Abstract: In some embodiments a switching device is disclosed that includes one or more ingress queues to queue data received from external sources while waiting to forward the data to one or more egress queues. The egress queues queue the data while waiting to transmit the data to external sources. The switching device also includes a switch fabric to provide connectivity between the one or more ingress queues and the one or more egress queues. The switching device further includes an ingress flow-control manager to monitor flow-control state of the one or more ingress queues, and to detect and recover from loss of ON flow-control messages. Other embodiments are otherwise disclosed herein.

Abstract: In general, in one aspect, the disclosure describes a multi-stage switch having a plurality of ingress switching modules to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal. The multi-stage switch further includes a core switching module operatively connected to receive the wavelength division multiplexed signal from the at least one ingress switch module and to switch the frames. The multi-stage switch additionally includes a plurality of egress switching modules to receive the wavelength division multiplexed signal from the core switch module and to transmit data. The multi-stage switch is capable of detecting faulty paths and transmitting data through fault-free paths.

Abstract: In general, in one aspect, the disclosure describes a multi-stage switch having at least one ingress switch module to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal. The multi-stage switch further includes a core switch module operatively connected to receive the wavelength division multiplexed signal from the at least one ingress switch module and to switch the frames. The multi-stage switch additionally includes at least one egress switch module to receive the wavelength division multiplexed signal from the core switch module and to transmit data. The at least one ingress switching module and the at least one egress switching module are capable of replicating multicast data packets.

Abstract: In general, in one aspect, the disclosure describes a multi-stage switch having at least one ingress switch module to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal. The multi-stage switch further includes a core switch module operatively connected to receive the wavelength division multiplexed signal from the at least one ingress switch module and to switch the frames. The multi-stage switch additionally includes at least one egress switch module to receive the wavelength division multiplexed signal from the core switch module and to transmit data.

Abstract: In general, in one aspect, the disclosure describes an apparatus that includes a plurality of flow controllable queues containing data to be transmitted. The queues are organized by flow. The apparatus also includes a plurality of destinations to receive data from the plurality of queues. The apparatus further includes a controller to continually maintain an aggregate count of data ready for transmission to the destinations and determine next queue to transmit data from based at least partially on the aggregate counts.

Abstract: In general, in one aspect, the disclosure describes an apparatus for selecting a queue from a plurality of queues. The apparatus includes a hierarchal queue occupancy device to indicate an occupancy status of the plurality of queues, a next queue selector to select a queue based on said hierarchal queue occupancy device and a most recently serviced queue, and a queue identification register to identify a most recently serviced queue.

Abstract: In general, in one aspect, the disclosure describes an apparatus capable to select a queue. The apparatus includes a queue occupancy device to indicate an occupancy status of the queues, a queue occupancy cache to record an update in occupancy status of a particular queue, a next queue selector to select a queue based on said queue occupancy device and a most recently serviced queue, and a queue identification register to identify a most recently serviced queue.

Abstract: In general, in one aspect, the disclosure describes a switching device that includes a segmentation unit to receive data packets of variable size and to store the data packets as segments. The data packets received having a length greater than a maximum segment length are divided into multiple segments. A plurality of queues associated with destinations store the segments. The switching device also includes a scheduler to generate a schedule including a data path from at least one queue to an associated destination. A framer aggregates a plurality of segments to form a frame. The frame has a maximum frame length and may contain segments associated with different data packets. The segments are retrieved from the at least one queue. The switching device further includes a transmitter to transmit the frame to the associated destination. The segments within the frame are transmitted together.

Abstract: A method is disclosed for efficiently determining exact loss rate, or a loss curve, for a traffic source transmitted at a specified rate. The loss curve of a traffic source characterizes the loss rate of the traffic stream as a function of the allocated buffer size for a given transmission rate. Utilization of loss curve characterization allows for optimal resource allocation for a given source within a packet network. The present invention provides a deterministic method for computing the loss curve of a traffic source, examples of which include multimedia streams, elementary video streams, and MPEG-2 transport streams. The present method exploits the piecewise linearity of the loss curve and computes only the points at which the slope of the loss curve changes. The method is memory efficient and executes rapidly, for instance, a loss curve for a two-hour elementary video stream was determined within eleven seconds on a conventional Sun Ultra-2™ workstation.

Abstract: In general, in one aspect, the disclosure describes a switching device that includes a segmentation unit to receive packets and divide packets having a length greater than a maximum segment length into multiple segments. A plurality of queues associated with a source and a destination stores the segments. A request generator generates requests that include external factors including amount of data contained in the queue and at least some subset of priority and age. A scheduler receives the requests and assigns the requests an internal priority based on the external factors. The scheduler processes the requests for the queues by internal priority in order to generate grants. A framer, responsive to the scheduler, aggregates a plurality of segments for the queues that received a grant to form a frame and to transmit the frame to an associated destination. The frame may contain segments associated with different packets.

Abstract: In general, in one aspect, the disclosure describes a switching device that includes a plurality of ingress ports to receive data from external sources and a plurality of egress ports to transmit data to external destinations. The switching device also includes a plurality of queues to store data waiting to be transmitted from a particular ingress port to a particular egress port. A request generator generates requests for permission to transmit data for the queues. A request indicates a cumulative amount of data contained in a respective queue. A switching matrix provides selective connectivity between the ingress ports and the egress ports. The switching device further includes a scheduler to receive the requests, generate grants based thereon, and configure the switching matrix. The scheduler incorporates a mechanism to periodically monitor its operating efficiency and perturb its internal state when its efficiency is below a certain desired level.

Abstract: In general, in one aspect, the disclosure describes a switching device that includes a plurality of ingress ports to receive data from external sources and a plurality of egress ports to transmit data to external destinations. The switching device also includes a plurality of queues to store data waiting to be transmitted from a particular ingress port to a particular egress port. A request generator generates requests for permission to transmit data for the queues. A request indicates a cumulative amount of data contained in a respective queue. A switching matrix provides selective connectivity between the ingress ports and the egress ports. The switching device further includes a scheduler to receive the requests, generate grants based thereon, and configure the switching matrix. The scheduler operates on a pipeline schedule and modifies the requests received to account for grants generated in current period or previous period not reflected in the queues.

Abstract: In general, in one aspect, the disclosure describes an apparatus that includes a plurality of flow controllable queues containing data to be transmitted. The queues are organized by flow. The apparatus also includes a plurality of destinations to receive data from the plurality of queues. The apparatus further includes a controller to continually maintain an aggregate count of data ready for transmission to the destinations and determine next queue to transmit data from based at least partially on the aggregate counts.

Abstract: In general, in one aspect, the disclosure describes a switching device that includes a plurality of ports. The ports operate at asymmetric speeds. The apparatus also includes a switching matrix to provide selective connectivity between the ports. The apparatus further includes a plurality of channels to connect the ports to the switching matrix. The number of channels associated with each port is determined by speed of the port.

Abstract: In general, in one aspect, the disclosure describes a flow control hub that includes a scoreboard memory device to maintain flow control status for a plurality of flows. Each of the flows is identified by an associated index. The apparatus also includes an address decoder to receive a flow control message and to determine an associated index based on the address portion. The apparatus further includes an updater to update the flow control status in said memory device based on the received flow control message.

Abstract: The resources required to support transmission of a traffic source, such as video or multimedia, over a packet-switched network are heavily dependent on the burstiness of the traffic source. The present invention provides methods for accurately and rapidly determining burstiness curves for traffic sources, such as elementary video and MPEG-2 transport streams. The described deterministic computation methods provide space and time efficiency in relation to the level of accuracy selected. The methods teach the exploitation of the piecewise linearity within the burstiness curves such that computations are only performed at points subject to slope change. The efficiency of the described methods suggest wide applicability to a range of traffic characterization situations, including QoS provisioning as well as real-time applications, such as TV distribution.

Abstract: In general, in one aspect, the disclosure describes an apparatus capable of queuing and de-queuing data stored in a plurality of queues. The apparatus includes a status storage device to track status for each of the plurality of queues, a status cache to track status for a subset of the plurality of queues that are undergoing processing, and a queuing engine to queue incoming data and de-queue outgoing data. The queuing engine receives and updates the status for the subset of the plurality of queues from the status cache and receives and updates the status for remaining queues from the status storage device.

Abstract: In general, in one aspect, the disclosure describes an apparatus that includes a transmission module to split a data segment into a plurality of data stripes and transmit each data stripe over an associated data channel. The plurality of data channels are organized into at least one group and each group has an associated parity channel to transmit a parity stripe generated based on the data stripes within the group. The apparatus also includes a reception module to receive the plurality of data stripes and the at least one parity stripe. The apparatus further includes a controller to control the operation of the apparatus.

Abstract: In general, in one aspect, the disclosure describes an apparatus capable to select a queue. The apparatus includes a queue occupancy device to indicate an occupancy status of the queues, a queue occupancy cache to record an update in occupancy status of a particular queue, a next queue selector to select a queue based on said queue occupancy device and a most recently serviced queue, and a queue identification register to identify a most recently serviced queue.

Abstract: In general, in one aspect, the disclosure describes an apparatus that includes a transmission module to split a data segment into a plurality of data stripes and transmit each data strip over an associated serial channel, a reception module to receive the plurality of data stripes over the associated serial channels and track a number of errors per channel, and a controller to deactivate a serial channel and reconfigure said transmission module and said reception module to utilize remaining data channels for striping data if the number of errors in the serial channel exceeds a threshold.