Abstract: Embodiments of a circuit, a buffered crosspoint switch that includes the circuit and a computer system that includes the switch are described. In this circuit and switch, deep crosspoint buffers are replaced with smaller distributed buffers. This modification reduces the cost of the switch and improves the scaling properties of the architecture.

Abstract: Apparatus and methods for real-time traffic classification based on off-line determined traffic classification rules are provided. Traces of real traffic are obtained and subjected to statistical analysis. The statistical analysis identifies the multidimensional domain space of characteristic traffic parameters. Classification rules associated with the identified domains are derived and provided to traffic classification points for real-time traffic classification. Traffic classification points, typically edge network nodes, sample packets in aggregate streams with a predetermined probability. Statistical information regarding the sampled flows is tracked in a table, the number of time a flow was sampled providing a probabilistic measure of the flow's duration before the flow terminates. The table entries, which predominantly track high bandwidth flows, are subjected to the classification rules for real-time classification of the sampled flows.

Abstract: A system that includes a first buffer and a second buffer, wherein the first buffer and the second buffer are connected to the same input, wherein a size of the first buffer is defined by a distance of the first buffer from the input and a transfer rate of data, wherein a size of the second buffer is defined by a distance of the second buffer from the input and the transfer rate of data, and wherein the distance between the first buffer and the input is different from the distance between the second buffer and the input.

Abstract: A system that includes a first buffer and a second buffer, wherein the first buffer and the second buffer are connected to the same input, wherein a size of the first buffer is defined by a distance of the first buffer from the input and a transfer rate of data, wherein a size of the second buffer is defined by a distance of the second buffer from the input and the transfer rate of data, and wherein the distance between the first buffer and the input is different from the distance between the second buffer and the input.

Abstract: A Weighted Random Early Detection (WRED) algorithm is described. The WRED algorithm provides fairness to responsive TCP and non-responsive UDP traffic at a buffer of a communications system. Because TCP traffic is responsive to congestion occurrences while UDP traffic is not, without controls, UDP will monopolize the buffer bandwidth. This invention solves the problem by applying congestion control alogrithms to TCP and UDP traffic separately. Discard thresholds for UDP traffic are dynamically modified in a manner that limits UDP traffic to a provisioned percentage of the buffer's available bandwidth, while a traditional WRED algorithm is applied to TCP traffic.

Abstract: A method and apparatus for scheduling and servicing events using a calendar structure is described. In accordance with one preferred embodiment of the present invention, a calendar structure is provided to implement work-conserving methods (for example, queuing, such as fair queuing, or, as one specific example, weighted fair queuing (WFQ)). Such a calendar structure preferably provides two slots per tier and uses a temporal pointer based on virtual time. In accordance with another preferred embodiment of the present invention, a calendar structure is provided to implement shaping of flows of information. Such a calendar structure preferably provides one slot per tier and uses a temporal pointer based on real time. For scheduling, a preferred occurrence time at which an event is preferred to occur is calculated.

Abstract: The sharing of forwarding states between multiple traffic paths is described. There is described a method for establishing a data traffic path in a communication network from a first node towards a second node. The method includes searching a set of pre-existing forwarding states for a pre-existing forwarding state associated with the first node for defining the traffic path from the first node towards the second node. If the pre-existing forwarding state for defining the traffic path cannot be found in the set of pre-existing forwarding states, then a new forwarding state for defining the traffic path from the first node towards the second node is generated the new forwarding state is used to establish the traffic path from the first node towards the second node. An apparatus implementing the method is described. The sharing of forwarding states as described may be used in MPLS enabled networks.

Abstract: A switch contains a first semiconductor die, which is configured to receive signals on a plurality of input ports and to output the signals on a plurality of output ports. The first semiconductor die is further configured to selectively couple the signals between the input and output ports using a plurality of switching elements in accordance with a set of control signals, which correspond to a configuration of the switch. During this process, a plurality of proximity connectors, proximate to a surface of the semiconductor die, are configured to communicate the signals by capacitive coupling.

Abstract: Embodiments of a scheduler for a switch, where the switch is configured to couple input ports to output ports are described. During operation, the scheduler may determine a schedule based on a group of requests, associated with multiple data streams, that are received for the output ports of the switch, where the schedule matches input ports to output ports of the switch for a given data cell time. Note that the schedule may be determined using an arbitration technique during a time interval. Moreover, the scheduler may assign an additional request, which was received at a time that precedes a current time by less than the time interval, to a portion of the switch which is available in the schedule, thereby reducing a latency of the scheduler.

Abstract: Embodiments of the present invention provide a system that schedules the transfer of cells in a switch. The system starts by receiving a set of cells to be transferred from a set of inputs of the switch to a set of outputs of the switch. The system includes S subschedulers, wherein each subscheduler processes N scheduling waves in sequence to generate a conflict-free transfer schedule for a given time slot for a matrix of transfer elements in the switch. The system then operates the subschedulers in parallel to generate S transfer schedules to transfer the cells from the set of inputs of the switch to the set of outputs of the switch during S time slots.

Abstract: Embodiments of the present invention provide a system that transfers data between the components in the computer system through a switch. In these embodiments, the switch includes multiple switch chips which are coupled together and are configured to collectively function as a switch. During operation, each switch chip, receives cells from the subset of the set of inputs and selectively transfers each of the cells to at least one output of the subset of the set of outputs coupled to the switch chip or of the subset of the set of outputs coupled to the other switch chips.

Abstract: A switch contains a first semiconductor die, which is configured to receive signals on a plurality of input ports and to output the signals on a plurality of output ports. The first semiconductor die is further configured to selectively couple the signals between the input and output ports using a plurality of switching elements in accordance with a set of control signals, which correspond to a configuration of the switch. During this process, a plurality of proximity connectors, proximate to a surface of the semiconductor die, are configured to communicate the signals by capacitive coupling.

Abstract: Apparatus and methods for real-time traffic classification based on off-line determined traffic classification rules are provided. Traces of real traffic are obtained and subjected to statistical analysis. The statistical analysis identifies domain the a multidimensional space of characteristic traffic parameters. Classification rules associated with the identified domains are derived and provided to traffic classification points for real-time traffic classification. Traffic classification points, typically edge network nodes, sample packets in aggregate streams with a predetermined probability. Statistical information regarding the sampled flows is tracked in a table, the number of time a flow was sampled providing a probabilistic measure of the flow's duration before the flow terminates. The table entries, which predominantly track high bandwidth flows, are subjected to the classification rules for real-time classification of the sampled flows.

Abstract: The sharing of forwarding states between multiple traffic paths is described. There is a described a method for establishing a data traffic path in a communication network from a first node towards a second node. The method includes searching a set of pre-existing forwarding states for a pre-existing forwarding state associated with the first node for defining the traffic path from the first node towards the second node. If the pre-existing forwarding state for defining the traffic path cannot be found in the set of pre-existing forwarding states, then a new forwarding state for defining the traffic path from the first node towards the second node is generated the new forwarding state is used to establish the traffic path from the first node towards the second node. An apparatus implementing the method is described. The sharing of forwarding states as described may be used in MPLS enabled networks.

Abstract: A packet switching node architecture is described in accordance with which multiple packets queued in input queues are considered in selecting packets to be forwarded via idle output ports. Considering multiple queued packets reduces the probability that an output port remains idle and increases the probability that each input queue is serviced despite forwarding of packets being blocked by contention. Also described are processes for enqueuing packets into, and dequeuing packets from, input queues, each input queue having associated therewith a multitude of head-of-line registers pointing to a corresponding sequence of head-of-line queue entries. Enqueuing ensures that the correct head-of-line registers point, in sequence, to a sequence of head-of-line queue entries. Servicing each input queue removes queue entries from the sequence, and dequeuing ensures the resequencing of the head-of-line pointers.

Abstract: A Weighted Random Early Detection (WRED) algorithm is described. The WRED algorithm provides fairness to responsive TCP and non-responsive UDP traffic at a buffer of a communications system. Because TCP traffic is responsive to congestion occurrences while UDP traffic is not, without controls, UDP will monopolize the buffer bandwidth. This invention solves the problem by applying congestion control alogrithms to TCP and UDP traffic separately. Discard thresholds for UDP traffic are dynamically modified in a manner that limits UDP traffic to a provisioned percentage of the buffer's available bandwidth, while a traditional WRED algorithm is applied to TCP traffic.

Abstract: At telecommunications switches and routers, RED (random early packet discard) uses the queue depth to determine whether to keep or discard each packet as it arrives at a queue. This is done by determining a discard probability P(colour), which is dependent on the average depth of the queue, and comparing the discard probability to a random number. The implementation of RED requires calculating the average depth of the queue to which RED is being applied. In calculating average queue depth, a weight is introduced. The value of the weight affects the amount of weighting that the previous average queue depth is given in relation to the current queue depth in calculating the new average queue depth. The invention uses a plurality of weights, depending on the status of the queue so that RED produces better discard operation. In a two-weight scheme, a smaller weight is used for an increasing queue depth and a larger one is used for a decreasing queue depth.

Abstract: A method and apparatus for scheduling and servicing events using a calendar structure is described. In accordance with one preferred embodiment of the present invention, a calendar structure is provided to implement work-conserving methods (for example, queuing, such as fair queuing, or, as one specific example, weighted fair queuing (WFQ)). Such a calendar structure preferably provides two slots per tier and uses a temporal pointer based on virtual time. In accordance with another preferred embodiment of the present invention, a calendar structure is provided to implement shaping of flows of information. Such a calendar structure preferably provides one slot per tier and uses a temporal pointer based on real time. For scheduling, a preferred occurrence time at which an event is preferred to occur is calculated.