An Age Priority Packet Discarding Scheme for ATM Switches on Internet Backbone

Hong-Bin CHIOU  Zsehong TSAI  

IEICE TRANSACTIONS on Communications   Vol.E81-B   No.2   pp.380-391
Publication Date: 1998/02/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on ATM Switching Systems for future B-ISDN)
Category: Control and performance
ATM,  switching,  buffering,  TCP/IP,  

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Although the performance degradation for TCP/IP over plain ATM during congestion can be reduced if switch buffer management techniques such as Early Packet Discarding (EPD) and Partial Packet Discarding (PPD) schemes are employed. However, we show via simulation that fairness among connections remains a problem. For example, the fairness among packets of different length is a well known unsolved issue for EPD. To improve fairness of TCP and UDP over an Internet backbone, we propose a new technique called the Age Priority Packet Discarding (APPD) scheme to be used along with EPD and PPD. We employ two simulation scenarios to examine the performance of APPD; the MPEG-I video over UDP protocol and the FTP over TCP protocol. The simulation shows that with APPD combined with EPD and PPD, fairness can be well maintained against different packet length, order of connections, as well as different propagation delays. In addition, packet loss probability can be reduced with APPD in all scenarios, and the improvement is especially significant for video over UDP protocol. Finally we discuss the hardware implementation technique of the APPD scheme.