Journal of South China University of Technology (Natural Science Edition) ›› 2007, Vol. 35 ›› Issue (1): 80-83,88.

• Computer Science & Technology • Previous Articles     Next Articles

Enhanced TCP Vegas Protocol for Asymmetric Networks

Liu Jing  Chen Fang-jiong  Wei Gang   

  1. School of Electronic and Information Engineering , South China Univ. of Tech. , Guangzhou 510640 , Guangdong , China
  • Received:2006-03-13 Online:2007-01-25 Published:2007-01-25
  • Contact: 刘靖(1973-) ，女，工程师，博士生，主要从事流量控制和IP QoS 方面的研究。 E-mail:liuj7@gdtel.com.cn
  • About author:刘靖(1973-) ，女，工程师，博士生，主要从事流量控制和IP QoS 方面的研究。
  • Supported by:

    国家自然科学基金资助项目( 60402014) ;广东省自然科学基金资助项目(31390 )

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Abstract:

It has been proved that the TCP Vegas protocol underutilizes the available bandwidth in asymmetric net-worksalthough it possesses better performance than the traditional TCP protocol. In order to solve this problem , an enhanced TCP Vegas algorithm is proposed. In this algorithm , the ecn_to_echo_bits in the acknowledge packets are firsL used to estimate the congestion probability in the backward path , proving that the change of Round -Trip-Time (RTT) is directly proportional to the change of congestion probability. Then , when backward congestion occurs ,the change of RTT is estimated by monitoring the change of congestion probability. Thus , the actual RTT before the congestion is obtained , which is used to implement the TCP Vegas protocol. The simulations based on NS-2 show that the proposed algorithm is more applicable than the existing Vegas algorithm when the congestion occurs both in forward and backward paths.

Key words: flow control, asymmetric network, TCP Vegas protocol