From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qv1-xf30.google.com (mail-qv1-xf30.google.com [IPv6:2607:f8b0:4864:20::f30]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 46D303B29D for ; Sun, 1 Dec 2019 13:06:22 -0500 (EST) Received: by mail-qv1-xf30.google.com with SMTP id q19so3680005qvy.9 for ; Sun, 01 Dec 2019 10:06:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:reply-to:subject:to:references:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=H/cW1J9S1lBIC+yJxjmaROn/BHuRH5kDJAJLgLj55vA=; b=iuCT/6A8/1wil2SBr883gOGxxDaV1MbZz7ZZk1zPkVexTCfLVwDaSPkNEZizgWUSqd FodUq8FZjQ22C4/VIIadYz/8q7Yd9uy37jtPhOxC891AHbijZ1alrJeFYPuM7R/MdVe+ aqgDNGPOpk/GO7lp0jAJkY9Mrha+nzarbeFSPN6iL472ng2J11/JzTpmyyaOl5DsizyZ K8N2Wk8Vq/+TCBdGXE9V+dSAeXHFGtiF2Xx1qp652W/8TiuDGOoCSRdyP/AH9ngNM/+B PYjN6VBOpcPHeBOzr+fOh4KVc9HU1QHwLauzLyNbbKpicTMYurhngMyRD0sjtuMPOImg deSg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:reply-to:subject:to:references:message-id :date:user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=H/cW1J9S1lBIC+yJxjmaROn/BHuRH5kDJAJLgLj55vA=; b=iNLDoKm6Pgr6ij7sQ0FgA0uR7H0mN0hOA3R/qAwHXluHKaWNlzRJO6CsP27XpMnnh+ HqYxIqgkrymu4BPj5O7hPp1gu1AIhHvdkGQcwxp/56DaPphWRBotqc5R1VWsgjtMlFvZ 0CX2k4L9adwGZjjCwabTkgoV6Wl/AWz/mjjRTq5G2VOpi+N7cgPY7LCB/wffocjyFPs+ z0uJj+k95MhJ1Yuu8M/9XF/A/HKYW/pPQ5HBw+XPBWwqvoIn2tfPBOIDGqE568pX8042 OaikKoseYlcvUsLV5cVFOT5Hd3Og/sZnne5LSXuvAaikbKPywFM9+Oqs8/nGDsHXWV4u gtWw== X-Gm-Message-State: APjAAAXuoHVsf+OpXxfdZyh022/vgQdz9IwnWBPq1rtN/alrTWEiBWT4 PUWeYGHi8QGmOQHZA87L8w0= X-Google-Smtp-Source: APXvYqwN4NKlMok4IjUzVLM5jnhkR4KDX6RbObHa08sD440Z6VZtczm+8aG3bl5zcz3Dh9qCg0/duw== X-Received: by 2002:a05:6214:1189:: with SMTP id t9mr28797198qvv.153.1575223581761; Sun, 01 Dec 2019 10:06:21 -0800 (PST) Received: from ?IPv6:2607:fea8:5620:1699::7? ([2607:fea8:5620:1699::7]) by smtp.gmail.com with ESMTPSA id t207sm6568577qke.98.2019.12.01.10.06.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 01 Dec 2019 10:06:21 -0800 (PST) From: David Collier-Brown X-Google-Original-From: David Collier-Brown Reply-To: davecb@spamcop.net To: bloat@lists.bufferbloat.net References: <63E9C0E4-C913-4B2F-8AFC-64E12489BC65@gmail.com> <297503679.4519449.1575069001960@mail.yahoo.com> <54C976BC-DEC7-4710-9CFF-0243559D9002@gmail.com> <156EA284-C01D-4FAA-89F4-DB448795F7FC@gmx.de> <385CF47C-17AD-4A62-9924-068E1485FFD5@gmail.com> <8C5FD2CE-D24F-4998-A636-8F85279C67BA@gmail.com> <02703449-D6CE-497D-BDBD-D79542D0EACF@gmx.de> Message-ID: Date: Sun, 1 Dec 2019 13:06:19 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <02703449-D6CE-497D-BDBD-D79542D0EACF@gmx.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Subject: Re: [Bloat] [Ecn-sane] sce materials from ietf X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Dec 2019 18:06:22 -0000 I wonder if an inexpensive and credible test of the acceptability of (URG(0) && urgent pointer > 0) by middle boxes might be possible using load-testing/reachability services like NeoLoad or Pingdom? On 2019-12-01 11:35 a.m., Sebastian Moeller wrote: > Hi Jonathan, > > >> On Nov 30, 2019, at 23:23, Jonathan Morton wrote: >> >>> On 1 Dec, 2019, at 12:17 am, Carsten Bormann wrote: >>> >>>> There are unfortunate problems with introducing new TCP options, in that some overzealous firewalls block traffic which uses them. This would be a deployment hazard for SCE, which merely using a spare header flag avoids. So instead we are still planning to use the spare bit - which happens to be one that AccECN also uses, but AccECN negotiates in such a way that SCE can safely use it even with an AccECN capable partner. >>> This got me curious: Do you have any evidence that firewalls are friendlier to new flags than to new options? >> This influenced the design of AccECN as well; in an early version it would have used only a TCP option and left the TCP flags alone. When it was found that firewalls would often interfere with this, the three-bit field in the TCP flags area was cooked up. > > Belt and suspenders, eh? But realistically, the idea of using an accumulating SCE counter to allow for a lossy reverse ACK path seems sort of okay (after all TCP relies on the same, so there would be a nice symmetry ). > I really wonder whether SCE could not, in addition to its current bit, borrow the URG pointer field in cases when it is not used, or not fully used (if the MSS is smaller than 64K there might be a few bits leftover, with an MTU < 2000 I would expect that ~5 bits might still be usable in that rate case). I might be completely of to lunch here, but boy a nice rarely used contiguous 16bit field in the TCP header, what kind of mischief one could arrange with that ;) Looking at the AccECN draft, I see that my idea is not terribly original... But, hey for SCE having an additional higher fidelity SCE counter might be a nice addition, assuming URG(0), urgent pointer > 0 will not bleached/rejected by uninitiated TCP stacks/middleboxes... Indeed, do we know if this was what the studies used, that Mirja Kuhlewind referred to? --dave -- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest davecb@spamcop.net | -- Mark Twain