Enhancing TCP performance in IP fast reroute
Minjing Mao, Zheng Wen, Kwan Lawrence Yeung · 2012
IP fast reroute (IPFRR) mechanisms are efficient in providing protection against link or router failure by invoking locally determined backup paths. But in the presence of a transient network failure, the path oscillates between backup and original paths, causing frequent packet out-of-order arrivals at a TCP receiver. Duplicate acknowledgments (DUP_ACKs) generated by the receiver will then trigger unnecessary TCP congestion control at the sender. In this paper, we propose a novel yet simple algorithm called duplicate acknowledgement suppression (DAS) for enhancing the TCP performance in the presence of IPFRR. DAS only requires a minor modification to the TCP implementation at the receiver side while leaving the sender intact. The key idea is to use the time-to-live field of an out-of-order packet to infer the cause of its out-of-order arrival. If that is deemed due to a transient network failure, no DUP_ACK will be generated. Simulation results show that our DAS algorithm yields noticeable goodput improvement.