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.

Abstract: A method and apparatus for prioritizing ATM cells within time transmission slots is disclosed. The present invention takes cells which have been prioritized by traditional priority circuitry and adds to them information regarding the need to begin transmitting cells in the current time slot in order to ensure that a list of cells which must be transmitted by a future time slot can all be transmitted timely. If no list of cells in a future time slot mandate immediately transmission in the current time slot, a cell from the standard prioritization buffer will be transmitted. If, on the other hand, a subsequent slot contains so many entries that one of its cells must be transmitted in the current slot in order to ensure that all cells in the list are transmitted before their time deadline, one of the cells from the subsequent time slot list will be transmitted in lieu of the standard priority cell of the current slot.

Abstract: A packet-based transmission system is disclosed in which resource management packets containing cell rate information are processed at a single ABR server. The server receives forward resource management packets and routes them without modification to their destination. The server also receives reverse resource management packets which it processes by updating their corresponding cell rate information based, for example, on cell rate information received from the forward cells.

Abstract: A new, efficient approach to ATM connection table lookup minimizes the number of tables and memory lookups through use of hash coding and binary table search techniques. The virtual connection information associated with an incoming ATM cell is hash coded. The hash code provides a compressed representation of the virtual connection information--allowing the address space of a table accessed based on the hash code to be much smaller than the maximum number of possible virtual connection combinations that can be encoded in the ATM cell header without restricting the set of possible virtual connection combinations. A binary search based on the cell's virtual connection information can be used to efficiently select, from plural records accessed based on the hash code, the particular search record corresponding to the cell's connection.

Abstract: An Asynchronous Transfer Mode (ATM) switching device handles active and passive leaves. For a multicast connection being routed through the switching device, there is set up both a passive leaves queue (PLQ) for each physical output link and a leaf table for each leaf of the multicast connection. The leaf tables are added and removed for each connection on the fly as each leaf is added or removed. For a passive leaf of the multicast connection, the leaf table for the passive leaf is linked to an appropriate one of the passive leaves queues. However, upon reception of a cell from a switch core, the appropriate one of the passive leaves queues is activated by being linked to an activation queue (AQ). Thereafter a pointer is set, in an active leaves queue (ALQ), to the leaf table indicated in the appropriate passive leaves queue (PLQ). There is an active leaves queue for each physical output.