ISSN : 1796-2021
Volume : 1    Issue : 3    Date : June 2006

Promote the Use of Explicit Delay Control
Xiaoyuan Gu, Dirk Markwardt and Lars Wolf
Page(s): 41-52
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The Internet is undergoing changes of its traffic mix, with the IP-based interactive multimedia
applications gaining momentum. According to studies, UDP-based multimedia traffic has in recent
years risen to above 25% of the overall Internet traffic volume, as compared to only 5% a decade
ago. To these delay sensitive real-time interactive multimedia applications, out of delay boundary
packets are usually obsolete. However the current Internet Protocol lacks a way to control the
lifetime of the packets effectively. In this paper, we propose the Explicit Delay Control (EDC) as a
viable packet lifetime control mechanism designed for such purpose. It uses an embedded
Maximum Tolerable Delay (MTD) field in an IPv4 option. The value of MTD is determined by taking
the application specific delay bound, measured round-trip-time, and the estimations of the path
propagation delay and transmission delay into account. At each network node, the MTD is deducted
by the singlehop delay. Packets that expire their lifetime are discarded and non-congestion related
delay losses are signaled to the sender to reduce inaccuracy in delay estimations and to adapt to
path changes. We implemented EDC in the Linux kernel. Our evaluation has shown that EDC can
ensure the “legality” of the packets, reduce the waste of bandwidth and processing time in the
networks, and help to alleviate congestions.

Index Terms
packet lifetime control, multimedia, network entertainment, quality of service