RR-TCP: A Reordering-Robust TCP with DSACK

TCP performs poorly on paths that reorder packets significantly, where it misinterprets out-of-order delivery as packet loss. The sender responds with a fast retransmit though no actual loss has occurred. These repeated false fast retransmits keep the sender’s window small, and severely degrade the throughput it attains. Requiring nearly in-order delivery needlessly restricts and complicates Internet routing systems and routers. Such beneficial systems as multi-path routing and parallel packet switches are difficult to deploy in a way that preserves ordering. Toward a more reordering-tolerant Internet architecture, we present enhancements to TCP that improve the protocol’s robustness to reordered and delayed packets. We extend the sender to detect and recover from false fast retransmits using DSACK information, and to avoid false fast retransmits proactively, by adaptively varying dupthresh. Our algorithm is the first that adaptively balances increasing dupthresh, to avoid fal...

• Type: Conference
• Year: 2003
• Where: ICNP
• Authors: Ming Zhang, Brad Karp, Sally Floyd, Larry L. Peterson
• Keywords: False Fast Retransmits, Fast Retransmits, ICNP 2003, Network Protocols, TCP’s RTO Estimator