In today's Internet scenario, the current TCP has performed reasonably well. As the Internet has scaled up in load, speed, size and connectivity by the order of six over the past fifteen years, the TCP has consistently avoided severe congestion throughout this same period. Applications involving high performance computings such as bulk-data transfer, multimedia Web streaming, and computational grids demand high bandwidth. These applications usually operate over wide-area networks and, hence, performance over wide-area networks has become a critical issue. Future applications will need steady transfer rates in the order of gigabits per second to support collaborative work. TCP, which is the most widely used protocol, is expected to be used in these scenarios. It has been shown that TCP doesn't work well in this new environment, and several new TCP versions have been developed in recent years to address this issue. To date, there has not been a performance evaluation of various TCP protocols. In this thesis, various TCP versions 3/4 Tahoe, Reno, Newreno, Vegas, Westwood, Sack, Highspeed TCP, Scalable TCP 3/4 have been evaluated for their performance over high bandwidth delay product networks. It was found that the flow and congestion control mechanism used in TCP was unable to reach full utilization on high-speed links. Also discussed in this Thesis are fairness issues related to these new protocols with respect to themselves and with others.