Abstract
Transmission Control Protocol (TCP) is considered one of the most important protocols in the Internet. An important mechanism in TCP is the congestion control mechanism which controls TCP sending rate and makes TCP react to congestion signals. Nowadays in heteroge- neous networks, TCP may work in networks with some links that have lossy nature (wireless networks for example). TCP treats all packet loss as if they were due to congestion. Consequently, when used in networks that have lossy links, TCP reduces sending rate aggressively when there are transmission (non-congestion) errors in an uncongested network. In this paper we present different solutions to overcome the performance degradation problem TCP faces when working over lossy links. Many solutions have been proposed but we will concentrate on end-to-end so- lutions that require no help from the intermediate network.