Network switch supporting rate-based and credit-based flow control mechanisms ona link-by-link basis

摘要

Network interface logic includes first logic executing a credit-based flow-control protocol (e.g., Quantum Flow Control or QFC) and second logic executing a rate-based flow control protocol (e.g. Explicit Rate or ER). The second logic transfers data cells between a network link and the first logic and inserts and extracts forward (FRM) and backward (BRM) flow-control/resource management (RM) cells. The second logic further (i) obtains cell buffer utilization information from the first logic, (ii) supplies transmission credits to the first logic based on rate information in BRM cells, (iii) induces the first logic to emit "dummy" RM cells when an RM cell is to be transmitted, and (iv) converts the dummy cells to either FRM or DRM cells for forwarding on the link. Rate information in the transmitted RM cells is calculated from the buffer utilization information and rate information in extracted BRM cells.