From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-x236.google.com (mail-lb0-x236.google.com [IPv6:2a00:1450:4010:c04::236]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id F192421F306 for ; Sun, 12 Apr 2015 16:14:52 -0700 (PDT) Received: by lbbuc2 with SMTP id uc2so46590101lbb.2 for ; Sun, 12 Apr 2015 16:14:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=content-type:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=vtyOgdyiBqmniUTWPMuy+1DR7RuwOx5Ol91iGAAWOHw=; b=qaupNgqy+FfNYTYN2mqtwSGDMUcHG5VAuNpdwY6IJDIqbMq4+mQ9YlC4+D0P/rtM8E MVXjE6Bp+6dx/QiQLBVudTXJQ9hzOEIV9zoGiR8fNUJY77TrR3gXZJlCjX4guFR37iez 05gxQN6OGvkrr42rn1WOhIMKQuOTIRPeX+9jq/bh+H8HSoqL3gbPDMInjtbHfyiWMl+s emwiV0xKTbjHFgsrrnUzbybob9GLDXDBy+1rHqn8rAQM9dIYo8veOZnOmnzhFAjvTAh4 O6eP2AUS+hJ2MqNaUX/edKd3YXhTssc6rhw+SjRJxWBKTijGW14QjZiGW7rQBN0qW8Eq FzeA== X-Received: by 10.152.1.70 with SMTP id 6mr10707977lak.83.1428880490586; Sun, 12 Apr 2015 16:14:50 -0700 (PDT) Received: from bass.home.chromatix.fi (87-93-27-145.bb.dnainternet.fi. [87.93.27.145]) by mx.google.com with ESMTPSA id lc8sm1276462lbc.33.2015.04.12.16.14.44 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 12 Apr 2015 16:14:49 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) From: Jonathan Morton In-Reply-To: Date: Mon, 13 Apr 2015 02:14:39 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Dave Taht X-Mailer: Apple Mail (2.2098) Cc: cake@lists.bufferbloat.net Subject: Re: [Cake] cake exploration X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Apr 2015 23:15:21 -0000 > On 11 Apr, 2015, at 21:47, Dave Taht wrote: >=20 > 14) strict priority queues. Some CBR techniques, notably IPTV, want 0 > packet loss, but run at a rate determined by the provider to be below > what the subscriber will use. Sharing that "fairly" will lead to loss > of packets to those applications. >=20 > I do not like strict priority queues. I would prefer, for example, > that the CBR application be marked with ECN, and ignored, vs the the > high probability someone will abuse a strict priority queue. The new priority mechanism in cake3 actually still supports a hard = rate-limit function, albeit with a small amount of slop in it. You = would simply need to force the =E2=80=9Cbandwidth share=E2=80=9D quantum = value to zero, which would mean that the class involved only gets quanta = when it=E2=80=99s running within its limit. A sufficiently large =E2=80=9Cpriority share=E2=80=9D quantum value = would also behave an awful lot like strict priority. This is aided by = the fact that cake3 still charges the bandwidth of high priority classes = to all lower priority classes - but note that if the normal = strictly-decreasing structure of the classes is violated, it becomes = possible to force some of the high-priority classes to operate = permanently in bandwidth-sharing mode, robbing them of most of their = original benefit. I feel fairly strongly that this type of traffic should be handled in = one of two ways: - Mark it with an appropriate DSCP, such as CS3 or VA, and accept = contention if it occurs. - Permanently mark off the CBR bandwidth as unavailable to normal = traffic, and configure cake to use the remainder; use a separate = mechanism to have the CBR traffic bypass cake. This would be = particularly appropriate for a shared broadcast stream. As a variation on the second option, it may be that the CBR stream is = only present intermittently. In that case, cake can be reconfigured on = the fly by an external mechanism, to use either the full or reduced = bandwidth; the bypass mechanism should remain in place meanwhile. - Jonathan Morton