From owner-freebsd-ipfw@FreeBSD.ORG Fri Jul 9 08:41:09 2004 Return-Path: Delivered-To: freebsd-ipfw@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E434816A4CE for ; Fri, 9 Jul 2004 08:41:09 +0000 (GMT) Received: from xorpc.icir.org (xorpc.icir.org [192.150.187.68]) by mx1.FreeBSD.org (Postfix) with ESMTP id D67FB43D55 for ; Fri, 9 Jul 2004 08:41:09 +0000 (GMT) (envelope-from rizzo@icir.org) Received: from xorpc.icir.org (localhost [127.0.0.1]) by xorpc.icir.org (8.12.9p1/8.12.8) with ESMTP id i698f78M036106; Fri, 9 Jul 2004 01:41:07 -0700 (PDT) (envelope-from rizzo@xorpc.icir.org) Received: (from rizzo@localhost) by xorpc.icir.org (8.12.9p1/8.12.3/Submit) id i698f7tk036105; Fri, 9 Jul 2004 01:41:07 -0700 (PDT) (envelope-from rizzo) Date: Fri, 9 Jul 2004 01:41:07 -0700 From: Luigi Rizzo To: Ian FREISLICH Message-ID: <20040709014107.A35991@xorpc.icir.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from if@hetzner.co.za on Fri, Jul 09, 2004 at 10:19:17AM +0200 cc: 'FreeBSD IPFW' cc: "Thomas S. Crum - 1WISP, Inc." Subject: Re: Dummynet Queue Weighting X-BeenThere: freebsd-ipfw@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: IPFW Technical Discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Jul 2004 08:41:10 -0000 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