Abstract: A system and method for using forward error correction (FEC) to improve transmission reliability for data packets transmitted over packetized data networks, such as voice packets transmitted over an Internet Protocol (IP) network is disclosed. Packets containing error data are transmitted separately from corresponding voice packets. The error packets are transmitted a predetermined number of frames before the voice packets, to increase the probability that either the voice packet or error packet will be received. The error packets are preferably created using a Reed-Solomon algorithmn. The amount of error correction transmitted may be adaptively adjusted based on the reliability of the network connection.

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: A method and apparatus are provided for frame packing for nodes in a network. In one example, the method includes receiving packet streams from network nodes; parsing the packet streams into individual calls; grouping the individual calls having the same destined node together into grouped calls; packing the grouped calls into single packets; and sending the single packets to the destined nodes.

Abstract: A system and method for providing reliable transport of TDM data over a packet network, while maintaining a constant TDM data stream at a receiving end. TDM data is stored in a frame, which is assigned a sequence number. The frame is sent in a packet over the packet network, a timer is set on the sending side, and a copy of the packet is stored in a buffer. On the receiving side, the frame is removed from the packet, an acknowledgement frame is sent to the sending side, and the frame is stored in a receive buffer. If a frame is missing or corrupted, a null set frame is stored in the buffer. The frame with the lowest sequence number is read out of the receive buffer and sent to a TDM data stream. The acknowledgement causes the timer to be cancelled. If the timer expires before being cancelled, a copy of the packet is resent. If a duplicate frame is not received before the null set frame is read out of the receive buffer, the null set frame is sent to the TDM data stream.

Abstract: A method and apparatus are provided for providing multiple qualities of service to different virtual network connections. In one example, the method receives a token of a cell descriptor of data traffic of a virtual network connection. It is determined whether the token is in conformance with contracted bandwidth parameters of the cell descriptor to obtain a conformance status. Based on the conformance status, one of the following steps is performed: the token is inserted into a first random access memory configured to store the token for immediate output, or the token is inserted into a second random access memory configured to store the token for non-immediate output.

Abstract: Methods, apparatus, and systems are presented for communicating structured data in a system utilizing devices having different data processing capabilities. The methods, apparatus, and systems involve transmitting a unit of data from a first device, wherein the unit of data comprises at least a version-specific portion and a version identifier associated with the version-specific portion, receiving the unit of data at a second device distinct from the first device, processing the version-specific portion at the second device if the second device recognizes the associated version identifier, and disregarding the version-specific portion at the second device if the second device does not recognize the associated version identifier. Disregarding the version-specific portion may comprise examining a data length field in the data unit associated with the version-specific portion to determine a length value and skipping an amount of data corresponding to the length value.

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 uses an ATM Adaptation Layer of type 2 (AAL2) standard mechanism to define efficient support for Variable Rate Coding (VRC). The VRC in this context typically refers to codecs, which adapt their rate to information content variations in speech and audio. Such VRC results in lower average rate than the constant rate codecs or use of constant rate codecs coupled with silence suppression (SS), currently deployed in voice over ATM schemes using AAL2. Possible ATM transport, trunking and access applications encompass both Circuit Emulation Services (CES) and Local Loop Emulation Services (LLES). A typical VRC profile encompasses options for all sub-rates within one or more VRC standard or proprietary variable rate codec. The output of a rate determination algorithm (RDA), commonly part of variable rate codec, is fed into present AAL2 inter-working function (IWF).

Abstract: Multilayer switching device and associated technique enables simultaneous wire-speed routing at OSI layer 3, wire-speed switching at layer 2, and support multiple interfaces at layer 1. Implementation may be embodied using one or more integrated circuits (ASIC), RISC processor, and software, thereby providing wire-speed performance on interfaces, in various operational modes.

Abstract: Methods and systems are disclosed for eliminating a phase transient of a controlled frequency oscillator, caused by replacing a first reference signal by a second reference signal when the first reference signal becomes corrupted or otherwise unavailable, and for running a controlled frequency oscillator in a frequency-controlled holdover mode. The contradictory requirements of using a relatively low-cost controlled frequency oscillator tunable over a relatively wide frequency range and achieving high stability of its frequency in holdover mode are satisfied.

Abstract: Methods and systems are disclosed for eliminating a phase transient of a controlled frequency oscillator caused by replacing a first reference signal by a second reference signal when the first reference signal becomes corrupted or otherwise unavailable, and for running a controlled frequency oscillator in a frequency-controlled holdover mode. The contradictory requirements of using a relatively low-cost controlled frequency oscillator tunable over a relatively wide frequency range and achieving high stability of its frequency in holdover mode are satisfied.

Abstract: Round-robin arbitration circuit selects in clock cycle channel contending for arbitration; each arbitrated channel having channel number in sequence of channel numbers. Channel is designated as currently arbitrated; designated channel having designated number. Channels are masked from arbitration with designated channel, such that designated and unmasked channels are arbitrated to select channel. Channels having numbers sequenced after designated number are masked from arbitration, and channels having, numbers sequenced earlier than designated are also masked from arbitration. During subsequent cycle, designated channel is shifted to next channel in sequence of channel numbers by incrementing designated number. When designated number is last in sequence, designated channel is shifted to next having first number in sequence.

Abstract: An inter-processor communication system for a multi-processor environment wherein each processor has an associated processor system controller comprising an inter-processor communication registers (IPC Comm Reg). The IPC Comm Reg further comprising a response command register (CMD1 Reg), a non-response command register (CMD2 Reg), and a response register (RSP Reg). During inter-processor communication, the IPC Comm Reg of an initiating processor is coupled to the IPC Comm Reg of a target processor via the IPC bus so that data can be transmitted and one or more of a set of control flags of the target IPC Comm Reg is cleared or set in response to a write or read operation. In the inter-processor communication method for communication between multiple processors the initiating processor system controller coupled to an initiating processor detects the state of a set of status control flags of an initiating IPC Comm Reg associated with that initiating processor.

Abstract: Reactive congestion control in an asynchronous transfer mode (ATM) network where the network is formed by the interconnection of nodes each including a forward path for transfer of information from source to destination through the network and a return path for returning congestion control signals. Each source includes a modifiable issue rate unit which issues forward information signals at different rates for virtual channels in response to the presence and absence of congestion signals received on the return path.

Abstract: Asynchronous Transfer Mode Local Area Network (ATM LAN). The ATM LAN is implemented as a set of MAC entities which share a common group address space for the purposes of establishing multicast connections. Each station has one or more ATM MAC entities per physical connection to an ATM network. The network ATM LAN service provides the station with ATM LAN configuration information needed for ATM MAC operation. Included in this information is the number of ATM LANs the network has configured for that station.

Abstract: Reactive congestion control in an asynchronous transfer mode (ATM) network where the network is formed by the interconnection of nodes each including a forward path for transfer of information from source to destination through the network and a return path for returning congestion control signals. Each source includes a modifiable issue rate unit which issues forward information signals at different rates for virtual channels in response to the presence and absence of congestion signals received on the return path. When congestion occurs, for example, a queue exceeds a threshold, a request is made to send congestion signals, in the form of backward explicit congestion notification (BECN) cells, back to the sources of the virtual channels currently submitting traffic to the queue. On receipt of a BECN cell on a particular virtual channel, a source reduces it transmission rate for the indicated virtual channel.

Abstract: Asynchronous Transfer Mode Local Area Network (ATM LAN). The ATM LAN is implemented as a set of MAC entities which share a common group address space for the purposes of establishing multicast connections. Each station has one or more ATM MAC entities per physical connection to an ATM network. The network ATM LAN service provides the station with ATM LAN configuration information needed for ATM MAC operation. Included in this information is the number of ATM LANs the network has configured for that station.

Abstract: A self-routing switching element in a packet switch functions in a packet synchronous mode in which a plurality of the incoming packet signals are switched by the switching element concurrently during a common time period. For each incoming packet signal received during the common time period, the switching element control includes detector circuitry to detect that one of the inputs has an incoming packet signals for transmission to one of the outputs, includes determining circuitry for determining if the one of the output modules will accept the incoming packet signals, and includes enable circuitry, responsive to the determining circuitry, for enabling the acceptance of the incoming packet signal by the output module for transmission to the output. The control is distributed throughout the switching element in output modules, one module for each output from the switching element.

Abstract: A communication unit for concurrently processing cells in an asynchronous transfer mode (ATM) network. Packets are segmented into a plurality of cells concurrently for a plurality of channels for transmission over the (ATM) network. Cells received from the ATM network are reassembled concurrently for the plurality of channels. Pipelined processing units are employed for segmentation and for reassembly each having logic control, control memory, and data memory. The segmentation unit control memory stores two-dimensional queues with first dimension rate queues for queueing descriptors for cells of different channels having cells to be transmitted and with second dimension channel queues for each channel having a cell descriptor in the rate queue.

Abstract: A self-routing switching element in a packet switch functions in a packet synchronous mode in which a plurality of the incoming packet signals are switched by the switching element concurrently during a common time period. For each incoming packet signal received during the common time period, the switching element detects that one of the inputs has an incoming packet signal for transmission to one of the outputs, determines if the one of the output modules will accept the incoming packet signals, and responsive to the determination, enables the acceptance of the incoming packet signal by the output module for transmission to the output. The control circuitry is distributed throughout the switching element in output modules, one module for each output from the switching element.