Abstract: A novel scalable-port non-blocking shared-memory output-buffered variable length queued data switching method and apparatus wherein successive data in each of a plurality of queues of data traffic is distributed to corresponding cells of each of successive memory channels in striped fashion across a shared memory space.

Abstract: A queue control system and method for scheduling fixed size traffic elements for transmission on a link from a number of queues. The system comprises a memory, queues and queue processor. The memory stores a linear array, where each array index corresponds to a transmission priority and is capable of referencing a list of queues. Each queue has an assigned weight and an associated calculation remainder variable stored in a memory. Queues referenced by a low value array index are selected for transmission before queues referenced by higher value array index. The queue processor is arranged so that to repetitively select a queue for transmission in dependence on the referenced position of the queue in the array, and to operate a predetermined function for moving the reference to a queue selected for transmission to a new array index.

Abstract: The invention relates to a method and means for managing packet queues in switches. The switch has a shared memory split in a small internal memory and a large external memory. There is limited bandwidth to the external memory. The method comprises the steps of dividing a data stream incoming on the input ports intended for respective output ports into two parts, of which the first part is to be sent to an internal queue belonging to at least one output port and the second part is to be sent to the external memory. The incoming data stream may be identified as belonging to flow groups and the division of the data stream is then performed e.g. such that flow groups with a higher priority than a division threshold are sent to said internal queues in the first part, while flow groups with priority lower than said threshold are sent to the external memory in the second part.

Abstract: A method and apparatus provides QoS shaping/provisioning scheme for a data communications switch, such as a DiffServ aware router or a 802.1Q aware bridge, in which distinct internal and outbound priority values are assigned to a packet based on flow properties associated with an inbound packet. The flow properties used to assign the internal and outbound priority values may include at least one value from a packet field that is not dedicated to defining QoS. The internal priority value provides a priority to the packet during processing in the switch. The outbound priority value is applied to the packet in lieu of the inbound priority value prior to transmitting the packet from the switch. The flow properties used to determine the internal and outbound priority values may include, for example, Layer 2, Layer 3, and Layer 4 information encoded in the packet.

Abstract: A router comprising a priority level distinguishing means for distinguishing the priority level of a packet by referring to the information contained in the header of the packet, a routing table where an output path comprising one or more output lines can be mapped to each level of priority, an output path determining unit that searches the routing table and determines an output path to be used for sending out packets, and a preferential delivery controller that executes delivery control in accordance with the priority level for each output line corresponding to the output path. In response to a fault state in a preferred output line, the router can reroute high priority packets over an alternative output line while maintaining priority. The router may also calculate a distribution ratio to determine the optimal load for each output line for a given packet priority.

Abstract: An apparatus and method that optimizes the data rate for forward link data transmissions in a spread-spectrum communications system 106 is provided. The spread-spectrum communications system 106 comprises a wireless infrastructure 103, at least one wireless mobile receiving device 105, and an radio frequency (RF) forward link 104 between the wireless infrastructure 103 and the wireless mobile receiving device 105. The data rate of the RF forward link 104 is optimized in the wireless infrastructure 103 by estimating or measuring the bottleneck link speed of the data transmission and adjusting the data rate for the RE forward link 104 according to several embodiments of a data rate optimization algorithm. The algorithm creates an optimum range for the data rate of the RF wireless link 104 which maximizes system capacity and reduces transmission delays to the wireless mobile receiving device 105.

Abstract: A switching system connectable to a communications network and configured to handle logical multicast data without degrading the flow of other data through the system. The switching system includes a plurality of input ports, a plurality of output ports, and a plurality of queues for buffering streams of data units being routed through the system. The switching system further includes at least one meter for metering data units to ensure that the data units conform to predetermined Quality of Service criteria. The logical multicast data is metered once at the meter and subsequently replicated and transmitted onto the communications network a predetermined number of times at an output port so as not to degrade the flow of other data through the system.

Abstract: Disclosed is an apparatus employing an efficient buffering scheme for analyzing the Layer 7 content in packet data sent from a first node to a second node within a computer network. The apparatus includes a first device having a buffer and one or more first processors. The apparatus also includes a second device having one or more second processors. The first device is a physically separate device from the second device. The second processor of the second device is configured to manage the buffer of the first device, and the first processor is also configured to analyze packet data accessed from the buffer.

Abstract: In one embodiment, a method comprises receiving a packet of a number of packets for storage into an egress port. The egress port has a number of queues associated with nodes of a hierarchy tree. The hierarchy tree has a level of nodes associated with contexts for the number of packets. The method also includes storing the packet into a queue of the number of queues of the egress port based the associated node within the hierarchy tree.

Abstract: It is an object of the present invention to provide a data switching method capable of impartially selecting a plurality of input ports by a simple circuit configuration. The data switching method according to the present invention includes an up-counter, a down-counter, a counter selecting circuit for selecting either of a counted value by the up-counter or a counted value by the down-counter, a port selecting circuit for selecting one of a plurality of input ports based on an output from the counter selecting circuit, and a buffer for accumulating a packet supplied from the input port selected by the port selecting circuit. The port selecting circuit alternately selects the up-counter and the down-counter to switch the ascending order and the descending order of the import priority of the input ports at every time the packet is imported, thereby impartially selecting each of the input ports.

Abstract: The invention performs a cell switching operation of switching cells of a connection being higher in transmission rate than an existing switch port by means of the existing switch. Namely, the invention bundles a plurality of input ports and a plurality of output ports respectively to make a high-speed input port and a high-speed output port, separates cells inputted through the high-speed input port so that they have an ordinary transmission rate, and multiplexes the cells to be outputted through the high-speed output port so that they have the transmission rate of the high-speed output port. Furthermore, the invention gives a cell a number indicating the order in which said cell has been inputted from each of the input ports including the high-speed input port and corrects the order of the cells outputted from the output buffers into the order in which they have been inputted, on the basis of the numbers added to the cells.

Abstract: A system for scheduling in a high-speed switching environment includes multiple output queues, multiple counters that each correspond to one of the output queues, and an output port. The output port can read packets from the output queues in a series of rounds. In each of the rounds, the output port can access at least one of the output queues, increment the counter corresponding to the output queue by a first amount, determine whether the counter corresponding to the output queue is at or above a particular level, and, if the counter is at or above the particular level, read one or more packets from the output queue that each have a length and decrement the counter by a second amount corresponding to the one or more lengths of the one or more read packets.

Abstract: A method and apparatus for buffering data units in a communication switch that allows for configurable monitoring of the buffer contents is presented. Such an apparatus includes a context table that stores a plurality of independent group identifiers for each connection. Although the group identifiers may include a partition group identifier and a loss group identifier that is dependent on the partition group identifier, additional group identifiers are included in the context table for each connection that are independent of other group identifiers in the context table. Such a context table may be dynamically reconfigured in order to group connections for buffer monitoring operations related to congestion detection, traffic shaping, and data admission with respect to buffering. When a data unit is received corresponding to a particular connection, the context table is referenced to retrieve the set of group identifiers corresponding to that connection.

Abstract: An output buffer type ATM (Asynchronous Transfer Mode) exchange device and a multicast control method enable retrieval processing to bit map table for the sake of multicast control to delay, and which are capable of answering to be large capacity of the bit map table. The multicast control method of the output buffer type ATM exchange device multiplexes the cell inputted from a plurality of input ports during input cell period. The method accumulates unicast cell from among the cell distributed from a time division multiple bus into output buffer corresponding to the output port respectively. The method outputs the unicast cell to corresponding output port while synchronizing with output cell period.

Abstract: A network switch as well as methods, systems and computer program products for controlling congestion at a granularity of less than a link are provided. Such finer granularity may be provided by pausing traffic at a source port level of a network switch. The network switch which transmitted a message which resulted in congestion being detected is notified of the congestion and pauses the communications from the source port of the message while maintaining communications over the link from other source ports. Such source port level congestion control may be provided by a network switch having a sub-queue of its output queues where each sub-queue corresponds to an input port. Source port level pausing of transmissions may then be provided by pausing the sub-queue associated with a source port.

Abstract: A method and apparatus for providing a virtual output queue (VoQ) from a received set of data packets in a multi-service system. Each packet is divided into at least one partition, including a last partition that includes packet information, such as error status and packet length. The system receives the packet from a flow, parses the packet into partitions, including a first partition and the last partition, places each last partition into a linked list based on a time when the last partition was received, links the last partition to the first partition, and employs the linked list as the output queue. This system allows for rapid compilation and transmission of different sized packets, and obviates the need for the receiving processor to wait for the last partition to discard a bad packet.

Abstract: An improved combined Switching Data Unit (SDU) queuing discipline for unicast and multicast (Protocol Data Unit) PDU forwarding at a switching node is provided. Multicast SDU descriptor pointers are replicated stored in entries of a First-In/First-Out queue portion of a hybrid output port queue. Unicast SDU descriptor pointers are chained in entries of a linked list queue portion of the hybrid output port queue. Servicing of the hybrid queue uses hybrid queue counters, and inter-departure-counters stored in multicast FIFO queue entries to keep track of the number of unicast SDU linked list entries to be services between the multicast FIFO queue entries. The combined hybrid queue derives storage efficiency benefits from linking unicast PDUs in linked lists and further derives benefits from a simple access to multicast PDU entries.

Abstract: An ATM cell buffer read control system prevents over-rate due to excessive use of an extra line capacity with guarantee of a minimum output rate in a WRR system. The ATM cell buffer read control system effectively uses a band by distributing an extra band with a ratio of number of ATM cell number per connection with guarantee of minimum output band per connection according to preliminarily set ratio of output ATM cell number per a given period. The ATM cell buffer read control system makes judgment whether the output band after distribution of the extra band falls within a reference output range.

Abstract: The invention relates to a switch arrangement for a packet-switched telecommunications network. The switch arrangement comprises several input ports and several output ports, a switching fabric (SWN), and an output unit (OUi) between each output port and the switching fabric, the output unit comprising an output buffer (OB) in which outbound packets are stored. In the switch, virtual connections are used for packet switching and serial numbers in packets belonging to each virtual connection are used to identify the relative order of the packets. The output unit (OUi) maintains virtual connection-specific information on the serial number of the currently anticipated packet, and the packets belonging to a given virtual connection are ordered in the correct sequence in accordance with the serial numbers of the packets.

Abstract: Multi-level buffer system dynamically allocates storage for data units arriving at network gateway, and retrieves stored data units according to hierarchical schedule. Minimum and maximum thresholds associated with system resource and storage availability determine acceptance and storage of data units. Data units are accepted preferably if all threshold criteria are met. Threshold criteria may be determined from reserved minimum buffer length, calculated maximum buffer length, or random early discard-type algorithm applied separately to each buffer level. Optionally, buffer management applies to non-hierarchical storage systems.

Abstract: The present invention discloses a queue servicing method and system for servicing queues containing packetized data in a network switching device. The invention includes initializing parameters for multiple queues, such as a quantum value, a borrow enable flag, and a first counter maximum value. The invention increments a first counter for each of the queues with the quantum value and donates the quantum value to a share counter, when the value of the first counter exceeds the first counter maximum value. The invention then selects a packet from each of the queues to be dequeued and transmitted on an output channel of the network device. The packet is dequeued and transmitted when a byte length of the packet is less than or equal to the value contained in the first counter or when the borrow enable flag of the queue is enabled and the byte length of the packet is less than or equal to a sum of the values contained in the first counter and the share counter.

Abstract: A data reception unit for receiving a plurality of data streams over a data channel. The data streams are received as amounts of data, each amount of data comprising a data portion including data from a data stream and an identity portion identifying that data stream. The data reception unit comprises a data stream memory comprising a plurality of data stream storage areas, and a buffer; a first storage information memory for holding first storage information a processing unit, and a data storage controller. The data storage controller, for each received amount of data, receives the identity portion of the amount of data and performs a storage operation based on the identity portion.

Abstract: A bi-modal network connection device provides a high level of adaptability to changing connection-level loading patterns without sacrificing speed and configurability. The device can function in both a static mode and a traffic-adaptive mode. Benefits include the ability to provide high buffer utilization and throughput in ATM networks which either have very dynamic connection-level statistics or have poorly understood traffic characterization, plus the ability to assure users of minimal latency delays if desired.

Abstract: The invention relates to a switching fabric arrangement for a packet-switched telecommunications network. Packets arriving at the switching fabric are assigned a time stamp depending on their time of arrival. Time stamp information relating to the packets to be transported is transmitted to at least some of the switching elements, and in at least some of the switching elements, the relative order of the packets to be sent is established on the basis of the received time stamp information in such a way that on each outgoing link (IL) from the switching element, the packets are in the sequence indicated by the time stamps.

Abstract: Disclosed is device for suppressing a rise in the operating speed of the buffer controller in an ATM switch and reducing the operating speed in the write decision section of the switch. In a memory-write control circuit, data to be written to a memory having a predetermined memory capacity is provided with a priority. The circuit renders a write-enable/disable decision in such a manner that data of low priority will not be written to the memory in excess of a threshold value and data of high priority will not be written to the memory in excess of the memory capacity. A write decision circuit compares the threshold value and present queue length if the input data is valid data and, moreover, the data has a low priority, and compares the maximum capacity of the memory and the present queue length if the input data is valid data and, moreover, the data has a high priority, thereby to render an enable/disable decision with regard to writing of the input data to the memory.

Abstract: The present invention relates to handling of data units in a node of a communication system. The data units are distributed in a plurality of transmission queues based on priority parameters that associate with the data units. The queues are weighted such that the weight of a queue defines the relative share of resources allocated to said queue in relation to the resources that are to be allocated to the other queues. The assigned weights can be adjusted based on information of the amount of logical connections that associate with the respective queue.

Abstract: The present invention is a method and apparatus for processing data packets in the outbound module of a space-based cell switch. The present invention uses an expanded set of queuing parameters to determine an output queue in which to store each data packet. The method includes the steps of selecting an expanded set of queuing parameters (202), establishing several output queues (204) based on combinations of the expanded set of queuing parameters, receiving data packets in a communications uplink (206), examining the header portion of each received data packet (208, 210 and 212), determining an appropriate output queue in which to store the data packet (214 and 216), and switching the received data packets to that appropriate output queue (218). The present apparatus includes several input modules (102), a switch control output (114) connected between the input module (102) and a switch fabric (104), and a several output modules (106) connected to the switch fabric (104).

Abstract: A packet memory system including a memory space having a multiplicity of addressable memory locations for the storage of data packets, pointer control means for generating a write pointer which progressively defines where data is to be written to the memory space and a read pointer which progressively defines where data is to be read from the memory space and an ageing clock which defines a succession of intervals. The pointer control means generates a ‘current’ pointer and a ‘discard’ pointer and for each interval is operative to cause the ‘current’ pointer to correspond to an immediately previous value of the write pointer and to cause the discard pointer to correspond to an immediately previous value of the said current pointer. In this manner the portion of the memory space between the ‘discard’ pointer and the read pointer denotes data which has been in said memory space for at least two of said intervals.

Abstract: A packet switch for switching variable length packets, wherein each of output port interfaces includes a buffer memory for storing transmission packets, a transmission priority controller for classifying, based on a predetermined algorithm, transmission packets passed from a packet switching unit into a plurality of queue groups to which individual bandwidths are assigned respectively, and queuing said transmission packets in said buffer memory so as to form a plurality of queues according to transmission priority in each of said queue groups, and a packet read-out controller for reading out said transmission packets from each of said queue groups in the buffer memory according to the order of transmission priority of the packets while guaranteeing the bandwidth assigned to the queue group.

Abstract: A network processing device stores and aligns data received from an input port prior to forwarding the data to an output port. Data packets arrive at various input ports already having an output queue or virtual output queue assigned. A buffer manager groups one or more packets destined for the same output queue into blocks, and stores the blocks in a buffer memory. A linked list is created of the trunks, which is an ordered collection of blocks. The trunks are sent to a high speed second memory and stored together as a unit. In some embodiments the trunks are split on boundaries and stored in a high speed memory. Once the trunks are stored in the high speed second memory, the corresponding data is erased from the write combine buffer memory and the pointers that made up the linked list are returned to a free block pointer pool. The data can then be read from the high speed second memory very quickly, passed through a switching fabric, and placed back on the computer network for its next destination.

Abstract: A switching method and apparatus operates as a work conserving network device. An arbiter using an arbitration algorithm controls a switch fabric interconnecting input ports and output ports. To switch cells, a virtual output queue of an input port is selected that corresponds to an output port with a lowest occupancy rating and a request is sent to this output port. In a greedy version of the algorithm, input ports may send requests to the lowest occupied output port for which they have a cell. In a non-greedy version, requests may only be sent if that input port has a cell for the lowest occupied output port in the entire network device. An output port that receives one or more requests from input ports uses an input port selection algorithm to select an input port from which to receive a packet. After as many input and output ports are matched as is possible in a phase, the packets for those matched ports are transferred across the switch.

Abstract: A network switch in a packet switched network includes a plurality of network switch ports, each configured for sending and receiving data packets between a medium interface and the network switch. The network switch port includes an IEEE 802.3 compliant transmit state machine and receive state machine configured for transmitting and receiving network data to and from a medium interface, such as a reduced medium independent interface, respectively. The network switch port also includes a memory management unit configured for selectively transferring the network data between the transmit and receive state machines and a random access transmit buffer and a random access receive buffer, respectively. The memory management unit transfers the network data between the transmit and receive state machines and the respective buffers based on prescribed interface protocol signals between the memory management unit and the transmit and receive state machines.

Abstract: A method and apparatus is for buffering data cells in a queuing element is presented. Each queuing element includes a partitioned buffer, where the partitioned buffer includes a plurality of partitions. Each of the partitions stores data cells received by the queuing element. Storage of the data cells into the partitions is accomplished by using an array of logical queues. Each logical queue of the array of logical queues maps data cells corresponding to that logical queue to a particular partition of the plurality of partitions. More than one logical queue may map data cells to a particular partition. Each partition may include a reserved portion, where each logical queue that maps to the partition may map a portion of its data cells to the reserved portion. The resources of the reserved portion to which a logical queue maps data cells are reserved to that specific logical queue and cannot be utilized by other logical queues.

Abstract: Provided is a packet communication apparatus capable of instantly transmitting information requiring urgency without lowering data transfer efficiency even during a communication. The packet communication apparatus comprises first and second packetization sections 8 and 9 for converting signals transmitted from signal processing sections 2 and 7 to packets of predetermined forms, priority packet interleaving means 10 for interleaving the packet from the second packetization section 9 in the packet from the first packetization section 8 even during a transmission of the packet from the first packetization section 8 when the packet from the second packetization section 9 is input thereto, and a transmitter 3 for transmitting the packet output from the priority packet interleaving means 10 to a packet transmission communication medium 4.

Abstract: The present invention is directed to synchronizing notification messages transmitted to egress control units to allow an even distribution of the messages. A plurality of packet buffer units (PBUs) may concurrently transmit notification messages to a particular egress control unit in response to packets received from a plurality of ingress control units. Each PBU includes a notification queue associated with the egress control unit for storing notifications generated by the PBU. Notifications in the notification queues are ordered according to the ingress units triggering the notifications. Notifications in each notification queue are retrieved via a time-driven pointer that is initialized to a different start entry position for the notification queues in each PBU. This allows each PBU to transmit, at any given time, notifications to the egress control unit that are associated with a different ingress unit.

Abstract: A ring interface is coupled to a current node in a ring network having a plurality of nodes and corresponding ring interface for each of said nodes. The ring interface includes a ring input port operative to conduct upstream message packets from a previous node to the ring interface, a ring output port operative to conduct message packets to a next node of the ring network, and a bypass queue operative to buffer message packets. A receive queue buffers message packets before passing them on to the current node. An address filter is coupled to the ring input port to receive the upstream message packets, read their destination addresses and pass them to the bypass queue if the addresses correspond to another node and pass them to the receive queue if their addresses are that of the current node.

Abstract: A bi-modal network connection device provides a high level of adaptability to changing connection-level loading patterns without sacrificing speed and configurability. The device can function in both a static mode and a traffic-adaptive mode. Benefits include the ability to provide high buffer utilization and throughput in ATM networks which either have very dynamic connection-level statistics or have poorly understood traffic characterization, plus the ability to assure users of minimal latency delays if desired.

Abstract: An apparatus and method that optimizes the data rate for forward link data transmissions in a spread-spectrum communications system 106 is provided. The spread-spectrum communications system 106 comprises a wireless infrastructure 103, at least one wireless mobile receiving device 105, and an radio frequency (RF) forward link 104 between the wireless infrastructure 103 and the wireless mobile receiving device 105. The data rate of the RF forward link 104 is optimized in the wireless infrastructure 103 by estimating or measuring the bottleneck link speed of the data transmission and adjusting the data rate for the RF forward link 104 according to several embodiments of a data rate optimization algorithm. The algorithm creates an optimum range for the data rate of the RF wireless link 104 which maximizes system capacity and reduces transmission delays to the wireless mobile receiving device 105.

Abstract: A method and system for forwarding data-packets in a data-over-cable system, is provided. The data-packets received by the head-end of the data-over-cable system are sorted according to the Quality-of-Service identifiers assigned to the destination for the respective data-packets. The sorted data-packets are forwarded subsequently in accordance with the Quality-of-Service settings corresponding to their respective Quality-of-Service identifiers. Data-packets that cannot be transmitted in accordance with their respective Quality-of-Service identifiers are cached for transmission at a later time point.

Abstract: A multiple phase cell dispatch scheme, in which each phase uses a simple and fair (e.g., round robin) arbitration methods, is described. VOQs of an input module and outgoing links of the input module are matched in a first phase. An outgoing link of an input module is matched with an outgoing link of a central module in a second phase. The arbiters become desynchronized under stable conditions which contributes to the switch's high throughput characteristic. Using this dispatch scheme, a scalable multiple-stage switch able to operate at high throughput, without needing to resort to speeding up the switching fabric and without needing to use buffers in the second stage, is possible. The cost of speed-up and the cell out-of-sequence problems that may occur when buffers are used in the second stage are therefore avoided. A hierarchical arbitration scheme used in the input modules reduces the time needed for scheduling and reduces connection lines.

Abstract: A method of scheduling queue servicing in a data packet switching environment is provided. The method includes a sequence of cyclical steps. The output queues are scheduled for servicing on a least credit value basis. An output queue is selected from a group of output queues associated with a communications port. The selected output port has at least one Payload Data Unit (PDU) pending transmission and a lowest credit value associated therewith. At least one PDU having a length is transmitted from the selected output queue and the credit value is incremented taking the length of the transmitted PDU into consideration. The transmission of PDUs is divided into transmission periods. Once per transmission period credit values associated with output queues holding PDUs pending transmission are decremented in accordance with transmission apportionments assigned for each output queue. The method emulates weighted fair queue servicing with minimal computation enabling hardware implementation thereof.

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 for performing logical multicasting within a network switch are disclosed so as to permit a downstream network device to perform cell forwarding in a manner which resembles spatial multicasting. A logical multicast cell has a connection identifier associated with the cell within the switch. The connection identifier is employed to initiate a series of lookup operations to generate unique VPI/VCI addresses which are transmitted out of an output port of the switch as copies or leaves of the multicast cell. Successive look-ups of outgoing VPI/VCI addresses for a logical multicast cell are performed using a chain bit to indicate when all leaves of the cell have been transmitted. Leaves of a logical multicast cell are transmitted to the downstream network device from one output cell buffer of a plurality of output cell buffers associated with the output port of the switch so as to minimize the likelihood of blocking and so as to minimize cell delay variation.

Abstract: Several rotator switch architectures are provided that enhance performance of a basic rotator switch. The rotator switches having double buffered tandem nodes, multiplexing two or more sources onto each tandem node, partitioning the rotator into two or more parallel space switches, two or more rotator planes multiplexing front/to source and destination nodes to provide data path redundancy, priority queueing on source nodes scheduled locally or globally, or redundancy in the schedulers are shown.

Abstract: A data transmission and receiving network includes a plurality of nodal apparatus for sending and receiving digital data in variable length data slots. The nodal apparatus includes a storage device for maintaining a conflict resolution queue representative of nodal apparatus sending simultaneous requests for transmission causing a collision during a control minislot. The nodal apparatus also includes a transmission queue stored in the storage device. The transmission queue is indicative of nodal apparatus that have successfully transmitted during a minislot and are thus queued for transmission of data in data slots. The apparatus includes a transmitter for sending a variable length data slot signal comprising digital data in response to the state of the transmission queue. The nodal apparatus also includes a receiver for receiving a variable length data slot signal.

Abstract: A system for implementing flow control in an information network such as a local area network (LAN) utilizing a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) as specified by the IEEE standard 802.03. The information network transmits computer information such as computer data between various computer systems coupled to the information network. The information network includes information network switches capable of routing information packets received via its input ports to its output ports. The received packets are held in buffers of the output ports before being transmitted via the output ports. A portion of each output port buffer is allocated to each input port. The information network switch provides a control packet such as a PAUSE frame to an upstream source operably coupled to the input port in response to the level occupancy of the portion of the buffer allocated to the input port exceeding a first level.

Abstract: Disclosed is a priority control method using a single output queue wherein an output priority of a packet not undergoing convergence is improved by exchanging the order of a packet undergoing convergence or a packet which may undergo convergence with the order of a packet not undergoing convergence.

Abstract: A system and method for flushing cells in an ATM network sets an interval timer during which it would be expected that an active physical output would indicate it could accept a cell. When an interval elapses, a physical output that has not indicated it is ready to accept a cell is marked as disabled and may remain so until the output is reset. Cells in an output queue to a disabled cell are flushed during periods when no higher priority cells are available to be sent.

Abstract: An ATM switch supporting multicast transmissions and efficient transmission of frames. A cell is received on a multicast connection and transmitted on several branches/ports. Instead of copying a multicast cell several times for each output branch, only one copy of each multicast cell is maintained. The cell order and the stored cell data form a physical queue. Several logical queues are maintained, one for each output branch. In one embodiment, linked lists are used to maintain the queues. A cell in the physical queue is deleted after all logical queues traverse that cell. A shared tail pointer is used for all the logical queues to minimize additional processing and memory requirements due to the usage of logical queues. The queues enable cells forming a frame to be buffered until the end of frame cell is received, which provides for efficient handling of frames.

Abstract: A multicast queue for controlling cell traffic to individual output queues in a multicast group in accordance with the backpressure information generated by each output queue. One or more destinations asserting the backpressure signal are identified and, in response, the corresponding one or more destinations are removed from the ‘distribution list’ in the routing tag associated with the connection. In this fashion, a cell that originated at a multicast source queue can be transmitted to the remaining destination queues that are not in a congested state. Cell traffic will cease only to those destination queues that generated the backpressure signal indicating that they are full. If the congestion at an output port is removed, the corresponding backpressure bit is reset and cell traffic resumes to that particular output port.