Transmission Control Protocol’s Initial Congestion Window for Web Latency Reduction and Speedy Flows

Enem Theophilus Aniemeka

Transmission Control Protocol’s Initial Congestion Window for Web Latency Reduction and Speedy Flows

Keywords : Web Latency, Speedy Flows, TCP, Protocol, Congestion


Transmission Control Protocol (TCP) is a connection-oriented protocol which was designed to provide a reliable transfer of packet data across the Internet. As a result of the increased usage of the Internet, it became very necessary to increase the Internet’s initial congestion window (ICW). The problem of TCP was that its flow control algorithm in use was not suitable for short-lived links. Moreover, the slow start of the TCP prevented the optimal performance of the network from being attained, because the Internet web connection time tends to be very short. This causes the Slow Start phase to close; thereby making the ICW to adversely affect the number of round trip times (RTT) a Hypertext Transfer Protocol (HTTP) request/response requires. This study aimed at developing an initial congestion window for the TCP to enhance web latency reduction and speedy flows. This study developed a TCP congestion window model that determined the effect of the increase in congestion window size on the latency of Web requests for links with various RTT, Bandwidth (BW) and Bandwidth-delay product, so as to reduce the latency. A non-TCP congestion control algorithm on a Router was developed to improve the efficiency of a retransmission timer. Optimum Network Engineering Tools (OPNET 17.5) was used as the simulation tool for modeling of the ICW for TCP, while the implementation of algorithm was done using Microsoft Visual C++. The experiment employed a topology with a client-server connected to the router and an IP Cloud with a Digital Subscriber Line (DSL) link transmitting at 1.5MB/sec. Packets of various data sizes were transmitted while varying the ICW values. The methodology used demonstrated the ICW for TCP on a web content application. Also, a non-TCP congestion control algorithm was implemented on the router to optimize the retransmission timer and make the acknowledgement of request to be faster in order to reduce latency and increase speedy flows of traffic on the web. The result showed that the developed TCP model in varying the congestion window size from 2 to 48 was achieved. The modified Random Early Detection (RED) algorithms were able to reduce the transmission timer and also increase the congestion window size. Hence, the result showed that the RTT, throughput and web latency of windows 8/8.1 gave the best result compared to other operating systems (OS). The packet loss reduced to 18 bytes and the RTT was reduced to 10ms at TCP congestion window of 32. Hence, the TCP congestion window was increased to 32 segments.


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