Third-party flow control

Flow control is critical to the efficient operation of Internet service providers network equipment. In particular, the ability to effectively shape traffic can reduce cost and improve overall customer satisfaction. While such traffic shaping is typically performed by an inline traffic shaper, there are a number of practical cases in which such an inline approach is not feasible. In particular, an inline traffic shaper may reduce reliability or simply be against ISP policy. In these cases third-party flow control is required. Third-party flow control allows the shaper to see all traffic and to inject new traffic into the network. However, it does not allow the shaper to remove or modify existing network data. Within these limitations we study two techniques for flow control, triple-ACK duplication and zero-window-size acknowledgement. We provide analytical justification for why these techniques are promising. In addition, we demonstrate, via simulation, that the zero-window-size technique can reduce bandwidth consumption by 40%, while the triple-ACK duplication can reduce it by up to 85%. These techniques thus offer the possibility for significant flow-control capabilities by a third-party traffic shaper.