Date: Fri, 9 Jul 2004 01:41:07 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Ian FREISLICH <if@hetzner.co.za> Cc: "Thomas S. Crum - 1WISP, Inc." <tscrum@1wisp.com> Subject: Re: Dummynet Queue Weighting Message-ID: <20040709014107.A35991@xorpc.icir.org> In-Reply-To: <E1BiqbF-000DWn-00@hetzner.co.za>; from if@hetzner.co.za on Fri, Jul 09, 2004 at 10:19:17AM %2B0200 References: <louie@TransSys.COM> <E1BiqbF-000DWn-00@hetzner.co.za>
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On Fri, Jul 09, 2004 at 10:19:17AM +0200, Ian FREISLICH wrote: ... > > > But, what if A&B(1) had no traffic? It is my understanding that > > > queue 2 and 3 would still only get 5/16 and 1/16 of the pipe > > > regardless. In this example, 3/8 or 375Kb/s total. Or would 2 and > > > 3 share the whole pipe if queue 1 is inactive, which would make my > > > questions moot? > > > > The answer to your question is that idle queue do not consume capacity > > on the pipe they are associated with. I have queue with weights 100 > > (for VoIP), 20 (for interactive SSH, NTP) and 1 (everything else) and > > the "everything else" traffic can use the full capacity of the pipe > > with the other queues are idle. > > This raises another question: how do the idle queues get shared? the only thing that is shared is the total pipe's capacity, and it is shared by non-idle queues in proportion to their weights. That's as simple as that. No special cases. There is a copious literature on Proportional Share algorithms, if you google for WF2Q+ (which is the algorithm implemented in dummynet) you should come up with a lot of papers to answer your doubts. We are finishing up a tutorial paper on the topic for which i will post a URL in a week or two when it is ready. cheers luigi
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