TCP k-SACK: A simple protocol to improve performance over lossy links

Abstract

We propose k-SACK, a TCP variant that has considerably improved throughput characteristics over lossy links. A k-SACK source does not consider every packet loss as an indication of congestion. It uses the Selective Acknowledgement option to estimate a parameter lookahead-loss, which is used in congestion detection. Our results demonstrate that k-SACK maintains a steady performance in a non-lossy environment while showing considerable performance improvement over paths spanning lossy links. Throughput gains of more than 90% are observed over links with packet loss rates of the order of 5%. We show that when k-SACK is used over wireline internet links, it does not harm the existing TCP variants significantly. k-SACK is simple to implement and does not involve any additional overheads.