Zero Queueing Flow Control and Applications

Zero Queueing Flow Control (ZQFC) is a new credit-based flow control method for ATM networks. The receiving node of such a flow-controlled link will have zero queue-occupancy in the steady state. ZQFC uses both link and VC flow control simultaneously over the link to implement the required rate adaptation for achieving zero queueing. Because of its zero queueing property, ZQFC is able to solve a head-of-the-line blocking problem that may arise when multiple VCs share the same receiver buffer in implementing their flow control. ZQFC works well with TCP traffic. When there is any queue buildup associated with a TCP connection in a shared buffer, ZQFC will identify the connection and take steps to reduce its arrival rate at the buffer. This will allow many TCP connections to share the buffer efficiently and fairly. It makes sense to deploy ZQFC for just a single link where performance improvement is critical. Simulations using real-life TCP code have demonstrated these advantages of ZQFC.