Abstract: A network interface is disclosed for enabling remote programmed I/O to be carried out in a “lossy” network (one in which packets may be dropped). The network interface: (1) receives a plurality of memory transaction messages (MTM's); (2) determines that they are destined for a particular remote node; (3) determines a transaction type for each MTM; (4) composes, for each MTM, a network packet to encapsulate at least a portion of that MTM; (5) assigns a priority to each network packet based upon the transaction type of the MTM that it is encapsulating; (6) sends the network packets into a lossy network destined for the remote node; and (7) ensures that at least a subset of the network packets are received by the remote node in a proper sequence. By doing this, the network interface makes it possible to carry out remote programmed I/O, even across a lossy network.

Abstract: A mechanism is disclosed for enabling load balancing to be achieved in a loop-free switching path, reverse path learning network, such as an Ethernet network. The network is divided into a plurality of virtual networks, with each virtual network providing a different path through the network. When it comes time to send a set of information through the network, one of the plurality of virtual networks, and hence, one of the plurality of paths, is selected. The set of information is then updated to indicate the selected virtual network, and sent into the network to be transported along the selected path. With multiple paths, and with the ability to select between the multiple paths, it is possible to balance the load imposed on the multiple paths.

Abstract: A network interface is disclosed for enabling remote programmed I/O to be carried out in a “lossy” network (one in which packets may be dropped). The network interface: (1) receives a plurality of memory transaction messages (MTM's); (2) determines that they are destined for a particular remote node; (3) determines a transaction type for each MTM; (4) composes, for each MTM, a network packet to encapsulate at least a portion of that MTM; (5) assigns a priority to each network packet based upon the transaction type of the MTM that it is encapsulating; (6) sends the network packets into a lossy network destined for the remote node; and (7) ensures that at least a subset of the network packets are received by the remote node in a proper sequence. By doing this, the network interface makes it possible to carry out remote programmed I/O, even across a lossy network.

Abstract: A mechanism is disclosed for enabling load balancing to be achieved in a network. In one implementation, load balancing is implemented on a “per flow” basis. At the time that a new flow starts, a path is selected. Packets associated with the flow are thereafter sent along that particular path. As the packets associated with the flow are forwarded along the particular path, a congestion metric is determined for the particular path as well as for a set of one or more other paths. Based at least partially upon the congestion metrics, a determination is made as to whether the flow should be moved. If so, then the flow is moved to an alternate path. By determining the congestion metrics for the multiple paths, and by moving the flow in response, it is possible to adapt to changing traffic conditions to keep the loads on the paths relatively balanced.

Abstract: A mechanism is disclosed for determining a congestion metric for a path in a network. In one implementation, a congestion metric for a path includes one or more latency values and one or more latency variation values. A latency value for a path may be determined by exchanging latency packets with another component. For example, to determine the latency for a particular path, a first component may send a latency request packet to a second component via the particular path. In response, the second component may send a latency response packet back to the first component. Based upon timestamp information in the latency response packet, the latency on the particular path may be determined. From a plurality of such latencies, a latency variation may be determined. Taken individually or together, the latency value(s) and the latency variation value(s) provide an indication of how congested the particular path currently is.

Abstract: A mechanism is disclosed for enabling load balancing to be achieved in a loop-free switching path, reverse path learning network, such as an Ethernet network. The network is divided into a plurality of virtual networks, with each virtual network providing a different path through the network from a source node to a destination node. When it comes time to send a set of information from the source node to the destination node, one of the plurality of virtual networks, and hence, one of the plurality of paths, is selected. The set of information is then updated to indicate the selected virtual network, and sent into the network to be transported to the destination node along the selected path. With multiple paths, and with the ability to select between the multiple paths, it is possible to balance the load imposed on the multiple paths.

Abstract: A network of spine switches and leaf switches is disclosed wherein the spine switches and leaf switches are coupled using a simplified interconnect made up of multiple signal carrying media (SCM's). In the simplified interconnect, “virtual” links are used rather than physical links to couple the leaf switches to the spine switches. The virtual links are implemented using wavelength division multiplexing. By implementing virtual links, the network achieves the same connectivity as that provided by a Clos network without the complex interconnect that is typically required in a Clos network.