ANALYSIS OF PHANTOM : AN EFFICIENT FLOW CONTROL SCHEME FOR. TCP

Abstract

The end-to-end control mechanisms of TCP have always been a critical factor in ti robustness of the Internet. In the past few years, several new techniques for flow contra of TCP have been introduced. Some of these operate at the source end stations and son at the routers. In the former, if the network is observed to be not congested, the windo size is increased while if the network is observed to be congested, window size decreased. In the latter, when the router buffer overflows, some packets are dropper But both of these mechanisms suffer from unfair allocation and large queue buildups the router. This thesis discusses and analysis a simple and effective flow control algorithm calk Phantom [1].. The basic idea of Phantom is to keep a certain portion of the link capacil unused and to limit the rates of sessions sharing the link by the amount of unuse bandwidth on that link. The Phantom algorithm requires two simple modifications to ti existing TCP, i.e. Current rate (CR) calculation at the source and Maximum Allowed Ce Rate (MACR) calculation at the router. If the CR in the packet header is greater tha MACR at the router, packets corresponding to the source are dropped. But the Phantoi algorithm causes initial queue buildups. To reduce these queue buildups, we ha` proposed a modification to Phantom. It is shown that this modified version of Phantoi does reduce queue buildup and also improves fairness. We have done simulation of a TCP/IP network, to measure the performance of Phantoi algorithm compared to the TCP-Reno. The software is written in C++, and runs undh LINUX environment.