Abstract: In a best effort type service of an ATM communication network for circulating an RM cell, a subscriber's switchboard holds the latest route information, and the RM cell is used for short distance communication between the communication terminal and subscriber's switchboard. For a plurality of connections accommodated in the switchboard and using a transmission line or a route in common, information on the allowable transmission rate, the actual transmission rate, the full bandwidth and full input bandwidth of the transmission line or the route, and the number of connections using in common the transmission line are collected and held. A transmission rate acceptable for the caller's terminal is calculated for each connection on the basis of the information. An increase of a memory capacity is restricted by providing a common buffer and managing it by a pointer value. A list of cells which have arrived simultaneously is prepared, and is managed by the pointer value.

Abstract: When bandwidth in an ATM network is controlled so as to increase in accordance with a user request, there is a considerable delay from the occurrence of the request until the bandwidth is actually changed; and there is therefore a need to control the traffic flowing in ATM network transmission paths faster and more flexibly. There is also a need to decrease the probability of overbooking occurring when deciding whether or not to accept a bandwidth change request. Route information that includes information relating to residual bandwidth is therefore collected in advance by subscriber switches that serve terminals. In response to a request from a user, a subscriber switch alone replies rapidly. During this process, the fact that there are a plurality of bandwidth change requests within the same residual bandwidth measurement period, is considered and a portion of the measured residual bandwidth is held for other bandwidth change requests. This enables the delay to be shortened.