AN EFFECTIVE ACCESS-CONTROL METHOD FOR HIGH-SPEED LOCAL-AREA NETWORKSAND METROPOLITAN-AREA NETWORKS

This paper proposes an access protocol with a high throughput for the ultrahigh-speed local area network (LAN) and metropolitan area network (MAN) with the transmission capacity exceeding 100 Mbps. The slotted- ring configuration is suited to the access method for the ultrahigh-sp eed LAN/MAN. Several protocols have been proposed, such as DQDB and AT MR, which, however, have problems in that the throughput in DQDB canno t reach the transmission capacity and the throughput in ATMR decreases when the traffic is nonuniform. In the proposed protocol, the reset s ignal circulates the ring and the fairness of the access is ensured by limiting the number of slots to be sent by each node by the window si ze. The number of slots to be sent is not limited if none of the downs tream nodes has data to be sent, This helps to realize: a high through put independently of the traffic situation. As the result of performan ce evaluation, it is verified that the proposed protocol is useful in the following two points: (1) approximately 1.8 times higher throughpu t is realized compared to the existing protocols when the traffic conc entrates to a particular node; and (2) the delay time is suppressed to a love value for burst traffic such as video.