From owner-freebsd-net@FreeBSD.ORG Mon Oct 5 12:18:32 2009 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 731C81065670 for ; Mon, 5 Oct 2009 12:18:32 +0000 (UTC) (envelope-from rihad@mail.ru) Received: from mx39.mail.ru (mx39.mail.ru [94.100.176.53]) by mx1.freebsd.org (Postfix) with ESMTP id 2BFDF8FC18 for ; Mon, 5 Oct 2009 12:18:31 +0000 (UTC) Received: from [217.25.27.27] (port=9312 helo=[217.25.27.27]) by mx39.mail.ru with asmtp id 1MumWM-0000Tt-00; Mon, 05 Oct 2009 16:18:30 +0400 Message-ID: <4AC9E415.9040801@mail.ru> Date: Mon, 05 Oct 2009 17:18:29 +0500 From: rihad User-Agent: Mozilla-Thunderbird 2.0.0.22 (X11/20090706) MIME-Version: 1.0 To: Eugene Grosbein References: <20091005061025.GB55845@onelab2.iet.unipi.it> <4AC9B400.9020400@mail.ru> <20091005090102.GA70430@svzserv.kemerovo.su> <4AC9BC5A.50902@mail.ru> <20091005095600.GA73335@svzserv.kemerovo.su> <20091005100446.GA60244@onelab2.iet.unipi.it> <20091005100532.GC73335@svzserv.kemerovo.su> <4AC9C88A.5050509@mail.ru> <20091005113037.GA77999@svzserv.kemerovo.su> <4AC9DD72.9060802@mail.ru> <20091005120057.GA79942@svzserv.kemerovo.su> In-Reply-To: <20091005120057.GA79942@svzserv.kemerovo.su> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam: Not detected X-Mras: Ok Cc: freebsd-net@freebsd.org Subject: Re: dummynet dropping too many packets X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Oct 2009 12:18:32 -0000 Eugene Grosbein wrote: > On Mon, Oct 05, 2009 at 04:50:10PM +0500, rihad wrote: > >>>> Where has TCP slow-start gone? My router box >>>> isn't some application proxy that starts downloading at full 100 mbit/s >>>> thus quickly filling client's 1 mbit/s link. It's just a router. >>> While there is no or little competition for bandwidth from the router >>> to clients, TCP would work just fine. I suspect your shaping policy >>> makes heavy competition between clients. In this case, TCP behaves >>> not-so-well without help of router's good shaping algorythms >>> and taildrop is not good one. >>> >> Nothing fancy (i.e. no competition). Only tons of per-user pipes >> simulating the given throughput. > > You've mentioned previously: "The pipes are fine, each normally having > 100-120 concurrent consumers (i.e. active users)." > This IS competition between TCP flows inside each pipe. > Well, each user gets instantiated with a new copy of the pipe. Each such user counts towards the limit imposed by hash_size*max_chain_len for that pipe only. It would have been competition had I used dst-ip dst-ip 0xffffff00 or similar and not dst-ip 0xffffffff, _then_ all 256 users (determined by the mask) would compete for the pipe's bandwidth. So the only competition is in the uplink at our main Cisco, I guess.