61 results about "Head-of-line blocking" patented technology

The packet-buffering system and method of the present invention enables communication devices incorporating a full-mesh architecture to achieve bandwidth aggregation levels ordinarily associated with partial-mesh architectures. The packet-buffering invention uses a hierarchical memory structure having first and second packet-buffers to buffer packets between the input and output ports of the communication device. The received packets are organized by output port and priority level in the first packet buffer, which operates at the aggregate network rate of the communication device. The packets are then funneled to second packet buffers, having corresponding priority and output port assignments, at less than the aggregate network rate and which exhibit buffer depths that exceed that of the first packet buffer. The resulting hierarchical output-queued, packet-buffering system enables a communication system that exhibits a high degree of differentiated services with bandwidth guarantees and at high aggregation levels without experiencing head-of-line blocking.

An enhanced Peripheral Component Interconnect Express (PCIe) switch eliminates or reduces head-of-line blocking for memory reads initiated by peripheral endpoint devices. A memory-read request packet from a first peripheral endpoint device is intercepted by the enhanced PCIe switch, which generates a series of substitute request packets to the root complex and memory. The same requestor ID is used in all packets, but the original tag is replaced with a sequence of substitute tags in the substitute packets. The switch receives a sequence of reply packets with memory-read data, replaces substitute tags with original tags, and sends the reply packets to the peripheral endpoint device. Substitute request packets for different peripheral endpoint devices are alternately sent from the switch to the root complex to prevent head-of-line blocking by one peripheral endpoint device. The amount of data in each substitute request packet is smaller than the original requests to reduce blocking latencies.

Methods, systems, and computer program products for killing prioritized packets in multiple queues using time-to-live values to prevent head-of-line blocking. In one example, a method for scheduling prioritized packets in queuing system includes receiving a plurality of packets having a plurality of different priorities. The method can also include assigning the packets to the queues, wherein at least some of the queues include packets of a plurality of different priorities. In addition, the method can include assigning a first time-to-live (TTL) value to a first packet in a first queue. The method can also include altering the first TTL value of the first packet in response to a second packet of a second queue being scheduled. Further, the method can include discarding the first packet in response to the first TTL value having a predetermined relationship with respect to a predetermined value.

The present invention describes a system and method of improving packet forwarding throughput in a router by reducing head of line blocking. In one embodiment of the present invention, incoming packets are stored in a packet reorder buffer. The packets are reordered for forwarding while maintaining the order of packets in a distinct flow. Packets belonging to a distinct flow require to be forwarded in the order that the router receives them. Packets from different flows are reordered such that their forwarding order can be different than the order in which they were received. Packets from the same flow are sent out in the same order as the router receives them.

A method for preventing head of line blocking in an Ethernet system. In one embodiment, a network interface detects whether there is traffic flow congestion between the network interface and a data processing unit such as a CPU or other peripheral. If yes, the network interface communicates the congestion status to its attached Ethernet switch. In another aspect of the invention, the Ethernet switch then stops serving the congested port or queue, and informs a switch from which the traffic flow causing the congestion originates. In a further aspect, the originating switch then reduces bandwidth for the traffic flow causing the congestion. In a still further aspect, the originating switch can take the bandwidth that it acquired because of reducing the congesting traffic flow, and use it to increase bandwidth for other traffic flow.

To avoid packet out-of-sequence problems, while providing good load balancing, each input port of a switch monitors the outstanding number of packets for each flow group. If there is an outstanding packet in the switch fabric, the following packets of the same flow group should follow the same path. If there is no outstanding packet of the same flow group in the switch fabric, the (first, and therefore subsequent) packets of the flow can choose a less congested path to improve load balancing performance without causing an out-of-sequence problem. To avoid HOL blocking without requiring too many queues, an input module may include two stages of buffers. The first buffer stage may be a virtual output queue (VOQ) and second buffer stage may be a virtual path queue (VPQ). At the first stage, the packets may be stored at the VOQs, and the HOL packet of each VOQ may be sent to the VPQ. By allowing each VOQ to send at most one packet to VPQ, HOL blocking can be mitigated dramatically.

An Ethernet switch for preventing head of line blocking by passing an Ethernet packet carrying congestion status information among Ethernet switches over the Ethernet. When a port of an Ethernet switch is congested, the switch informs other Ethernet switches by broadcasting to other switches over the Ethernet an Ethernet packet indicating that the port is congested. If another Ethernet switch finds that one of its traffic classes is destined to the congested port, this switch drops packets of that traffic flow until receiving an Ethernet packet indicating that the congestion is alleviated.

A method is disclosed for maintaining a table of recent accesses for each port for use in predicting whether a request for data from a source device is likely to be sent to a high speed or low speed destination device. The table of recent accesses lists every source device attached to that port and the speed of the destination device with the most recent access to each source device. When an OPN primitive is received at the source port, the source device is identified and used with the table of recent accesses to predict whether the destination device is likely to be high speed or low speed, and ultimately whether to send data from the source device or reject the request.

A method, computer program product, and a data processing system for posting and retrieving WQEs to a shared receive queue in a manner that alleviates head-of-line blocking issues is provided. The present invention provides a shared receive queue and a posting routine for allowing non-sequential work request postings in the shared receive queue. Additionally, a fetch routine is provided for non-sequential fetching of work queue elements from the shared receive queue.

Systems, methods and software useful for overcoming network congestion problems including head-of-line blocking issues and other network congestion problems. In certain aspects, flow control mechanisms implemented in a switch device or other network device manage buffer and system level resources using a scheduler to control the amount of data requested from a local SAN fabric. Switches and other network devices configured according to the present invention monitor each individual SCSI task, and are configured to apply flow control measures to each active session when buffering resources become scarce, such as when buffering data for a slower-speed WAN link or TCP / IP based interconnects of any speed.

A head of line (HOL) blocking count value, which is directly proportional to the committed traffic load for traffic flow through an output port within a multi-stage switch mesh, is computed for a path by adding the values associated with all output ports within the path. In selecting a route, all paths from the source to the destination are identified and sorted by head of line blocking count value. Rather than selecting a path based on traffic load, the path having the lowest head of line blocking count value and sufficient capacity for the requested traffic is selected, with selection between paths having equal head of line blocking count values being made based on traffic load.

The invention discloses an all-node virtual-channel network-on-chip ring topology data exchange method. N switching nodes form a ring topology structure, N-1 virtual channels stored and arranged in parallel in each switching node correspond to the data of N-1 addresses of a previous node respectively, the virtual channels, corresponding to a certain target address node, of all the nodes form a virtual ring and all the data which are sent to the target node are sent by the virtual ring; and when an input FIFO module and the virtual channels send the data to the next node simultaneously, one path of the data is selected to be sent to a physical channel according to priority configuration and another path is fed back as a block signal, the next node feeds a signal back to the previous node when receiving the data and the virtual channel having the data are selected for transmission through switching-over when the feedback signal which represents the blockage is received. The invention also provides a ring topology data exchange system. The method and the system can effectively solve the problem of head-of-line blocking formed by all the nodes together and improve the communication efficiency.

Aspects of the present disclosure provide various apparatuses and methods of reordering DRB flow packets using an in-band solution to reduce delay due to data packet buffering in head-of-line blocking scenarios across multiple DRB flows. When a packet of a flow is lost or not received, other flows carried in the same DRB can forward later received packets without waiting for the missing packet to be retransmitted and received.

The invention relates to a data caching method of a fibre channel switch, comprising the following steps: step 81, the input port of a fibre channel (FC) switch is always in a state for monitoring whether FC data arrive at the input port, and the input port immediately sends a data caching request to the FC switch when the fact that FC data arrive is accurately detected; and step 82, when the input port sends the data caching request, the FC switch receives the data caching request, distributes a buffer for FC data in the buffer of the input port immediately, and stores the FC data in a designated buffer. The invention has the beneficial effects that during the process that FC data of the same input port are transmitted to different output ports, the phenomenon of head of line (HOL) blocking does not occur, and data overflow does not occur under the condition that the buffering reaches the controlled cached flow.

The invention discloses a buffering device which comprises at least one internal conversion unit and at least one basic buffering device. The internal conversion unit at least comprises two input ends and two output ends. The internal conversion unit is connected with the basic buffering device in close way at intervals through one input end of the two input ends and one output end of the two output ends. The other input end of the internal conversion unit receives light waves; the internal conversion unit outputs the light waves according to a first control signal and the basic buffering device is used for buffering the light waves from the internal conversion unit. Meanwhile, the invention further provides a network node and a regulating method. By employing the technical proposal of the invention, the scale of the network node is small, thus being easy for practice, reducing loss rate of data packets as well as avoiding blocking of head of line at the same time.

The invention raises the high efficiency cell dispatching algorithm based on paralleled buffer exchange structure and uses paralleled buffer structure to eliminate the blockage of traffic. The invention consists of cell input, paralleling buffer, interbedded section switch system, cell output and data processor.

The invention provides a message control method and network equipment. The method includes the following steps: detecting a message flow that causes a congestion state change; generating a congestionisolation message, wherein the congestion isolation message is used for changing the priority of messages in the message flow, and the congestion isolation message includes description information ofthe message flow; and sending the congestion isolation message to at least one node. By adopting the method, the network equipment and the like provided by the application, when the congestion state changes, the message flow causing the congestion state change can be identified, and other nodes can be notified to change the priority of the messages in the message flow without affecting the transmission of other message flows, so that the packet loss caused by congestion can be avoided, the occurrence of head-of-line blocking caused by non-congestion isolation can also be avoided to a great extent, and congestion diffusion can be avoided.

An Ethernet switch for preventing head of line blocking by passing an Ethernet packet carrying congestion status information among Ethernet switches over the Ethernet. When a port of an Ethernet switch is congested, the switch informs other Ethernet switches by broadcasting to other switches over the Ethernet an Ethernet packet indicating that the port is congested. If another Ethernet switch finds that one of its traffic classes is destined to the congested port, this switch drops packets of that traffic flow until receiving an Ethernet packet indicating that the congestion is alleviated.

A method is disclosed for maintaining a table of recent accesses for each port for use in predicting whether a request for data from a source device is likely to be sent to a high speed or low speed destination device. The table of recent accesses lists every source device attached to that port and the speed of the destination device with the most recent access to each source device. When an OPN primitive is received at the source port, the source device is identified and used with the table of recent accesses to predict whether the destination device is likely to be high speed or low speed, and ultimately whether to send data from the source device or reject the request.

The invention discloses a packet scheduling method based on probability retransmission in a wireless network. By the packet scheduling method, two factors comprising a link status and a queue jamming condition are considered when the scheduling right is set; the link status is determined by setting estimation factors on queues; on the aspect of probability retransmission, the specific queue jamming condition is considered; and a probability retransmission mechanism is proposed in a whole scheduling process, so that the problem of queue head jamming is solved. Moreover, by a scheduling algorithm, the queues which are failed to be sent previously are subjected to packet compensation, so that fairness is guaranteed. Queue data packets to be transmitted can be scheduled preferentially under the condition that the probability retransmission mechanism is used; because scheduling is performed under the condition that the queues of a base station are considered, data packet accumulation pressure at a bottleneck junction is relieved. By the packet scheduling method, research on a wireless network scheduling method has a wide application prospect.

Aspects disclosed in the detailed description include head-of-line blocking (HOLB) mitigation in communication devices. Output queues employed by a communication device for transmitting data are susceptible to HOLB. In this regard, in one aspect, a queue monitoring logic is configured to detect HOLB by measuring and comparing a depth(s) of an output queue(s) against a queue-overflow threshold. If the depth(s) of the output queue(s) exceeds the queue-overflow threshold, a queue weight(s) of a corresponding input queue(s) is decreased to reduce data flow into the output queue(s), thus mitigating the HOLB in the output queue(s). In another aspect, the queue monitoring logic is configured to detect queue depletion by comparing the depth(s) of the output queue(s) against a queue-depletion threshold. By mitigating the HOLB and the data starvation in the output queue(s), it is possible to optimize the output queue(s) to achieve higher throughput and data integrity with lower power consumption.

The invention relates to the technical field of electronic communication, and specifically to a method for preventing head-of-line blocking (HOL). The SDN-based method for preventing head-of-line blocking is applied to a SDN network comprising a plurality of switches and comprises the steps as follows: step 1, switches sense the state of an output port according to a set sensing method and report an HOL event to a SDN controller when the output port enters a head-of-line blocking state; step 2, the SDN controller calculates a forward path of the HOL event according to the HOL event so as to obtain an entrance switch and a corresponding input port; step 3, the SDN controller issues OF information to the input port; step 4, the input port drops a message causing the HOL event or limits the speed of the message causing the HOL event after receiving the OF information. By adopting an SDN framework, the method provided by the invention directly limits the message at the source so as to prevent the impact and influence to the whole SDN network to achieve the whole network defense for preventing head-of-line blocking.

A self-routing data switching system is disclosed. The data switching system includes a plurality of repetitive switching matrix planes, each of which is electrically connected between a less number of input terminals and a larger number of output terminals, thereby reducing the head-of-line blocking effect. Each switching matrix plane includes a switching element array interconnected between the input ports and the output ports for determining whether the data packet from an input port can be transmitted to a designated output port. The data switching system further includes a plurality of pre-processors to manage the input timing of data packets into the switching matrix array in order to avoid output conflict.

A method, computer program product, and a data processing system for posting and retrieving WQEs to a shared receive queue in a manner that alleviates head-of-line blocking issues is provided. The present invention provides a shared receive queue and a posting routine for allowing non-sequential work request postings in the shared receive queue. Additionally, a fetch routine is provided for non-sequential fetching of work queue elements from the shared receive queue.