sfq_codel in ns2 is derived more from SFQ than DRR, and there are several substantial differences, although sfq_codel can be almost, but not quite, configured to act the same as the dual DRR version that is in the actual, shipping, fq_codel. The version of DRR fq_codel uses is more similar to "DRR+" and "DRR++", but is uniquely it's own.
You have to use sfq_codel VERY carefully in the ns2 version, as the ability to correctly generate a five tuple hash is not there. Correctly generating a 5 tuple is almost, but not quite, in the ns3 version, last I looked, and that ns3 version is MUCH closer to the actual fq_codel version deployed in the field, but still not quite the same thing. I have kind of lost track as to the right ns2 and ns3 versions to start from, also. Tom? in terms of setting up realistic scenarios: A common (actually, nearly universal) change to fq_codel in the field at low bandwidths (below 50mbit) is to use a reduced quantum (300 bytes). I don't remember how to do that right in the ns2 version. It has, after all, been 3 years of no interest from the academic community. Also the codel target and interval need to be tuned slightly, at below 2.5mbits to account for a single full length packet at those speeds. I am delighted by the sudden upsurge in interest in the *fq_codel versions but I would certainly appreciate more efforts on making the underlying simulations actually match the deployment, before everyone goes off writing papers again. See sch_fq_codel.c in the linux distributions since 3.6, see also codel.h there, and compare against what you have for ns2 and ns3. I completely lack time or funding to make sims match the (much better reality) at this point. Worst case, I would encourage you to test the sims verses the deployed code with the same exact tests, so you can see what differences exist. On Sat, Feb 28, 2015 at 9:34 AM, divya singla <[email protected]> wrote: > can anybody tell me is there any difference between fq_Codel and Sfq_Codel? > > > > _______________________________________________ > Codel mailing list > [email protected] > https://lists.bufferbloat.net/listinfo/codel > -- Dave Täht Let's make wifi fast, less jittery and reliable again! https://plus.google.com/u/0/107942175615993706558/posts/TVX3o84jjmb _______________________________________________ Codel mailing list [email protected] https://lists.bufferbloat.net/listinfo/codel
