Browsing by Author "Chan, Yi-Cheng"

Now showing 1 - 5 of 5

CODE TCP: A competitive delay-based TCP
(2010-06-01)
Chan, Yi-Cheng
;
Lin, Chia-Liang
;
Chan, Chia-Tai
;
Ho, Cheng-Yuan
;
資訊工程學系
TCP Vegas is a well-known delay-based congestion control mechanism. Studies have indicated that TCP Vegas outperforms TCP Reno in many aspects. However, Reno currently remains the most widely deployed TCP variant in the Internet. This is mainly because of the incompatibility of Vegas with Reno. The performance of Vegas is generally mediocre in environments where it coexists with Reno. Hence, there exists no incentive for operating systems to adopt Vegas as the default transport layer protocol. In this study, we propose a new variant of Vegas called COmpetitive DElay-based TCP (CODE TCP). This variant is compatible with Reno and it can obtain a fair share of network resources. CODE is a sender-sided modification and hence it can be implemented solely at the end host. Simulations and experiments confirm that CODE has better fairness characteristics in network environments in which it coexists with Reno while retaining the good features of Vegas. (C) 2010 Elsevier B.V. All rights reserved.
Fast retransmit and fast recovery schemes of transport protocols: A survey and taxonomy
(2008-04-24)
Ho, Cheng-Yuan
;
Chen, Yaw-Chung
;
Chan, Yi-Cheng
;
Ho, Cheng-Yun
;
資訊工程學系
Although there are two standard transport protocols, TCP and UDP, offering services in the Internet, the majority of the traffic over the Internet is TCP-based. TCP-based applications can react to packet losses; however, many performance problems have been recently observed in the Internet. To resolve these problems, several new TCP fast retransmit and fast recovery algorithms have been proposed. This article surveys state-of-the-art fast retransmit and fast recovery mechanisms of TCP to address the lost packet problem, and presents a description of some useful algorithms, design issues, advantages, and disadvantages. The objective of this article is fourfold: to provide an introduction to TCP protocol; to discuss problems degrading TCP retransmission performance in the present-day Internet; to describe some proposed transport protocols that solve a number of throughput issues; and finally, to gain new insight into these protocols and thereby suggest avenues for future research. Based on our taxonomy, existing fast retransmit and fast recovery schemes of transport protocols are described in this survey. (C) 2008 Elsevier B.V. All rights reserved.
Gallop-Vegas: An enhanced slow-start mechanism for TCP Vegas
(2006-09-01)
Ho, Cheng-Yuan
;
Chan, Yi-Cheng
;
Chen, Yaw-Chung
;
資訊工程學系
;
Department of Computer Science
In this article, we present a new slow-start variant, which improves the throughput of transmission control protocol (TCP) Vegas. We call this new mechanism Gallop-Vegas because it quickly ramps up to the available bandwidth and reduces the burstiness during the slow-start phase. TCP is known to send bursts of packets during its slow-start phase due to the fast window increase and the ACK-clock based transmission. This phenomenon causes TCP Vegas to change from slow-start phase to congestion-avoidance phase too early in the large bandwidth-delay product (BDP) links. Therefore, in Gallop-Vegas, we increase the congestion window size with a rate between exponential growth and linear growth during slow-start phase. Our analysis, simulation results, and measurements on the Internet show that Gallop-Vegas significantly improves the performance of a connection, especially during the slow-start phase. Furthermore, it is implementation feasible because only sending part needs to be modified.
Quick Vegas: Improving performance of TCP Vegas for high bandwidth-delay product networks
(2008-04-01)
Chan, Yi-Cheng
;
Lin, Chia-Liang
;
Ho, Cheng-Yuan
;
資訊工程學系
;
Department of Computer Science
An important issue in designing a TCP congestion control algorithm is that it should allow the protocol to quickly adjust the end-to-end communication rate to the bandwidth on the bottleneck link. However, the TCP congestion control may function poorly in high bandwidth-delay product networks because of its slow response with large congestion windows. In this paper, we propose an enhanced version of TCP Vegas called Quick Vegas, in which we present an efficient congestion window control algorithm for a TCP source. Our algorithm improves the slow-start and congestion avoidance techniques of original Vegas. Simulation results show that Quick Vegas significantly improves the performance of connections as well as remaining fair when the bandwidth-delay product increases.
TCP-Ho: A congestion control algorithm with design and performance evaluation
(2007-03-01)
Ho, Cheng-Yuan
;
Chan, Yi-Cheng
;
Chen, Yaw-Chung
;
資訊工程學系
;
Department of Computer Science
A critical design issue of Transmission Control Protocol (TCP) is its congestion control that allows the protocol to adjust the end-to-end communication rate based on the detection of packet loss. However, TCP congestion control may function poorly during its slow start and congestion avoidance phases. This is because TCP sends bursts of packets with the fast window increase and the ACK-clock based transmission in slow start, and respond slowly with large congestion windows especially in high bandwidth-delay product (BDP) networks during congestion avoidance. In this article, we propose an improved version of TCP, TCP-Ho, that uses an efficient congestion window control algorithm for a TCP source. According to the estimated available bandwidth and measured round-trip times (RTTs), the proposed algorithm adjusts the congestion window size with a rate between exponential growth and linear growth intelligently. Our extensive simulation results show that TCP-Ho significantly improves the performance of connections as well as remaining fair and stable when the BDP increases. Furthermore, it is feasible to implement because only sending part needs to be modified.