Abstract: A method/system for estimating cell rate is provided. The cell rate to be reported to an ATM (asynchronous transfer mode) source may be estimated using a previously calculated cell rate parameter weighted in a manner dependent upon whether a rate for the connection is high or low. An averaging parameter may be adjusted for each calculation so that for low rate connections newly measured data is more heavily weighted, and for high rate connections newly measured data is less heavily weighted. Relatively accurate and quick estimates for both high bandwidth and low bandwidth connections are achievable.

Abstract: A method for the relative flow control of a data flow, and a switch in which the method may be applied, are described. A buffer unit that reaches a certain degree of fullness sends a message to all units from which it receives data that it cannot receive any more data or that it can only receive at a reduced rate. The message is forwarded by each unit that receives it, to each unit from which it receives data and comprises a level indicator field, which is incremented for each unit it passes. For each unit passed a field is also added, identifying the unit from which it was received. Each unit is denoted by its number among all units receiving packets from the level above it. The message may be valid either for a certain period of time or until a new message is transmitted indicating that the problems have ceased.

Abstract: In a switch having two parallel planes (A, B) for providing redundancy, cells are received from the two planes in redundancy terminating unit comprising that first the cells are separated whether they are ordinary switched cells, called unicast cells, or cells which are switched or copied to a plurality of the outputs of the planes, these cells being called multicast cells. At each cell time a selection of one received cell is made by a selector control unit (3) and this selection is made substantially at random, among possible received unicast cells and a multicast cell as stored in a FIFO (35) having an output register (37). If received cells have different priorities the random selection is made among cells having the maximum priority of the priority of the received cells. A unicast cell which is not selected, is discarded but a non-selected multicast cell remains in the register until it is selected.

Abstract: A method and apparatus schedule transfer of information packets, each information packet switch inlet port being associated with a packet transfer scheduler for scheduling transfer of information packets. A cell is sorted into a first queue structure according to its information packet switch outlet port, and for each outlet port, according to its logical channel.

Abstract: An Asynchronous Transfer Mode (ATM) switching device (110) has a switch core (112) connected to a plurality of incoming VC channels and an egress port (116) connected to receive cells from the switch core. The egress port has both a plurality of pre-merge VC queues (144) and a plurality of merge VC queues (140). Cells received from the switch core are stored in one of the plurality of pre-merge VC queues in accordance with their incoming VC channel. A merge controller (132) determines when one of the pre-merge VC queues has a complete packet of cells, and enters the packet of cells into an appropriate one of the merge VC queues.