System and method for managing storage requests issued from multiple sources in a distributed storage system utilizes different queues at a host computer in the distributed storage system to place different classes of storage requests for access to a virtual storage area network. The storage requests in the queues are processed using a fair scheduling algorithm. For each queue, when the storage requests in the queue exceeds a threshold, a backpressure signal is generated and transmitted to at least one source for a class of storage requests queued in one of the queues corresponding to that backpressure signal to delay issuance of new storage requests of that class of storage requests.

An apparatus for load balancing based on available bandwidth estimation includes a bandwidth module configured to determine for a networking device a first available bandwidth estimate for a first egress port and a second available bandwidth estimate for a second egress port, a load balancing module configured to select the first egress port as a selected port in response to determining that the first available bandwidth estimate of the first egress port exceeds a predetermined level and to select the second egress port as the selected port in response to determining that the available bandwidth estimate of the first egress port does not exceed the predetermined level and that the second available bandwidth estimate of the second egress port exceeds the predetermined level, and a transmission module configured to transmit a packet from the selected port. A method and network switching device work similarly to the apparatus.

Back-pressure control in a telecommunications network, in which a method of back-pressure control in a transport network is provided. A buffer state of a buffer is monitored. A condition indicative of back-pressure is also determined in response to a change of the buffer state passing a predetermined limit. In response to determining the condition indicative of back-pressure, a back-pressure notification message is created and, subsequently, transmitted to at least one second network node.

A data transmission method includes obtaining dequeue information that indicates a queue which requests to output data in a communications device and a target data volume that is output from each queue at a time, and the communications device manages the target data volume based on a burst value, reading, based on the queue, a sub-packet descriptor (PD) that is obtained by segmenting the first PD. the sub-PD includes target description information indicating a target data packet, the first PD includes first description information indicating a first data packet set including the target data packet, the first data packet set and the sub-PD are stored in a packet cache including a dynamic random access memory (DRAM), the first PD is stored in a control cache including a static random access memory (SRAM), and determining, the target data packet based on the sub-PD, and sending the target data packet.

Roughly described: a network interface device has an interface. The interface is coupled to first network interface device circuitry, host interface circuitry and host offload circuitry. The host interface circuitry is configured to interface to a host device and has a scheduler configured to schedule providing and/or receiving of data to/from the host device. The interface is configured to allow at least one of: data to be provided to said host interface circuitry from at least one of said first network device interface circuitry and said host offload circuitry; and data to be provided from said host interface circuitry to at least one of said first network interface device circuitry and said host offload circuitry.

Back-pressure control in a telecommunications network, in which a method of back-pressure control in a transport network is provided. A buffer state of a buffer is monitored. A condition indicative of back-pressure is also determined in response to a change of the buffer state passing a predetermined limit. In response to determining the condition indicative of back-pressure, a back-pressure notification message is created and, subsequently, transmitted to at least one second network node.

A switching system includes a port extender device coupled to a central switching device. Packets processed by the central switching device are forwarded to the port extender device and enqueued in ones of a plurality of egress queues in the port extender device for transmission of the packets via the front ports of the port extender device. Respective egress queues in the port extender device have a queue depth that is less than a queue depth of corresponding respective egress queues in the central switching device. A flow control message indicative of congestion in a particular egress queue of the port extender device is generated and transmitted to the central switch device to control transmission of packets from the central switching device to the particular egress queue of the port extender device.

Some embodiments provide a method for a hardware forwarding element. The method adds a received packet to a buffer. The method determines whether adding the packet to the buffer causes the buffer to pass one of multiple flow control thresholds, each of which corresponds to a different packet priority. When adding the packet to the buffer causes the buffer to pass a particular flow control threshold corresponding to a particular priority, the method generates a flow control message for the particular priority.

In some embodiments, an apparatus includes a flow control module configured to receive a first data packet from an output queue of a stage of a multi-stage switch at a first rate when an available capacity of the output queue crosses a first threshold. The flow control module is configured to receive a second data packet from the output queue of the stage of the multi-stage switch at a second rate when the available capacity of the output queue crosses a second threshold. The flow control module configured to send a flow control signal to an edge device of the multi-stage switch from which the first data packet or the second data packet entered the multi-stage switch.

Roughly described: a network interface device has an interface. The interface is coupled to first network interface device circuitry, host interface circuitry and host offload circuitry. The host interface circuitry is configured to interface to a host device and has a scheduler configured to schedule providing and/or receiving of data to/from the host device. The interface is configured to allow at least one of: data to be provided to said host interface circuitry from at least one of said first network device interface circuitry and said host offload circuitry; and data to be provided from said host interface circuitry to at least one of said first network interface device circuitry and said host offload circuitry.