Abstract: A network device may receive packets and may calculate, during a time interval, an arrival rate and a departure rate, of the packets, at one of multiple virtual output queues. The network device may calculate a current oversubscription factor based on the arrival rate and the departure rate, and may calculate a target oversubscription factor based on an average of previous oversubscription factors associated with the multiple virtual output queues. The network device may determine whether a difference exists between the target oversubscription factor and the current oversubscription factor and may calculate, when the difference exists, a scale factor based on the current oversubscription factor and the target oversubscription factor. The network device may calculate new scheduling weights based on prior scheduling weights and the scale factor, and may process packets received by the multiple virtual output queues based on the new scheduling weights.

Abstract: An apparatus for switching network traffic includes an ingress packet forwarding engine and an egress packet forwarding engine. The ingress packet forwarding engine is configured to determine, in response to receiving a network packet, an egress packet forwarding engine for outputting the network packet and enqueue the network packet in a virtual output queue. The egress packet forwarding engine is configured to output, in response to a first scheduling event and to the ingress packet forwarding engine, information indicating the network packet in the virtual output queue and that the network packet is to be enqueued at an output queue for an output port of the egress packet forwarding engine. The ingress packet forwarding engine is further configured to dequeue, in response to receiving the information, the network packet from the virtual output queue and enqueue the network packet to the output queue.

Abstract: A network device may receive packets and may calculate, during a time interval, an arrival rate and a departure rate, of the packets, at one of multiple virtual output queues. The network device may calculate a current oversubscription factor based on the arrival rate and the departure rate, and may calculate a target oversubscription factor based on an average of previous oversubscription factors associated with the multiple virtual output queues. The network device may determine whether a difference exists between the target oversubscription factor and the current oversubscription factor and may calculate, when the difference exists, a scale factor based on the current oversubscription factor and the target oversubscription factor. The network device may calculate new scheduling weights based on prior scheduling weights and the scale factor, and may process packets received by the multiple virtual output queues based on the new scheduling weights.

Abstract: A network device may receive packets and may calculate, during a time interval, an arrival rate and a departure rate, of the packets, at one of multiple virtual output queues. The network device may calculate a current oversubscription factor based on the arrival rate and the departure rate, and may calculate a target oversubscription factor based on an average of previous oversubscription factors associated with the multiple virtual output queues. The network device may determine whether a difference exists between the target oversubscription factor and the current oversubscription factor and may calculate, when the difference exists, a scale factor based on the current oversubscription factor and the target oversubscription factor. The network device may calculate new scheduling weights based on prior scheduling weights and the scale factor, and may process packets received by the multiple virtual output queues based on the new scheduling weights.

Abstract: An ingress fabric endpoint coupled to a switch fabric within a network device reorders packet flows based on congestion status. In one example, the ingress fabric endpoint receives packet flows for switching across the switch fabric. The ingress fabric endpoint assigns each packet for each packet flow to a fast path or a slow path for packet switching. The ingress fabric endpoint processes, to generate a stream of cells for switching across the switch fabric, packets from the fast path and the slow path to maintain a first-in-first-out ordering of the packets within each packet flow. The ingress fabric endpoint switches a packet of a first packet flow after switching a packet of a second packet flow despite receiving the packet of the first packet flow before the packet of the second packet flow.

Abstract: A network device may receive packets and may calculate, during a time interval, an arrival rate and a departure rate, of the packets, at one of multiple virtual output queues. The network device may calculate a current oversubscription factor based on the arrival rate and the departure rate, and may calculate a target oversubscription factor based on an average of previous oversubscription factors associated with the multiple virtual output queues. The network device may determine whether a difference exists between the target oversubscription factor and the current oversubscription factor and may calculate, when the difference exists, a scale factor based on the current oversubscription factor and the target oversubscription factor. The network device may calculate new scheduling weights based on prior scheduling weights and the scale factor, and may process packets received by the multiple virtual output queues based on the new scheduling weights.

Abstract: In general, techniques are described for facilitating balanced cell handling by fabric cores of a fabric plane for an internal device switch fabric. In some examples, a routing system includes a plurality of fabric endpoints and a switching fabric comprising a fabric plane to switch cells among the fabric endpoints. The fabric plane includes two fabric cores and one or more inter-core links connecting the fabric cores. Each fabric core selects an output port of the fabric core to which to route a received cell of the cells based on (i) an input port of the fabric core on which the received cell was received and (ii) a destination fabric endpoint for the received cell, at least a portion of the selected output ports being connected to the inter-core links, and switches the received cell to the selected output port.

Abstract: An apparatus for switching network traffic includes an ingress packet forwarding engine and an egress packet forwarding engine. The ingress packet forwarding engine is configured to determine, in response to receiving a network packet, an egress packet forwarding engine for outputting the network packet and enqueue the network packet in a virtual output queue. The egress packet forwarding engine is configured to output, in response to a first scheduling event and to the ingress packet forwarding engine, information indicating the network packet in the virtual output queue and that the network packet is to be enqueued at an output queue for an output port of the egress packet forwarding engine. The ingress packet forwarding engine is further configured to dequeue, in response to receiving the information, the network packet from the virtual output queue and enqueue the network packet to the output queue.

Abstract: A system and method for routing network packets. A switch fabric connects a plurality of forwarding units, including an egress forwarding unit and two or more ingress forwarding units, each ingress forwarding unit forwarding network packets to the egress forwarding unit via the switch fabric. The egress forwarding unit includes a scheduler and an output queue. Each ingress forwarding unit includes a Virtual Output Queue (VOQ) connected to the output queue and a VOQ manager. The scheduler receives time of arrival information for packet groups stored in the VOQs, determines, based on the time of arrival information for each packet group, a device resident time for each packet group, and discards the packet groups when the determined device resident time for the packet group is greater than a maximum resident time.

Abstract: An apparatus for switching network traffic includes an ingress packet forwarding engine and an egress packet forwarding engine. The ingress packet forwarding engine is configured to determine, in response to receiving a network packet, an egress packet forwarding engine for outputting the network packet and enqueue the network packet in a virtual output queue. The egress packet forwarding engine is configured to output, in response to a first scheduling event and to the ingress packet forwarding engine, information indicating the network packet in the virtual output queue and that the network packet is to be enqueued at an output queue for an output port of the egress packet forwarding engine. The ingress packet forwarding engine is further configured to dequeue, in response to receiving the information, the network packet from the virtual output queue and enqueue the network packet to the output queue.

Abstract: A network device includes a memory, a plurality of packet processors, a switch fabric coupling the plurality of processors, and processing circuitry. The processing circuitry is configured to receive a data stream to be transmitted on a switch fabric and determine a plurality of credit counts, each credit count being assigned to a respective subchannel of a plurality of subchannels. The packet processor is further configured to determine per-subchannel occupancy of the memory for the plurality of subchannels, select, based on the plurality of credit counts and the per-subchannel occupancy of the memory, a subchannel of the plurality of subchannels for transmitting a cell of a plurality of cells for the data stream, and output data for the cell to the memory for output by the selected subchannel.

Abstract: In general, techniques are described for facilitating balanced cell handling by fabric cores of a fabric plane for an internal device switch fabric. In some examples, a routing system includes a plurality of fabric endpoints and a switching fabric comprising a fabric plane to switch cells among the fabric endpoints. The fabric plane includes two fabric cores and one or more inter-core links connecting the fabric cores. Each fabric core selects an output port of the fabric core to which to route a received cell of the cells based on (i) an input port of the fabric core on which the received cell was received and (ii) a destination fabric endpoint for the received cell, at least a portion of the selected output ports being connected to the inter-core links, and switches the received cell to the selected output port.

Abstract: An ingress fabric endpoint coupled to a switch fabric within a network device reorders packet flows based on congestion status. In one example, the ingress fabric endpoint receives packet flows for switching across the switch fabric. The ingress fabric endpoint assigns each packet for each packet flow to a fast path or a slow path for packet switching. The ingress fabric endpoint processes, to generate a stream of cells for switching across the switch fabric, packets from the fast path and the slow path to maintain a first-in-first-out ordering of the packets within each packet flow. The ingress fabric endpoint switches a packet of a first packet flow after switching a packet of a second packet flow despite receiving the packet of the first packet flow before the packet of the second packet flow.

Abstract: An apparatus for switching network traffic includes an ingress packet forwarding engine and an egress packet forwarding engine. The ingress packet forwarding engine is configured to determine, in response to receiving a network packet, an egress packet forwarding engine for outputting the network packet and enqueue the network packet in a virtual output queue. The egress packet forwarding engine is configured to output, in response to a first scheduling event and to the ingress packet forwarding engine, information indicating the network packet in the virtual output queue and that the network packet is to be enqueued at an output queue for an output port of the egress packet forwarding engine. The ingress packet forwarding engine is further configured to dequeue, in response to receiving the information, the network packet from the virtual output queue and enqueue the network packet to the output queue.

Abstract: An ingress fabric endpoint coupled to a switch fabric within a network device reorders packet flows based on congestion status. In one example, the ingress fabric endpoint receives packet flows for switching across the switch fabric. The ingress fabric endpoint assigns each packet for each packet flow to a fast path or a slow path for packet switching. The ingress fabric endpoint processes, to generate a stream of cells for switching across the switch fabric, packets from the fast path and the slow path to maintain a first-in-first-out ordering of the packets within each packet flow. The ingress fabric endpoint switches a packet of a first packet flow after switching a packet of a second packet flow despite receiving the packet of the first packet flow before the packet of the second packet flow.

Abstract: A system and method for routing network packets. A switch fabric connects a plurality of forwarding units, including an egress forwarding unit and two or more ingress forwarding units, each ingress forwarding unit forwarding network packets to the egress forwarding unit via the switch fabric. The egress forwarding unit includes a scheduler and an output queue. Each ingress forwarding unit includes a Virtual Output Queue (VOQ) connected to the output queue and a VOQ manager. The scheduler receives time of arrival information for network packets stored in the VOQs, determines, based on the time of arrival information for each network packet, a device resident time for the network packets stored in the VOQs, and requests, from one of the VOQs and based on the device resident times, the network packet with the longest device resident time.

Abstract: An ingress fabric endpoint coupled to a switch fabric within a network device reorders packet flows based on congestion status. In one example, the ingress fabric endpoint receives packet flows for switching across the switch fabric. The ingress fabric endpoint assigns each packet for each packet flow to a fast path or a slow path for packet switching. The ingress fabric endpoint processes, to generate a stream of cells for switching across the switch fabric, packets from the fast path and the slow path to maintain a first-in-first-out ordering of the packets within each packet flow. The ingress fabric endpoint switches a packet of a first packet flow after switching a packet of a second packet flow despite receiving the packet of the first packet flow before the packet of the second packet flow.

Abstract: A system and method of transferring cells through a switch fabric having a shared memory crossbar switch, a plurality of cell receive blocks and a plurality of cell transmit blocks. The system determines, based on a number of cells queued up in respective output buffers in the cell transmit blocks, output buffers in the cell transmit blocks that can receive cells on a low latency path. The cells transferred include first cells that can be transferred on the low latency path and second cells that cannot be transferred via the low latency path. The first cells are transferred via a bypass mechanism in shared memory to the output buffers. The second cells are transferred by writing the second cells to shared memory, reading the second cells from shared memory and transferring the second cells read from shared memory to the output buffers in the cell transmit blocks.

Abstract: A system and method of transferring cells through a switch fabric having a shared memory crossbar switch, a plurality of cell receive blocks and a plurality of cell transmit blocks. The system determines, based on a number of cells queued up in respective output buffers in the cell transmit blocks, output buffers in the cell transmit blocks that can receive cells on a low latency path. The cells transferred include first cells that can be transferred on the low latency path and second cells that cannot be transferred via the low latency path. The first cells are transferred via a bypass mechanism in shared memory to the output buffers. The second cells are transferred by writing the second cells to shared memory, reading the second cells from shared memory and transferring the second cells read from shared memory to the output buffers in the cell transmit blocks.