Abstract: A method for incorporating a queuing device as a lossless processing stage in a network device in a communications network, comprising: monitoring a depth of a queue in the queuing device, the queue for receiving packets from an upstream device within the network device, the queuing device acting as a discard point by discarding packets when the queue is full; and, if the depth passes a predetermined threshold, sending a message to the upstream device to reduce a rate at which packets are sent to the queuing device to prevent the queue from filling and thereby preventing packet discarding and loss by the queuing device.

Abstract: The invention provides a system and method of controlling timing of release of traffic for a communication switch. The traffic originates from at least one source, is directed to a common ingress point of the switch and is directed to a common egress point in the switch. The egress point has a maximum egress transmission rate. The traffic has at least one datastream. Each datastream has a requested transmission rate. The method comprises, for each datastream, establishing a maximum cell release rate such that a sum of each of the maximum cell release rate does not exceed the maximum egress transmission rate and utilizing the maximum cell release rate to govern release of local traffic in the datastream from the ingress point.

Abstract: A method and apparatus are provided for maintaining access control lists (ACLs) within TCAM on a line card in a data packet router, the rules being applied to incoming data packets. Each interface may be associated with multiple ACLs, and multiple interfaces may be associated with single shared ACLs. The shared ACLs include rules applicable to more than one interface. Other ACLs are specific to a particular interface. When searching for a rule to apply to an incoming data packet, the filter searches both the specific ACL and the shared ACLs associated with the interface over which the data packet arrived. Using the shared ACLs, duplication of common rules is reduced, thereby reducing the total number of rules stored on the line card and saving memory storage space. The invention is also applicable to sets of rules other than ACLs.

Abstract: The packet rate limiting method and system is used for detecting and blocking the effects of DoS attacks on IP networks. The method uses an ACL counter that stores an action parameter in the first 3 most significant bits and uses 13 bits as a packet counter. A rate limit is enforced by setting the packet counter to an initial value, and resetting this value at given intervals of time. The action parameter enables the ACL to accept or deny packets based on this rate limit. If the number of packets in the incoming flow saturates the packet counter before the reset time, the packets are denied access to the network until the counter is next reset. The denied packets may be just discarded or may be extracted for further examination.

Abstract: A method for identifying faulty modules within telecommunication devices, such as ATM switches, involves generating and attaching verification codes, such as a CRC or checksum codes, to data packets at an upstream location determining the integrity of the verification codes at each of multiple downstream location within a telecommunication device; and signaling an error condition where a corrupted data packet has been detected. A verification code may be written to a field of a data packet which is not used while the packet is in transit through the telecommunication device.

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: The backpressure flow control mechanism is widely used in telecommunications network. Actions of the flow control scheme are not instantaneous in that latency always exists between action and reaction, resulting in a flow control round trip time. This flow control round trip time causes ambiguity in determining the amount of traffic in transit. The invention monitors the amount of traffic which is on the way toward the queue during the past period of the round trip time, thus eliminating the ambiguity. A more precise control of traffic flow is possible, realizing reduction of storage space in the queue by one half. In one embodiment, the invention keeps a historical record of flow control signals sent back during the most recent flow control round trip time.

Abstract: A method for incorporating a queuing device as a lossless processing stage in a network device in a communications network, comprising: monitoring a depth of a queue in the queuing device, the queue for receiving packets from an upstream device within the network device, the queuing device acting as a discard point by discarding packets when the queue is full; and, if the depth passes a predetermined threshold, sending a message to the upstream device to reduce a rate at which packets are sent to the queuing device to prevent the queue from filling and thereby preventing packet discarding and loss by the queuing device.

Abstract: A method and apparatus for sending packets from traffic flows to queues in a network element is provided. Each traffic flow has a packet size parameter indicating a sizing constraint for its packets. The method includes the step of grouping the traffic flows into groups utilizing the packet size parameter of each traffic flow. The method further includes the step of sending packets only from traffic flows of one group to at least one designated queue. Traffic flows of the one group are identified utilizing the packet size parameter of each traffic flow.

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: The packet rate limiting method and system is used for detecting and blocking the effects of DoS attacks on IP networks. The method uses an ACL counter that stores an action parameter in the first 3 most significant bits and uses 13 bits as a packet counter. A rate limit is enforced by setting the packet counter to an initial value, and resetting this value at given intervals of time. The action parameter enables the ACL to accept or deny packets based on this rate limit. If the number of packets in the incoming flow saturates the packet counter before the reset time, the packets are denied access to the network until the counter is next reset. The denied packets may be just discarded or may be extracted for further examination.

Abstract: A method and apparatus are provided for maintaining access control lists (ACLs) within TCAM on a line card in a data packet router, the rules being applied to incoming data packets. Each interface may be associated with multiple ACLs, and multiple interfaces may be associated with single shared ACLs. The shared ACLs include rules applicable to more than one interface. Other ACLs are specific to a particular interface. When searching for a rule to apply to an incoming data packet, the filter searches both the specific ACL and the shared ACLs associated with the interface over which the data packet arrived. Using the shared ACLs, duplication of common rules is reduced, thereby reducing the total number of rules stored on the line card and saving memory storage space. The invention is also applicable to sets of rules other than ACLs.

Abstract: The backpressure flow control mechanism is widely used in telecommunications network. Actions of the flow control scheme are not instantaneous in that latency always exists between action and reaction, resulting in a flow control round trip time. This flow control round trip time causes ambiguity in determining the amount of traffic in transit. The invention monitors the amount of traffic which is on the way toward the queue during the past period of the round trip time, thus eliminating the ambiguity. A more precise control of traffic flow is possible, realizing reduction of storage space in the queue by one half. In one embodiment, the invention keeps a historical record of flow control signals sent back during the most recent flow control round trip time.

Abstract: A method for identifying faulty modules within telecommunication devices, such as ATM switches, involves generating and attaching verification codes, such as a CRC or checksum codes, to data packets at an upstream location determining the integrity of the verification codes at each of multiple downstream location within a telecommunication device; and signaling an error condition where a corrupted data packet has been detected. A verification code may be written to a field of a data packet which is not used while the packet is in transit through the telecommunication device.

Abstract: Apparatus and method for implementing virtual path aggregation (VPA) of underlying virtual connections at a switching node of a connection based communications network. A multi-service traffic shaping module (MTSM) at the switch implements algorithms to aggregate the VC and VP connections onto the aggregate VP by representing an aggregate VP as a plurality of circular linked lists or loops and assigning each VC connection to a link or element in the circular linked lists according to traffic descriptors. Weighting factors are used as between loops to dynamically select the next loop to service. Once this loop is chosen, the next VC to be serviced is identified by examining the circular linked list structure.

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: A method for identifying faulty modules within telecommunication devices, such as ATM switches, involves generating and attaching verification codes, such as CRC or checksum codes, to data packets, such as ATM cells, at an upstream location, determining the integrity of the verification codes at each of multiple downstream location within a telecommunication device; and signaling an error condition where a corrupted data packet has been detected. A verification code may be written to a filed of a data packet which is not used while the ATM cell is in transit through the telecommunication device, thereby identifying a faulty module device without adversely affecting throughput.

Abstract: High-speed signaling pins are often at a premium in Field Programmable Gate Arrays and minimizing the number of high-speed signals crossing a midplane is desirable to simplify system design and improve reliability. The method disclosed herein provides a more pin-efficient high-speed data path interface with per-queue backpressure signaling than what is available in prior art, leading to reduced system design and manufacturing costs and improved perfonnance. The invention improves upon an industry standard protocol, the SPI 4.2 protocol, for high speed data transmission between switching system components by adding advanced functionality from a widely supported standards proposal, the CSIX level 2. In doing so, the invention offers a hybrid of the two interfaces that is more pin-efficient than either of them.

Abstract: The method described herein is a more efficient way to transmit non-user data over a SPI 4.2 interface. During single PHY mode, the transmission occurs between single ports, eliminating the need for a port address in the control word portion of the SPI 4.2 data word. Consequently, the address bits can be used to indicate the type of data being transmitted in single PHY mode, either user or non-user data. Since non-user data is transmitted periodically, the bandwidth granularity is improved by using bandwidth when required for the non-user data as opposed to dedicating bandwidth to it. The bandwidth granularity is reduced to remain within the specifications for any type of SPI 4.2 packet, including OC-192.

Abstract: A method for verifying the integrity of data payloads of ATM cells passing through a switching device involves computing a payload integrity verification code for the payload portion of an ATM cell. The payload integrity verification code may be generated according to any error detection or error correction scheme. Preferably, the payload integrity verification code is stored in a portion of the standard ATM cell header which is not used while the cell is passing through the switching device. Preferably the payload integrity verification code is stored in all, or a portion of, the virtual path identifier or virtual connection identifier fields. The invention allows for the immediate identification of cells having corrupted payload data. Different actions may be taken on the detection of errors in the ATM cell header and ATM cell payloads respectively.