[e2e] packet-pair probe implementation

[Rik Wade]

On Thu, 01 May 2003, Atsuo J. wrote:

> Is the packet-pair probe (bandwidth estimation) technique (introduced by Keshav and revised by Paxson) really useful in the realistic network?Does anybody test it on the real testbed? Also, are there any real implementation/usage of this technique at all? Your suggestions will be very appreciated. Atsuo

I am not aware of any real world implementations of a packet-pair estimator
other than those mentioned. However, I did a great deal of work with 
packet-pair as part of my PhD thesis in the Real and NS simulators. I have
an implementation of packet-pair for both simulators if anyone would
like the source code.

At least in a simulation environment packet-pair was very effective, at least
until the congestion became so great that probe packets were regularly lost.
One concept which I believe has been enhanced in recent work is the concept
us using "packet trains" as opposed to isolated pairs. I recall reading
a paper (http://www.sics.se/~bengta/train.ps.gz) in 1999 on the subject.
This technique involves sending a stream of back-to-back packets, the 
interarrival properties of which can be measured and manipulated to suit
your requirements. Searching Google for "packet train bandwidth probe" 
brought up quite a few hits.

In my work, I combined a packet-pair startup phase with a pro-active 
congestion avoidance algorithm (a slightly simplified Vegas-like routine).
The congestion window was also replaced with a token bucket model (the
rate of which was governed by the initial probe phase and then adjusted
according to RTT variation) in order to better facilitate burstiness at the 
application layer. This proved highly effective in simulation, but I have 
not progressed to practical implementation. The papers and thesis from 
this work can be downloaded from http://www.rikwade.com. Source code is
available on request.
--
rik