From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from nm9-vm5.access.bullet.mail.bf1.yahoo.com (nm9-vm5.access.bullet.mail.bf1.yahoo.com [216.109.114.196]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id C0C7F21F3E2 for ; Fri, 27 Feb 2015 17:57:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rogers.com; s=s2048; t=1425088661; bh=Q+NTfgXRdQBIvDOjVjrMoXq7wD4CmATY4yZZUdVdreo=; h=Date:From:Reply-To:To:CC:Subject:References:In-Reply-To:From:Subject; b=UaZccUHDDpW1YZnQf+yPTVF1CqQXGMwCcWKYM/gmzc78XJq0Q1f/U617B8J/enTSX7h7fARZDeyRXtUPD2jNpZl/11ZsxKqI6C5M4F4oMoQcsJHGKhM1sANYpIjwos1XzvvjEETEmhtPSHVlsikOLqIWyloadFNt0fRl+tNoocaXl0SkO9GZXs0EbVoXo2IAAYis+0gILBUs4ivuYg3f+zak0xl/CChDgxdVnpJoSLzp10PpkmQe8eH21biedkMbWPnwX9smHmEbSRN7k/MOW7bBnGdfAO5oiXfpul1Xfg1eHWWobiV5CjomAAoQfdLDWO8hsyK9RI7SdX2OxlPmig== Received: from [66.196.81.155] by nm9.access.bullet.mail.bf1.yahoo.com with NNFMP; 28 Feb 2015 01:57:41 -0000 Received: from [98.138.226.242] by tm1.access.bullet.mail.bf1.yahoo.com with NNFMP; 28 Feb 2015 01:57:41 -0000 Received: from [127.0.0.1] by smtp113.sbc.mail.ne1.yahoo.com with NNFMP; 28 Feb 2015 01:57:41 -0000 X-Yahoo-Newman-Id: 848036.75813.bm@smtp113.sbc.mail.ne1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: e6UWI3wVM1lkw5VBwmPrNvUzfMBg04zlAYr0NJp6BV5Sl.Q o4SQnMncwhBkP3nQ2xppZeVrhxrjnVhuxAghWPD1B5EuRKhsw62yu7vnghVI dEP2JfHu5ylRAA7H456J1rh60LPFPx2XTDD6DBGKSbfEiaoyG4YowG7lCBZf 7DgdhEaN2JBKx2btzeUVumB1UbJFpJr5TdRscZmcLupV_pcphxPhysBQ.3ug RGZ0EFWHLVAhzJgrWAXKacCNUPFWsz7zX8LIhjIF5d4W_GankQvgNE5Ye6_Y KTI6FtjUYtkzZh4sIEg4Wnxd6Cp9vfyopU220QOPBhMBBJHikCHo1Oajjky3 qP9iV6Mj43dpetdO7a.Y8KAMsRl3SDJnVlbVWdVEaGg_6K.9kPyY3Zlf0j7i bAHoxGrCwxr5qgRZa7nVtnBJ75T04OOi4xPy0v.Vod1ZFmBbcwhI4VW3m2OB h_HdH._9.C1HdhaA2K4tGz.BU4Gb6z3dG.gHM2waeECzwtRJMMu1Ils9Yy0u s4193I45A4KpiZiaiAin2TaJDyJt8qdHMqxAq X-Yahoo-SMTP: sltvjZWswBCRD.ElTuB1l9j6s9wRYPpuyTNWOE5oEg-- Message-ID: <54F12094.5040200@rogers.com> Date: Fri, 27 Feb 2015 20:57:40 -0500 From: David Collier-Brown User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Richard Scheffenegger References: In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] About Packet Drop in Codel X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list Reply-To: davecb@spamcop.net List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 28 Feb 2015 01:58:12 -0000 On 02/27/2015 03:26 AM, From: Stephen Hemminger "Richard Scheffenegger" wrote: >> Hi Members, >> i am doing M.tech and my research topic is AQM. >> i tried to run codel with ns-2.35. >> And i found packet loss is more in codel as compared to RED. > More packet loss is no necessarily a bad thing. > You need to measure throughput and latency together. TCP isn't a normal queuing system: when it gets close to it's capacity, it throttles the sender, so that the system isn't driven into the load range where latency goes up and (effective[1]) throughput plummets. Instead, it does congestion *avoidance*, rather like deadlock avoidance, and levels off total bandwidth to something very close but just below to the link's capacity. Dropping a packet forces the sender to reduce their offered load and then try to increase it slowly until they exceed the maximum and it drops another packet. This is cool: instead of the latency vs load curve looking like "_/", it looks like "_", at something close to 99% bandwidth. Lovely low latency, near-maximum bandwidth. --dave -- [1. Effective throughput is what humans care about: x Mb/S. If your data is delayed 30 seconds, theoretical throughput doesn't change, but frames from a movie are horribly delayed, and in effect, throughput is horrid. This too is something that TCP does well, and people like Van Jacobsen and Neil Gunther understand, but simplistic users of queuing theory don't] I'm an ex-York University nerd and author, so if I can help in your efforts, drop me a line. -- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest davecb@spamcop.net | -- Mark Twain