UCAM-CL-TR-747: An estimator of forward and backward delay for multipath transport

[tech-r...@cl.cam.ac.uk]

Publication announcement:

An estimator of forward and backward delay for multipath transport

Fei Song, Hongke Zhang, Sidong Zhang, Fernando Ramos, Jon Crowcroft

Technical report UCAM-CL-TR-747, University of Cambridge,
Computer Laboratory, March 2009, 16 pages.

This document is now available at

http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-747.html

Abstract:

Multipath transport protocols require awareness of the capability of
different paths being used for transmission. It is well known that round
trip time (RTT) can be used to estimate retransmission timeout with
reasonable accuracy. However, using RTT to evaluate the delay of forward
or backward paths is not always suitable. In fact, these paths are
usually dissimilar, and therefore the packet delay can be significantly
different in each direction.

We propose a forward and backward delay estimator that aims to solve
this problem. Based on the results of the estimator, a new
retransmission heuristic mechanism for multipath transport is proposed.
With this same technique we also build two other heuristics: A
bottleneck bandwidth estimator and a shared congestion detector. These
help the sender to choose the high bandwidth path in retransmission and
ensure TCP-friendliness in multipath transport, respectively.

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University of Cambridge, Computer Laboratory,
Technical Reports (ISSN 1476-2986)
http://www.cl.cam.ac.uk/techreports/