From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-02-ewr.dyndns.com (mxout-049-ewr.mailhop.org [216.146.33.49]) by lists.bufferbloat.net (Postfix) with ESMTP id 276CF2E0271 for ; Tue, 15 Mar 2011 10:59:51 -0700 (PDT) Received: from scan-02-ewr.mailhop.org (scan-02-ewr.local [10.0.141.224]) by mail-02-ewr.dyndns.com (Postfix) with ESMTP id 79F7373D47E for ; Tue, 15 Mar 2011 17:59:50 +0000 (UTC) X-Spam-Score: -1.0 (-) X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 72.29.103.198 Received: from zgp.org (allium.zgp.org [72.29.103.198]) by mail-02-ewr.dyndns.com (Postfix) with ESMTP id 2E57C73D43F for ; Tue, 15 Mar 2011 17:59:50 +0000 (UTC) Received: from goldfish.zgp.org (localhost [127.0.0.1]) by zgp.org (Postfix) with ESMTP id 3F22040046 for ; Tue, 15 Mar 2011 10:59:49 -0700 (PDT) Received: by goldfish.zgp.org (Postfix, from userid 500) id DEE8541267; Tue, 15 Mar 2011 10:59:42 -0700 (PDT) Date: Tue, 15 Mar 2011 10:59:42 -0700 From: Don Marti To: bloat@lists.bufferbloat.net Message-ID: <20110315175942.GA10064@goldfish> References: <4D7F4121.40307@freedesktop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [Bloat] Random idea in reaction to all the discussion of TCP flavours - timestamps? 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, 15 Mar 2011 17:59:52 -0000 begin Jonathan Morton quotation of Tue, Mar 15, 2011 at 06:47:17PM +0200: > On 15 Mar, 2011, at 4:40 pm, Jim Gettys wrote: > > > There is an interesting question about what "long term minimum" means here... > > VJ does expand on that in "RED in a different light". He means that the relevant measure of queue length is to take the minimum value over some interval of time, say 100ms or 1-2 RTTs, whichever is longer. The average queue length is irrelevant. The nRED algorithm in that paper proposes a method of doing that. It seems like a host ought to be able to track the dwell time of packets in its own buffer(s), and drop anything that it held onto too long. Timestamp every packet going into the buffer, and independently of any QoS work, check if a packet is "stale" on its way out, and if so, drop it instead of sending it. Is this in use anywhere? Haven't seen it in the literature I've read linked to from Jim's blog and this list. -- Don Marti http://zgp.org/~dmarti/ dmarti@zgp.org