Nortel Networks Corporation

Northern Telecom Limited

Ciena Corporation

Avaya Inc.

John Frank Pillar

Bernard Marchand

Bernard Francois St-Denis

Alan Charles Coady

Jonathan David Loewen

Jacob Guttman

Sameh Rabie

David James Evans

Scott Larrigan

Allen Lengacher

Sitaram Patro

Ra'ed Yousif Awdeh

Bernard St Denis

Deborah Ann Frischknecht

Gordon Kerr

Benjamin B Nieh

Eric Englert

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

In a stream processing node, a producer of properly ordered portions of a data stream, hereinafter referred to as substreams, is coupled to a stream fabric that is further coupled to a series of potential consumers for the data stream, one of the potential consumers being a content processing element. The producer outputs the substreams to a stream queue that is associated with the data stream within the stream fabric. Subsequently, a portion of the data within the stream queue is copied and analyzed by the content processing element which determines what further actions are to be taken with respect to the data within the particular stream queue. These actions could include copying a further portion of the data within the stream queue to the content processing element for further analysis; redirecting the data within the stream queue to another consumer of the data stream, such as another processing element or an interface with a packet switched network; modifying a portion of the data within the stream queue; and/or transferring a portion of the data within the stream queue to another stream queue.

Stream processing node

The invention provides a method and apparatus for policing a traffic flow in which a first stage of policing is performed on the traffic flow to produce a first stage conforming flow and a first stage violating flow. These two flows are then policed again in a second stage of policing, such that the first stage conforming flow can take advantage of a capacity allowed for the first stage violating flow which is unused by the first stage violating flow. In some embodiments, performing a first stage of policing involves associating each packet of the traffic flow with one of a plurality of sub-flows, policing at least one of the plurality of sub-flows individually to produce for each sub-flow a respective conforming sub-flow and a respective violating sub-flow. The conforming sub-flow(s) collectively are the first stage conforming flow. The violating sub-flows collectively are the first stage violating flow.

Multi-flow multi-level leaky bucket policer

A method and apparatus for searching for a character pattern within a data stream. A checksum is computed for one or more patterns for which the data stream will be searched. The patterns may be of the same length or they may be of different lengths. A shift register is used to sequentially parse through the data stream and compute the checksum of a series of bytes in the data stream. If the checksum of the bytes in the data stream that have been shifted into the register matches the checksum from one of the character patterns, then the character pattern corresponding to the checksum has been found. The system may search multiple character patterns simultaneously by using multiple checksum generators in parallel.

Method and apparatus for finding variable length data patterns within a data stream

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.

Dynamic generic cell rate algorithm for policing ABR traffic

Methods and systems consistent with the present invention store connection information in a memory of a node in a communications network such that the number of searches for retrieving the connection information is less than a predetermined probe threshold. The node includes a hash table and a connection table in the memory for storing and retrieving information associated with packets, frames, and/or cells in the communications network. Each entry in the hash table includes a connection identifier and, for example, a connection index, and is indexed according to a hash value based on the connection identifier. Each entry in the connection table includes connection state information that is indexed according to a connection index in the hash table. To store connection information in the memory, the node identifies in the hash table a first set of addresses that correspond to a first connection identifier. When the first set of addresses does not correspond to a free entry, the node randomly selects one of the first set of addresses, and identifies a second connection identifier in an entry at the randomly selected address. The node then inserts the second connection identifier at a free one of a second set of addresses corresponding to the second connection identifier and inserts the first connection identifier at the randomly selected address.

Method and system for storing and retrieving information in a communications node

An ATM network carries several categories of services, each having its own traffic characteristics and performance requirements. The ABR (available bit rate) service category is the only existing one suited for high-reliability data communications, such as file transfer, LAN emulation, etc. The invention relates to the control of ABR traffic flow in an ATM network, to quickly utilize the bandwidth left unused by higher priority service categories while minimizing ABR cell loss, and maintaining fairness among ABR connections. On each ABR connection, the source end system periodically sends RM (resource management) cells to the corresponding destination end system which loops them back to the source. The ATM network may instruct the ABR sources of the exact rates it can support by modifying a certain field in the RM cells. The invention relates to techniques of deriving the proper explicit cell rate for each ABR connection which can grow to a fair level even under special conditions.

Flow control mechanism of ABR traffic in ATM networks

The invention resides in the field of transferring data and other information from multiple asynchronous TDM channels across a synchronous interface in digital blocks of a preset length. Presently, transfer of data and timing information requires serial transmission of frame payload, qualified with clock and frame pulse indications. A separate set of these signals is required in both directions for each port or physical link. An interface of the invention permits data transfer in blocks which are uniquely identified for a specific port or links and the position of the block within the frame (if the transfer is one of framed data). The invention greatly reduces the number of required signals, thus enabling reduction of pin count requirements and an increase in the number of serviced ports.

Data transfer method and apparatus

A technique of processing multiple digital signal streams uses one instantiation of an algorithm with memory storage of the next state, to facilitate context switching. In one embodiment, the invention is applied to framing and mapping techniques, resulting in a low circuit count for implementation with excellent performance, when measured with the commonly accepted criteria.

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Nepean, Canada

John Frank Pillar