From owner-freebsd-net@FreeBSD.ORG Mon Dec 10 21:22:16 2007 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 D170816A420 for ; Mon, 10 Dec 2007 21:22:16 +0000 (UTC) (envelope-from Stephen.Clark@seclark.us) Received: from smtpout06.prod.mesa1.secureserver.net (smtpout06-04.prod.mesa1.secureserver.net [64.202.165.227]) by mx1.freebsd.org (Postfix) with SMTP id AA12413C458 for ; Mon, 10 Dec 2007 21:22:16 +0000 (UTC) (envelope-from Stephen.Clark@seclark.us) Received: (qmail 6395 invoked from network); 10 Dec 2007 20:48:40 -0000 Received: from unknown (24.144.77.185) by smtpout06-04.prod.mesa1.secureserver.net (64.202.165.227) with ESMTP; 10 Dec 2007 20:48:40 -0000 Message-ID: <475DA624.4010104@seclark.us> Date: Mon, 10 Dec 2007 15:48:36 -0500 From: Stephen Clark User-Agent: Mozilla Thunderbird 1.0.8-1.1.fc4 (X11/20060501) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Luigi Rizzo References: <475D6FD7.2000500@mail.ru> <20071210120353.B40679@xorpc.icir.org> In-Reply-To: <20071210120353.B40679@xorpc.icir.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: rihad , freebsd-net@freebsd.org Subject: Re: Pipe queues X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Stephen.Clark@seclark.us List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Dec 2007 21:22:16 -0000 Luigi Rizzo wrote: >On Mon, Dec 10, 2007 at 11:22:33AM -0800, Chuck Swiger wrote: > > >>On Dec 10, 2007, at 8:56 AM, rihad wrote: >> >> >>>Hi, >>> >>>I'm having a hard time to understand what pipe queues are with >>>respect to bandwidth limitation. ipfw(8) and dummynet(4) manuals >>>didn't help me much. >>> >>> >>Pipes and queues are two different things; a pipe simulates a network >>link, and a queue is used to hold packets which are backlogged because >>they are arriving faster than the outbound link (ie, a pipe) can >>transmit them. >> >> >> >>>How does dummynet's traffic shaping function? >>> >>> >>It uses a variant of weighted fair queuing. >> >> > >actually the shaping uses a leaky bucket algorithm. >The weighted fair queuing is the queue management scheme used >when you have multiple queues attached to the same pipe > >cheers >luigi >_______________________________________________ >freebsd-net@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-net >To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > > > Pipes are used to limit bandwidth. Queues are used to assign priority to different classes of traffic. As an example suppose you wanted to limit bandwidth for a specific ip to 2mbs. You set up a pipe to do this and use ipfw to put traffic from this ip into the 2 mbs pipe. If you then wanted to prioritize ftp traffic at higher than priority than all other traffic for this same user you would create 2 queues to feed the 2mbs pipe. You would send the ftp traffic into the higher priority queue and all other traffic for this user into the other queue. hth, Steve -- "They that give up essential liberty to obtain temporary safety, deserve neither liberty nor safety." (Ben Franklin) "The course of history shows that as a government grows, liberty decreases." (Thomas Jefferson)