From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.inria.fr", Issuer "TERENA SSL CA" (not verified)) by huchra.bufferbloat.net (Postfix) with ESMTPS id DDB5B21F0BA for ; Tue, 12 Feb 2013 01:37:31 -0800 (PST) X-IronPort-AV: E=Sophos;i="4.84,648,1355094000"; d="scan'208,217";a="2449493" Received: from mp-41068.rocq.inria.fr ([128.93.41.68]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/AES128-SHA; 12 Feb 2013 10:37:30 +0100 From: James Roberts Content-Type: multipart/alternative; boundary=Apple-Mail-2-102560831 Date: Tue, 12 Feb 2013 10:37:29 +0100 Message-Id: To: bloat@lists.bufferbloat.net Mime-Version: 1.0 (Apple Message framework v1085) X-Mailer: Apple Mail (2.1085) Subject: [Bloat] FQ_Codel v. FQ_LQD X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Feb 2013 09:37:32 -0000 --Apple-Mail-2-102560831 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 I have not been following Bufferbloat but a colleague forwarded to me = the latest post from Dave T=E4ht about FQ_Codel. It is good to see the = virtues of fair queuing are being rediscovered.=20 I think the work by Suter and co-authors on FQ in high capacity routers = is particularly relevant: B. Suter, T. Lakshman, D. Stiliadis, A. Choudhury, Buffer Management = Schemes for Supporting TCP in Gigabit Routers with Per-Flow Queuing, IEEE = Journal in Selected Areas un Communications, August 1999. = (http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=3D&arnumber=3D772451) They may have been the first to introduce "head drop". Actually they = advocated dropping from the front of the flow queue with longest backlog = (FQ_LQD). I am not sure why a more sophisticated AQM, like RED, ARED or = Codel, is better than longest queue drop. Another advantage of FQ_Codel highlighted in the report by Toke = H=F8iland-J=F8rgensen (notified on the list) is to give priority to = packets of newly active flows. This idea was already proposed in our = papers: A. Kortebi, S. Oueslati and J. Roberts. Cross-protect: implicit service = differentiation and admission control, IEEE HPSR 2004, Phoenix, USA, = April 2004.=20 A. Kortebi, S. Oueslati, J. Roberts. Implicit service differentiation = using Deficit Round Robin, Proceedings of ITC 19, Beijing, August 2005.=20= I have long been advocating per flow fairness as the basis of effective = traffic control so I hope you won't mind me recalling this prior work. Jim Roberts --Apple-Mail-2-102560831 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1 I = have not been following Bufferbloat but a colleague forwarded to me the = latest post from Dave T=E4ht about FQ_Codel. It is good to see the = virtues of fair queuing are being rediscovered. 

I think the = work by Suter and co-authors on FQ in high capacity routers is = particularly relevant:

B. Suter, T. Lakshman, D. Stiliadis, A. = Choudhury, Buffer Management Schemes
for Supporting TCP in Gigabit = Routers with Per-Flow Queuing, IEEE Journal in
Selected Areas un = Communications, August 1999. (http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=3D&arnumber=3D7724= 51)

They may have been the first to introduce "head drop". = Actually they advocated dropping from the front of the flow queue with = longest backlog (FQ_LQD). I am not sure why a more sophisticated AQM, = like RED, ARED or Codel, is better than longest queue = drop.

Another advantage of FQ_Codel highlighted in the report by = Toke H=F8iland-J=F8rgensen (notified on the list) is to give priority to = packets of newly active flows. This idea was already proposed in our = papers:

A. Kortebi, S. Oueslati and J. Roberts. Cross-protect: = implicit service differentiation and admission control,  IEEE HPSR = 2004, Phoenix, USA, April 2004. 
A. Kortebi, S. Oueslati, J. = Roberts. Implicit service differentiation using Deficit Round Robin, =  Proceedings of ITC 19, Beijing, August 2005. 

I have = long been advocating per flow fairness as the basis of effective traffic = control so I hope you won't mind me recalling this prior = work.

Jim Roberts

= --Apple-Mail-2-102560831--