Multi-Level Flow Control for Ethernet MAN Congestion

The patent segments the flow control mechanism into three distinct levels: port-level flow control (using standard 802.3x frames), board-level flow control (using self-defined board flow control frames), and channel-level flow control (using self-defined channel flow control frames). Each level operates independently with its own detection and feedback mechanisms, allowing comprehensive coverage without requiring complete redesign of the existing port-level mechanism.

The patent extends flow control from the traditional single dimension of port-level to multiple dimensions by adding board-level and channel-level control. This multi-dimensional approach allows flow control to operate at different hierarchical levels simultaneously, where each level monitors and controls traffic specific to its scope, thereby increasing adaptability without linearly increasing complexity.

The patent implements continuous feedback mechanisms at each level. The receiving end continuously monitors buffer status at port level, board level, and channel level, and sends corresponding flow control frames back to the sending end when congestion is detected. The sending end continuously checks for these feedback frames and adjusts transmission accordingly, creating a real-time closed-loop control system that responds dynamically to changing network conditions.

The patent uses buffer threshold detection to trigger flow control before actual congestion occurs. When buffer usage reaches a predefined threshold, flow control frames are sent immediately to prevent further data ingress, thereby avoiding packet loss and maintaining real-time performance. This preliminary action approach proactively manages traffic before problems arise.