2011/5/6 Björn Scheuermann scheuermann@informatik.uni-wuerzburg.de: [...]
We implemented Tor's scheduling mechanisms, the N23 extension, and our fairness mechanism in an event-based network simulator (ns-3). Independent from the question of inter-circuit fairness, we were able to confirm the key findings in the DefenestraTor tech report with respect to N23 based on this independent implementation. Moreover, we found that N23 does not solve the fundamental fairness problems - but N23 in combination with our fairness mechanism does an excellent job in this regard.
We explain all this in much more detail in a paper:
F. Tschorsch, B. Scheuermann: Tor is Unfair - and What to Do About It http://robotik.informatik.uni-wuerzburg.de/tr481.pdf
We're hoping for feedback and vivid discussions - we would be really interested in bringing these mechanisms into Tor.
Hi! Let me kick the discussion off by asking how your work relates (if at all!) to:
1) This other work on using N23 with Tor ("DefenstraTor: Throwing out Windows in Tor" by AlSabah, Bauer, Goldberg, Grunwald, McCoy, Savage, and Voelker): http://www.cacr.math.uwaterloo.ca/techreports/2011/cacr2011-06.pdf (IMO it's a promising sign that two groups seem to be independently converging on the same basic algorithm family.)
2) The priority-queue-based circuit scheduling code originally merged in Tor 0.2.2.7-alpha (starting with commit d3be00e0f).
3) Your other scheduling/bandwidth allocation work (ticket 2536)
I'd also be interested in hearing what the DefenestraTor authors think about above-linked paper and the topic in general.
yrs,