BACKGROUND

Network overload, or as it is commonly called network congestion, happens as a result of collisions between flows exceeding the capacity of the network buffers. Transport protocols such as Transmission Control Protocol (TCP) are commonly used to control network congestion by adjusting the load offered to the network based on feedback from lost or marked packets.

Lossless Ethernet (e.g., data center bridging) refers to enhancements to the Ethernet protocol for use within datacenters to allow Ethernet to be used for storage and high-performance computing (e.g., clustering). These enhancements attempt to eliminate packet loss due to queue overflow and to allow bandwidth allocation on different links in the network. Current data center fabrics, such as Fiber Channel over Ethernet (FCoE) and Remote Direct Memory Access over Ethernet (RDMA), are sensitive to frame loss. Lossless Ethernet maintains feedback for TCP and RDMA using explicit congestion notification bits encoded within data packets rather than using packet discard. In some examples, congestion is the primary cause of loss and delay in such large scale, low-latency, lossless Ethernet datacenters. By coupling congestion notification (e.g., Explicit Congestion Notification (ECN), Quantized Congestion Notification (QCN), etc.) with priority-based flow control, lossless Ethernet prevents packet loss.

