An Jumpot Phuritatkul creator Erke, Tapio J. Chairperson Ahmed, Kazi Mohiuddin Examination Committee Kanchana Kanchanasut Examination Committee Asian Institute of Technology Scholarship donor National Electronics and Computer Technology Center (NECTEC), Thailand Scholarship donor text series technical report th Bangkok Asian Institute of Technology 1999 continuing eng 55 p. The congestion control of TCP over UBR has two main parts. These are TCP congestion window in TCP layer and special mechanisms to control ATM cells on UBR service such as dropping policies and buffer allocation. The UBR service supported by ATM networks does not provide explicit congestion control mechanisms and is intended to transport data traffic in general. The congestion control mechanisms operating at the cell level has been proposed to enhance the performance of UBR service. Congestion control in TCP relies on windows based protocol. A stream of data sent on a TCP connection is delivered reliably and in order at the destination. The performance of congestion control mechanisms in UBR service for TCP sources is investigated in this thesis work. SACK TCP has the highest performance but the implementation is very complex and it is necessary to be modified at both ends of sender and receiver to support UBR service. The New TCP achieves performance slightly less than SACK but it is simpler than SACK due to modification at only sender site. RED performs well in both static and dynamic traffic sources, especially in transient traffic. The use of the average queue size is essential in RED to give a tolerance for transient congestion. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Advanced Technologies Thesis (M.Eng.) - Asian Institute of Technology, 1999 TCP/IP (Computer network protocol) Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B12301 http://203.159.5.9/ait-thesis/detail.php?q=B12301 240300 20260818144302.0