Transmission Control Protocol (TCP) is considered one of the most important protocol in the internet. An important mechanism in TCP is the congestion control mechanism which controls TCP sending rate & makes TCP react to congestion signals. Now-a-days, TCP may work in n/w with some links that have lossy nature (ex. wireless network). TCP treats all packet losses if they due to congestion. TCP reduces sending rate aggressively when there are transmission errors in an uncongested network.