Nortel Networks Corporation

Nxp Usa, Inc.

Ciena Corporation

Bernard Marchand

John Frank Pillar

Bernard Francois St-Denis

John F Pillar

Jacob Guttman

Sameh Rabie

Marc Leclair

Pierre Miller

Sitaram Patro

Michael Kardonik

Bernard St Denis

Peter W Newton

Mark A Schellhorn

Eric Englert

Benjamin B Nieh

A data processing system can comprise a first module having a workspace and configured to execute a task that can request access to a frame in a system memory, a queue manager configured to store a frame descriptor which identifies the frame in the system memory, and a memory access engine coupled to the first module and the queue manager. The memory access engine copies requested segments of the frame to the workspace and has a working frame unit to store a segment handle identifying a location and size of each requested segment copied to the workspace of the first module. The memory access engine tracks history of a requested segment by updating the working frame unit when the requested segment in the workspace is modified by the executing task.

Systems and methods for frame presentation and modification in a networking environment

A method and apparatus are provided for computing a CRC value for a data stream packet with a modified portion and an unmodified portion extending a distance to the end of the data stream packet by computing a first CRC value from the unmodified portion, computing a second CRC value from the modified portion, adjusting the second CRC value based on a shift length equal to the distance of the unmodified portion to compute a perspective shifted second CRC value by using a fixed number of distance lookup table operations, and generating an updated CRC value from the first CRC value and perspective shifted second CRC value, thereby avoiding recalculating a complete CRC value based on an entirety of the data stream packet.

Method of offloading cyclic redundancy check on portions of a packet

In Asynchronous Transfer Mode (ATM) communications networks, certain congestion control features, such as Partial Packet Discard (PPD) and Early Packet Discard (EPD), operate on ATM cells that have been segmented from ATM Adaptation Layer #5 (AAL5) frames (packets). AAL5 frames are automatically detected by observing transitions of an indicator in the ATM cell header unique to AAL5 traffic. Automatic detection of AAL5 traffic allows enablement of packet-aware cell discarding techniques such as PPD and EPD on a Virtual Channel Connection (VCC) basis, whether in a switch for a VCC or for a Virtual Path Connection (VPC) to which the VCC belongs.

Method and apparatus for auto detection of AAL5 type frames for VCC and VPC switches

A system and method for extending the reach of a data communication channel using flow control interception devices is described. The method decreases the latency-induced reduction in the data throughput and permits data transmission at subrates through the data communication channel. The method includes transmitting a data frame from a sending device. The data frame is transmitted through the data communication channel if a flow control signal is not asserted. The data frame is buffered if the flow control signal is asserted. The buffered data frame is transmitted through the data communication channel in response the flow control signal changing to an asserted state. The method also includes receiving the transmitted data frame from the data communication channel and transmitting the received data frame to a receiving device if the receiving device is available to process the data frame. If the receiving device is unavailable, the received data frame is buffered until the receiving device becomes available to process the buffered data frame.

Method and system for extending the reach of a data communication channel using a flow control interception device

In Asynchronous Transfer Mode (ATM) communications networks, certain congestion control features, such as Partial Packet Discard (PPD) and Early Packet Discard (EPD), operate on ATM cells that have been segmented from ATM Adaptation Layer &num;5 (AAL5) frames (packets). AAL5 frames are automatically detected by observing transitions of an indicator in the ATM cell header unique to AAL5 traffic. Automatic detection of AAL5 traffic allows enablement of packet-aware cell discarding techniques such as PPD and EPD on a Virtual Channel Connection (VCC) basis, whether in a switch for a VCC or for a Virtual Path Connection (VPC) to which the VCC belongs.

Scheduler methods and apparatus utilize a weight limited FIFO (WLF) method to provide weighted per-connection queuing while maximizing preservation of cell arrival order, thus minimizing additional cell delay variation (CDV) added during scheduling. The invention minimizes additional CDV of a connection until the connection exceeds its fair share of resource utilization.

Scheduler implementing weighted fair queuing by a weight limited first in-first out methodology

Inter-class schedulers for digital link systems provide high efficiency utilization of limited bandwidth by employing queuing techniques referred to as Statistical Priority Guarantee Queuing (SPGQ) and Generic Cell-Rate Algorithm Priority Guarantee Queuing (GCRA-PGQ). SPGQ &ldquo;elevates&rdquo; the priority of otherwise low-priority classes under prescribed circumstances in accordance with a statistical process. The SPGQ scheduler determines whether a number within a range produced by a uniform random number generator lies within a sub-range proportional to the programmed statistical guarantee for a given class. If the number lies within the sub-range associated with a given class, then the priority of that class is elevated to a higher priority when both are eligible to transmit. The GCRA-PGQ scheduler operates as a strict priority mechanism until a class requires bandwidth in excess of a GCRA &ldquo;window&rdquo; or threshold for that class. When that occurs, the service priority of that class is temporarily lowered.

Inter-class schedulers utilizing statistical priority guaranteed queuing and generic cell-rate algorithm priority guaranteed queuing

In Asynchronous Transfer Mode (ATM) communications networks, certain congestion control features, such as Partial Packet Discard (PPD) and Early Packet Discard (EPD), operate on ATM cells that have been segmented from ATM Adaptation Layer &num;5 (AAL5) frames (packets). AAL5 frames are automatically detected by observing transitions of an indicator in the ATM cell header unique to AAL5 traffic. Automatic detection of AAL5 traffic allows enablement of packet discard techniques such as PPD and EPD.

Method and apparatus for auto detection of AAL5 type frames

In an ATM communication system, a source transmitting in accordance with an Available Bit Rate service category must be policed to ensure that the cells are transmitted at a rate within the cell rate specified by the network at any given time. The usage parameter control system can only store a limited number of pending cell transmission rates to be enforced, and must make approximations by discarding certain stored pending cell transmission rates in order to make room for new cell transmission rates. This invention is directed towards a method for selecting which stored cell rates to discard that allows less cheating room in the cell rate enforcement than does the prior art, and that does not over-police.

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Cantley, Canada

Bernard Marchand