Abstract: An apparatus for communicating with a network comprises a data packet pipeline and a monitoring element. The data packet pipeline is configured to transfer data between a buffer and a network socket. The monitoring element is configured to provide an indication of an operational performance parameter for at least one component of the data packet pipeline thereby enabling an operational problem within the pipeline may be isolated based on the indication.

Abstract: A switching fabric connects input ports to output ports. Each input has an input pointer referencing an output port, and each output has an output pointer referencing an input port. An arbiter includes input and output credit allocators, and an arbitration module (matcher). The input credit allocator resets input credits associated with input/output pairs and updates the input pointers. Similarly, the output credit allocator resets output credits associated with input/output pairs and updates the output pointers. The matcher matches inputs to outputs based on pending requests and available input and output credits. A scheduler schedules transmissions through the cross-bar switch according to the arbiter's matches.

Abstract: Data packets are received at a communications node. Each of the received data packets is associated with one of a set of different service classes. Packets corresponding to the received data packets are transmitted to recipients. The order in which the data packets are transmitted is controlled based on the transmission rate and the service class of the packets.

Abstract: A system for shaping traffic from a plurality of data streams includes a queuing stage having a plurality of first-in, first-out shaping queues, the queuing stage being configured to classify incoming entries of traffic, and to assign an incoming element of traffic to a selected queue of the first queuing stage depending on characteristics of the element, the queuing stage further being configured to allocate bandwidth to each of the queues using time division multiplexing. A method for shaping traffic from a plurality of data streams includes providing a plurality of first-in, first-out queues; assigning traffic to the queues depending on the characteristics of the traffic; and controlling traffic flow out of the queues using a bandwidth allocation table.

Abstract: A system for shaping traffic from a plurality of data streams comprised of a first queuing stage configured to shape traffic from the data streams and having a plurality of shaping queues; and a second queuing stage coupled to the first queuing stage and configured to manage congestion from the first queuing stage that occurs when multiple of the shaping queues become eligible to send traffic at substantially the same time.

Abstract: The present invention relates to high speed communications, in particular, to an interface device between a transmitting device and a receiving device of a transmission system, wherein the transmitting device is capable of automatic compensation of cross-talk timing errors in the interface device, for a group of signals, by using information stored in a storage attached to that interface device. Preferably, the data stored in said storage comprises data on interconnections between said first and second plurality of terminals and data on crosstalk timing errors in said transmission lines relating to a specific data pattern, for each of said stored interconnection.

Abstract: A method for managing congestion in a stack of network switches includes the steps of receiving an incoming packet on a first port of a network switch for transmission to a destination port and determining if the destination port of the packet is a monitored port. Thereafter, the method determines a queue status of the destination port, if the destination port is determined to be a monitored port, and preschedules transmission of the incoming packet to the destination port if the destination port is determined to be a monitored port.

Abstract: A method of providing virtual output queue feedback to a number of boards coupled with a switch. A number of virtual queues in the switch and/or in the boards are monitored and, in response to one of these queues reaching a threshold occupancy, a feedback signal is provided to one of the boards, the signal directing that board to alter its rate of transmission to another one of the boards. Each board includes a number of virtual output queues, which may be allocated per port and which may be further allocated on a quality of service level basis.

Abstract: This invention is intended to realize with ease flow control and quantization error reduction in a data transfer operation executed via the IEEE 1394 serial bus. A FIFO once holds data supplied from a decoder and outputs the data in a predetermined send timing relation. At this moment, a counter counts the number of packets to sent from the FIFO to an IEEE 1394 bus. In order to increasing data transfer quantity in accordance with a send command issued by a register, a data packet is sent at transfer of an empty packet. In order to decrease data transfer quantity, an empty packet is sent in a timed relation in which a data packet is sent. A data quantity monitor requests the decoder for supplying data or stopping thereof via a data input controller so as to prevent the FIFO from overflowing or being emptied in accordance with flow control.

Abstract: A musical tone data communications system having a unit for generating MIDI data of a musical performance by a player, a unit for transmitting the generated MIDI data over a communications network and a unit for receiving the transmitted MIDI data and reproducing musical tones corresponding to the MIDI data in real time.

Abstract: A method and system for detecting and controlling congestion in a multi-port shared memory switch in a communications network. The proposed congestion management scheme implements a local and a global congestion monitoring process. The local monitoring process monitors the queue depth. When the queue depth for any queue exceeds a queue length threshold a congestion control mechanism is implemented to limit incoming data traffic destined for that queue. Additionally, the global congestion monitoring process monitors the shared memory buffer and if the traffic thereto exceeds a shared memory buffer threshold a congestion control mechanism limits incoming traffic destined for any output queue which has been exceeding a fair share threshold value.

Abstract: A method and system for controlling a plurality of pipes in a computer network, including at least one processor for a switch, the at least one processor having a queue, the plurality of pipes utilizing the queue for transmitting traffic through the switch, wherein each pipe is assigned a priority ranking class, each class has a unique priority rank with respect to each of the other classes, the ranks ranging from a highest priority rank to a lowest priority rank. A transmission probability is calculated for each pipe responsive to its priority rank. If excess bandwidth exists for the queue, the transmission probability of each pipe is linearly increased. Alternatively, if excess bandwidth does not exist, the transmission probability for each pipe is exponentially decreased. Packets are transferred from a pipe to the queue responsive to the pipe transmission probability and priority rank.

Abstract: A system and method of moving information units from an output flow control toward a data transmission network in a prioritized sequence which accommodates several different levels of service. The present invention includes a method and system for scheduling the egress of processed information units (or frames) from a network processing unit according to service based on a weighted fair queue where position in the queue is adjusted after each service based on a weight factor and the length of frame, a process which provides a method for and system of interaction between different calendar types is used to provide minimum bandwidth, best effort bandwidth, weighted fair queuing service, best effort peak bandwidth, and maximum burst size specifications. The present invention permits different combinations of service that can be used to create different QoS specifications.

Abstract: A scheduler apparatus provides bandwidth guarantees to individual data packet flows as well as to aggregations of those flows (referred to as “bundles”) in a completely transparent manner, i.e., without using any additional scheduling structure. For each bundle, the scheduler determines the ratio between the bandwidth nominally allocated to the bundle and the sum of the individual bandwidth allocations of the flows that are currently backlogged in the bundle. The scheduler uses that ratio to modulate the timestamp increments that regulate the distribution of bandwidth to the individual flows. In this manner, the greater the ratio for that bundle, the more the bandwidth that each backlogged flow in the bundle receives.

Abstract: A wireless communication system is described for allocating limited network access according to priorities designated for requested transactions of wireless communications. The wireless network has a number of access links for transmitting transactions for wireless communications. A plurality of wireless communications devices request transmission of transactions on the wireless network. A designated priority level is associated with each transaction. In response to the transaction requests, an access control manager in the wireless network schedules transmission of transactions when all of the plurality of access links are occupied, by authorizing a transmission of a transaction of higher priority than another transaction that is being transmitted, and discontinuing the transmission of the transaction of lower priority.

Abstract: There is provided a packet scheduler for managing output awaiting packets stored in a plural of queue blocks each having a weighting coefficient settled based on an output guaranteeing bandwidth, whereby an output order for the head packets is stored in respective queue blocks. The packet scheduler includes means for controlling selection of a queue having a packet to be sent at the highest priority, based on scheduled output time information obtained by calculation using management information of the output awaiting packets and the weighting coefficient of each queue, and means for correcting processing carried out in the controlling means based on the current time information. The arrangement enables to ensure assignment of vacant bandwidth in a fair manner while suppressing erroneous operation deriving from deviation of a scheduled packet output time from the real time caused by a calculation error or the like in WFQ calculation.

Abstract: A satellite system is provided that includes a receive antenna system to receive one of C-band and/or Ku-band signals and a transmit antenna system to transmit one of C-band and/or Ku-band signals. A payload section may be coupled between the receive antenna system and the transmit antenna system. The satellite system may provide broadband communications at C-band and/or Ku-band.

Abstract: The present invention focuses on the aggregation of flows belonging to different classes of non-guaranteed-delay traffic into a single FIFO queue in a downstream stage of the multi-stage switch. These include the guaranteed flows requiring bandwidth reservation, the best-effort flows that require a fair share of the excess bandwidth, and the flows that require both types of guarantee. We disclose a credit-based backpressure scheme which selectively controls the traffic originating from the previous stage of the system while achieving the goal of meeting the requirements of the individual flows. The credit function is maintained for each controlled traffic component in the aggregate session, and its objective is to balance the actual arrival rate of the component with the service rate dynamically granted by the downstream scheduler. The number of flows that can be aggregated is related to the complexity of maintaining the credit functions for the different traffic components.

Abstract: Method and apparatus for queuing packets are disclosed. In one aspect, a method may comprise assigning each packet a first value; dynamically assigning each packet a second value; and queuing each packet for transmission using the first and second values.

Abstract: A method for selecting packets comprises pipelining execution of packet selection processes so that execution of each of the packet selection processes occurs at different levels of a scheduling hierarchy. At least two different packets are selected at two different times in response to execution of the packet selection processes.

Abstract: A data reception unit for receiving a plurality of data streams over a data channel, the data streams being received as amounts of data and 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 comprising: a data stream memory comprising a plurality of data stream storage areas, each for storing data from a respective one of a set of the data streams, and an escape buffer; a first storage information memory for holding first storage information for facilitating storage in the respective data stream storage area of data from the set of the data streams; and a data storage controller for, for each received amount of data, receiving the identity portion of the amount of data and performing a storage operation comprising: accessing the first storage information memory; and if the first storage information memory holds first storage information for the data stream identified by the identity portion, storing the

Abstract: A multiport network device includes output port logic, priority logic, a memory, and memory logic. The output port logic generates output port data that identifies output ports to transmit received packets. The priority logic generates priority data that identifies priorities of the received packets. The memory stores the output port data from the output port logic and the priority data from the priority logic. The memory logic receives priority data relating to one of the received packets from the output port logic, determines whether the memory stores output port data relating to the packet, ignores the received priority data when the memory stores no output port data relating to the packet, and when the memory stores output port data relating to the packet, transmits the received priority data and the stored output port data to the identified output port.

Abstract: An apparatus and method of maintaining a route table within a network device lists data identifying specific routes of interest that have changed. The routes of interest may be within a given set of routes. Specifically, after the given set of routes are registered with the apparatus, it is determined if any of the routes in the given set has changed. Data identifying each route in the given set of routes that has been determined to change then is listed.

Abstract: A network device that controls the communication of data frames between stations includes a number of receive ports that receive data frames from the stations and a number of output ports that transmit the data frames to their intended destinations. The network device also includes a number of output queues that store data forwarding information associated with the received data frames. The network device partitions each of the output queues into a number of portions corresponding to the priorities supported by the network device. The number of portions and the size of each portion of the output queues may be programmable by the user.

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 congestion control method and apparatus in a cell-switched data switch. The switch attaches a tag with a discard processing indicator, such as a particular random number, to all cells belonging to a same packet. In determining which cells to drop when running a congestion control algorithm such as RED, the switch compares the discard processing indicator of the cells with a discard criterion and only drops cells that conform with the discard criterion.

Abstract: A data switching device has ingress routers and egress routers interconnected by a switching matrix controlled by a controller. Each ingress router maintains one or more virtual output queues for each egress router. The switching matrix itself maintains a head-of queue buffer of cells which are to be transmitted. Each of these queues corresponds to one of the virtual output queues, and the cells stored in the switching matrix are replicated from the cells queuing in the respective virtual output queues. Thus, when it is determined that a connection is to be made between a given input and output of the switching matrix, a cell suitable for transmission along that connection is already available to the switching matrix. Upon receipt of a new cell by one of the ingress routers, the cell is stored in one of the virtual output queues of the ingress router corresponding to the egress router for the cell, and also written the corresponding head of queue buffer, if that buffer has space.

Abstract: A switching system includes a switch fabric that includes groups of buffers for each port interface device that communicates with external communication devices through an Ethernet plane. The port interface device is formed to receive congestion ratings reflecting buffer usage within the switch fabric for each device coupled to transmit and receive packets through the switching fabric and to determine whether to route to the switching fabric or drop the packet based upon the congestion rating of the destination device and upon a quality of service rating for the packet.

Abstract: A system provides flow control in a network device. The system includes output queues that correspond to the output ports of the network device, a mask register, a first logic device, and a second logic device. Each of the output queues generates signals relating to the priority levels associated with the corresponding output port when at least a predetermined number of items are stored in the output queue. The mask register generates mask signals relating to the priority levels associated with a particular one of the output ports. The first logic device generates first flow control signals related to the priority levels associated with the particular output port based on the signals from the output queues and the mask signals associated with the priority levels and the particular output port. The second logic device generates a second flow control signal based on the first flow control signals from the first logic device.

Abstract: The assignment result reception circuit 11 receives the accumulation assignment result from the external portion, and sends the already-assigned input port and output port information to the assignment request mask circuit 12. The assignment request mask circuit 12 uses the already-assigned input port and output port information received from the assignment result reception circuit 11, performs the mask process on the connection assignment request received from the external portion, and sends its result to the M×N scheduler circuit 13. The M×N scheduler circuit 13 determines the assignment of the port connection in accordance with the information received from the assignment request mask circuit 12, and sends the connection assignment result to the external portion and the assignment result transmission circuit 14.

Abstract: A method and apparatus to perform buffer management for media processing are described.

Abstract: Methods and apparatus are disclosed for propagating timestamp floors throughout a packet switching system and using the timestamp floors received at a first component of the packet switching system to determine when a packet may be sent from a packet switching system. Each input of a first stage of a packet switching system maintains a floor register which is updated by copying the timestamp from each arriving packet. In some systems, if a packet is not received during a packet time, the timestamp is automatically updated, typically by adding a fixed time value. Periodically, the first stage switching element forwards a timestamp floor to the next stage switching elements. In one implementation, this distributed timestamp floor is the lesser of the earliest timestamp in one of the floor registers in the input queues, and the earliest timestamp in an output queue for the particular next stage switching element.

Abstract: The invention relates to a buffer memory, method and a buffer controller for queue management usable in an ATM switch. An object of the invention is to achieve a high frequency throughput of data cells in the buffer memory. This object is achieved by using a buffer memory which is organized as 256*(424+8) SRAM-cells. The memory is used for holding ten queues, one for each incoming channel and two free-queues containing idle cells.

Abstract: In an asynchronous transfer mode switch, a plurality of queues is provided for accumulating transfer cells, and a queue assignment processing section, receives a message for establishing a connection and assigns to the connection one of the queues having a forwarding rate close to a declared rate included in the message and not exceeding the declared rate.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A system, method and article of manufacture are provided for transferring a packet from a port controller to a switch fabric in a switch fabric system. Notification is received indicating that a packet has been processed in the port controller. The processed packet is assigned and linked to an output priority queue. Subsequently, the packet is retrieved via the link and transmitted from the port controller to the switch fabric.

Abstract: A network packet switching engine is described. The switching engine generates a priority to be associated with a packet of data. The switching engine receives a packet of data. Based on information in the packet (e.g., source address, destination address, tag priority, receive port) and other information (e.g., candidate priorities, a set of flags, and a priority table), the switching engine determines a priority for the packet.

Abstract: A broadband telecommunications switch (1), for switching packets of data received on a plurality of input ports (5) to plurality of bandwidth limited output ports (10), comprising for each input port (5) a control processor (22) which operates to send request data for each of a plurality of switching periods to each output port (10), which request data is representative of a requirement for communications bandwidth from said output ports (10) sufficient to accommodate packets of data received at said input ports (5) for switching to said output ports (10) for the switching period. Each of said bandwidth allocators (24) responds to said request data by generating bandwidth allocation data appertaining to an allocation of a share of the bandwidth of the output port (10) to the input port (5), which share of bandwidth said input port (5) uses to switch data from said input ports to said output ports during said switching period.

Abstract: A method, for use with systems that transmit information in data packets, includes running a first scheduling method on at least one first-stage scheduler device which guarantees first connection parameters during a transmission process. The first connection parameters correspond to transmission rates for the data packets. The method also includes storing a queue identifier in packet headers of the data packets and determining to run, based on the queue identifier, a second scheduling method on a second-stage scheduler device which limits second connection parameters during the transmission process. The second connection parameters correspond to higher transmission rates for the data packets than the first connection parameters and precedes the first scheduling method. The method further includes bypassing the first scheduling method when the transmission rates are not to be limited.

Abstract: Message cells that are allocated to virtual connections having different priorities are transmitted jointly over at least one transmission line of an ATM system working according to an asynchronous transfer mode. While being transmitted via the respective transmission lines, these message cells pass through a buffer memory individually allocated thereto. Given a buffer memory exhibiting a specific filling degree, one or more message cells from message cells of a selected virtual connection of low priority, which are, stored at the moment in the buffer memory, are discarded with the arrival of a message cell on the respective transmission line belonging to a virtual connection of relatively high priority, and dependent on the number of message cells stored for this virtual connection having low priority.

Abstract: A method and system is provided for use on a switching hub in a packet-switching network for handling the output queuing of received packets in the switching hub to be more efficient and cost-effective. This method and system is characterized in the provision of a broadcast output queue in addition to the output queues at the ports of the switching hub, with the broadcast output queue being exclusively used for sequencing broadcast packets and the output queues being used exclusively for sequencing unicast packets. When a broadcast packet is received, the method and system assigns a free-list link node to the broadcast output queue, but not to the output queues, and meanwhile adds one to the broadcast count in each of the last link node in each of the output queues.

Abstract: A novel N×N Crossbar Packet Switch is disclosed, which crossbar switch is based on a distributed port architecture, asynchronous output port arbitration, support of non fixed-size packets (cells), support for virtual channels (VC) and/or priority, and which only requires 2*N*N control lines for the arbitration.

Abstract: A scheduler and method for use in ATM and packet communication systems applies a no-per-connection-timestamp discrete-rate scheduling technique which does not require the computation and storage of one timestamp per connection, and only maintains a single timestamp per supported service rate. The elimination of the per-connection timestamps has no negative effect on the delay bounds guaranteed by the scheduler. The total implementation cost of such schedulers which approximate the Generalized Processor Sharing (GPS) policy is reduced, since there is less complexity involved in maintaining and sorting the timestamps for all connections.

Abstract: Adaptive jitter buffer management, e.g., for playout of packetized data transmitted over a network. Playout delay is iteratively adjusted based on changing network traffic characteristics by varying the release threshold in a jitter buffer. The adjustment is carried out by evaluating three quantities: (1) average packet transit time over the network; (2) jitter of the packet transit time; and (3) additional waiting time due to the presence of out-of-sequence packets. This invention reduces negative effects of jitter and/or transmission irregularities, such as late arrival of packets and out-of-sequence packets, while maintaining relatively low playout delay and relatively high quality of service.

Abstract: An apparatus and method for searching for preambles in a base station of a mobile telecommunications system employing a CDMA system. The method comprises the steps of inputting oversampled samples of each chip associated with a first antenna from an access slot boundary and storing the inputted samples in a first buffer, inputting oversampled samples of each chip associated with a second antenna after the lapse of a predetermined delay from the access slot boundary and storing the inputted samples in a second buffer, reading samples in a period of a plurality of chips from the first and second buffers and correlating the read samples with scramble codes to generate signatures corresponding respectively to a plurality of hypotheses, calculating an accumulated energy value of each of the signatures, and sorting the signatures by identical ones and selecting one with a maximum accumulated energy value from among the sorted signatures.

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 scheduling apparatus of the present invention includes a first element which stores a pair comprising (1) an identifier for identifying a communication event and (2) time information. The time information shows the time for executing the communication event and is represented by floating point data having an accuracy necessary for the communication event. The scheduling apparatus has a second element which reads out the identifier from the first element by using current time information which is represented by the floating point data. A communication control apparatus of the present invention includes a first element which outputs time information and an identifier which identifies the communication event corresponding to the time information. The time information shows time of executing a communication event and is represented as floating point data having an accuracy necessary for communicating the communication event.

Abstract: A method for access control in a wireless network having a base station and a plurality of remote hosts includes the optional abilities of making dynamic adjustments of the uplink/downlink transmission ratio, making dynamic adjustments of the total number of reservation minislots, and assigning access priorities by message content type within a single user message stream. The method of the invention further provides for remote wireless host paging and for delayed release of active channels by certain high priority users in order to provide low latency of real-time packets by avoiding the need for repeated channel setup signaling messages. In the preferred embodiment, there are N minislots available for contention in the next uplink frame organized into a plurality of access priority classes. The base station allows m access priority classes.

Abstract: A method and apparatus for preserving loop fairness. Some embodiments include a dynamic half-duplex feature. One aspect includes a communications channel system and method for preserving loop fairness that includes a first channel node having one or more ports, each port supporting and attached to a fibre-channel arbitrated-loop serial communications channel. One of the ports will arbitrate for control of that port's attached channel, wherein control of the channel loop, once arbitration is won, a fairness-preserving apparatus causes control of the communications channel to be released based at least in part on whether a predetermined amount of use has occurred between the first port and the communications channel. In some embodiments, the predetermined amount of use includes a transfer of a first predetermined amount of data. In some embodiments, release of control of the channel is inhibited if less than a second predetermined amount of data remains to be transferred.

Abstract: Data traffic such as cell streams in an ATM communication network frequently contain data destined for multiple output ports having different transmission data rates. In order to accurately schedule such traffic a clocking signal unique to each output data rate is required. This invention provides systems and methods for generating the necessary clock signals utilizing a single timing reference.