An Efficient Approach to Performance Improvement of Different TCP Enhancements Using ECN

Salahuddin Muhammad Salim ZABIR  Ahmed ASHIR  Norio SHIRATORI  

IEICE TRANSACTIONS on Information and Systems   Vol.E85-D   No.8   pp.1250-1257
Publication Date: 2002/08/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on New Technologies in the Internet and their Applications)
fairness,  ECN,  mark-tail,  mark-front,  FIM,  

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Providing a fair allocation of bandwidth among different connections over the Internet without affecting link efficiency has been a challenging issue in the area of network performance improvement. Congestion signaling is essential for the purpose. Conventional TCP uses packet loss as an implicit indication of congestion. Several enhancements to TCP have been proposed for faster congestion recovery and thus to improve the network performance. However, packet loss reduces TCP goodput and adds large delay. Also the variance in the share of bandwidth obtained by each connection may become unaccepatbly high. To the contrary, Explicit Congestion Notification (ECN) indicates a congestion explicitly before it actually occurs. Therefore, ECN facilitates a faster congestion detection and contributes to the network performance improvement. In this paper, we consider the performance implications of employing different ECN strategies along with several TCP enhancement schemes. We also introduce a new ECN packet marking strategy FIM and evaluate its relative performance and suitability for deployment along with different TCP enhancements. Simulation results show the superiority of FIM over other existing marking strategies with different TCP enhancement schemes by providing the best fairness without hampering link efficiency. We also observe FIM maintains a more consistent delay bound than other strategies and as such, is more suitable for application in practical purposes.