Fred Baker <[email protected]> writes: > On Mar 17, 2011, at 5:05 AM, Fred Baker wrote: > >> I'm very much in favor of ECN, which in all of the tests I have done has >> proven very effective at limiting queues to the knee. I'm also in favor of >> delay-based TCPs like CalTech FAST and the Hamilton and CAIA models; FAST >> tunes to having a small amount of data continuously in queue at the >> bottleneck, and Hamilton/CAIA tunes to a small bottleneck. The problem tends >> to be that the "TCP Mafia" - poorly named, but a smallish set of people who >> actually control widely-used TCP implementations - tend to very much believe >> in the loss-based model, in part because of poor performance from past >> delay-based implementations like Vegas and in part due to IPR concerns. >> Also, commercial interests like Google are pushing very hard for fast >> delivery of content, which is what is behind Linux' recent change to set the >> initial window segments. > > I didn't say, and should have said: I'm also in favor of AQM in any form; I > prefer marking to dropping, but both are signals to the end system. The issue > is that we need the right mark/drop rate, and the algorithms are neither > trivial nor (if the fact that after 20+ years Van and Kathy haven't yet > published a red-lite paper they're happy with is any indication) well > documented in the general case.
A mea culpa from a former ASIC designer, which discusses the relationship between propagation delay, burstiness, and the real need for something like RED, and why ASIC designers didn't make it more of a priority. "Our biggest mistake was in making queue management optional, and making it scary." Really well explained, with good diagrams, too. http://codingrelic.geekhold.com/2011/03/random-early-mea-culpa.html -- Dave Taht http://nex-6.taht.net _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
