Modeling and Simulation of Out-of-Order Impact in TCP Protocol

Abstract

Abstract-The Internet provides a powerful, cost effective, reliable, and survivable communication over the world for different services like e-commerce, finance, education, military, and so on. The Internet has been rapidly increased; it has been growing at unprecedented rates. As the Internet become huge, its network performance becomes subjected to a lot of problems that decrease the communication performance like congestion, interference, reordering and so on.In this paper, we focus on measuring the impact of packets and ACKs reordering on the performance of TCP variants namely TCP Reno, TCP New Reno, TCP SACK, and TCP Vegas, we also analyze the performance of these protocols when their duplicate acknowledgement threshold (Dupthresh) values are increased in order to prevent false fast retransmissions and unnecessary Congestion Window Size (CWND) reductions. Index Terms-TCP, out-of-order, NS-2, TCP Reno, TCP newReno, TCP SACK, TCP Vegas. I. INTRODUCTIONThe Internet communication is managed by set of protocols grouped by several layers, these protocols and layers construct the communications framework model or suite, TCP/IP suite one of the most common of all network protocol suites. TCP/IP is a hierarchical protocol made up of interactive layers (Fig. 1). Application layer are placed at the top of TCP / IP stack [1], it include many protocols, such as (FTP, HTTP, SMTP and so on) for application communication. The transport layer follows the application layer. TCP/IP makes available two distinct transport layer protocols to the application layer: Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). In our thesis, we depend Transmission Control Protocol (TCP) which is the most commonly used protocol in the Internet, because it is used for so many application protocols such as HTTP, POP, SMTP, etc. to Manuscript received November 12, 2014; revised June 14, 2015. S. Kadry is with American University of the Middle East, Kuwait (e-mail: skadry@gmail.com).A. E. Al-Issa was with Arts Sciences and Technology University, Lebanon (e-mail: eng.aliedan@yahoo.com).transfer data reliably between the source and destination. TCP provides reliable connection between the sender and the receiver by using sequence number for each packet and ACKs that confirm the delivery of the packet to the destination, TCP uses several techniques and algorithms to regulate the transmission rate at which the sender must send such as congestion control and flow control and etc.The recent researches [2], [3] appear that the occurrence of packet reordering on the network is not pathological behavior. Bennett et al. [4] had intended that reordering is highly prevalent on many links. The results of their study [4] indicate that the probability of a session, running through the US MAE-East exchange, experiencing packet reordering was over 90%. Intuitively, Bennett et al. referenced that the reason for the large proportion of flows experiencing reordering was the presence of parallelism on the routes taken by the packets flowing throug...

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“…More troubling is the fact that all other out-of-order data packets that might arrive on the receiver's side on time are not delivered to the player's side of the application by TCP, until the re-sent packet arrives [10]. As a consequence, these out-of-order packets can miss their deadlines too.…”