multiplexing is used to divide the bandwidth among users in a way which guarantees an upper bound for user delay. The network design philosophy, as well as a detailed description of the operation of the network, are presented.