Although there are two standard transport protocols, TCP and UDP, offering services in the Internet, the majority of the traffic over the Internet is TCP-based. TCP-based applications can react to packet losses; however, many performance problems have been recently observed in the Internet. To resolve these problems, several new TCP fast retransmit and fast recovery algorithms have been proposed. This article surveys state-of-the-art fast retransmit and fast recovery mechanisms of TCP to address the lost packet problem, and presents a description of some useful algorithms, design issues, advantages, and disadvantages. The objective of this article is fourfold: to provide an introduction to TCP protocol; to discuss problems degrading TCP retransmission performance in the present-day Internet; to describe some proposed transport protocols that solve a number of throughput issues; and finally, to gain new insight into these protocols and thereby suggest avenues for future research. Based on our taxonomy, existing fast retransmit and fast recovery schemes of transport protocols are described in this survey.
- Fast recovery
- Fast retransmit