From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id B86A021FB69; Thu, 30 Jul 2015 14:35:32 -0700 (PDT) Received: from hms-beagle-2.home.lan ([87.164.163.215]) by mail.gmx.com (mrgmx003) with ESMTPSA (Nemesis) id 0ML7NR-1ZLCbJ3LeL-000IIo; Thu, 30 Jul 2015 23:35:28 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Sebastian Moeller In-Reply-To: <356F5FEE-9FBD-4FF9-AC17-86A642D918A4@gmail.com> Date: Thu, 30 Jul 2015 23:35:26 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <5CC1DC90-DFAF-4A4D-8204-16CD4E20D6E3@gmx.de> References: <356F5FEE-9FBD-4FF9-AC17-86A642D918A4@gmail.com> To: Jonathan Morton X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:48NOiYLa2DhSdH/tUuDz3N83Hq4UBdV068S0262QG05O58n55Or M0YjAC3Nac00XRIPt5UgzCp2vfEEFNs/wet87sXP9SaOJyJ5sjA/jB21hYHEwY7VNXpusTW ySl4DXjLsvq3aibB1bHWOnJj4omNjLSRuwTIduBl/eECdvHsloFUe6SBqfmw5IrqUKU60Bf vujX2J0IsfjbziY6GEFJw== X-UI-Out-Filterresults: notjunk:1;V01:K0:giywe3tB1/8=:7ZW2yzbEVlrInkzwJgqEUs H1YIj9bl/Nd2MsXayTCdKiBLQPWVFR8RFAWZBMGCQLL0OtugN1qNxAl9k1W10gH0B189qsJWQ XDSe1Mqv0/PQDKuaT06ObUXg0x11DxfWupHEAdR9IWKO9TJ1rokQYluD6KvpQv9oiyDCjyHph BKgyBrD3rfsuDlEkcF86rxBIDQ5IbEySElkisoem8wFvoDQTWQpdMmduDsR7HD6tsbz2NmCCk CCOKXThToqDUtKO9jgPye02+0aaynUZVTEFgy0q4ldccoV7mRpfn2amwYvWyLpcsHxX6FrJl7 /P+zWESIGsbcVI5z7YKdD696wMO6o5CV3E6+A29wBUNuhlp3JZ39m1WU86paUllckv8Pdi2qU rHKs1+JARcpivGP17py7ae13/bxtOlNxUgm6dJ40Fmh16mGj52+/drz8vbpjlAPSoxnEEYe9/ hq+pgE50lfFey3ikHnh0AK8wR2KDxbx67VgeqopnSCe2l/8rN1OW9BFRCNh6X3bgL3ux9ac7O DhrIloyL/lF1U+EbtGhXLNj74sUKOPVeRASc7od6+/hztCPq1/YKF9c+8nuG1Q48EWqSuzbE4 8w6h+Ye2VgftBwZciZbddyj1x3it5Dn2SPiDsYmDifNF2Q9aymIcMI3pP7hX6l7ccFsqHa6hm 9HrWfb1BRVUYwPZcmoYeb9J9tJnzEASPL56HuPDUa18UqgcAXMKn3GgbP7jd1L7UwJJY= Cc: make-wifi-fast@lists.bufferbloat.net, "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Make-wifi-fast] [Cerowrt-devel] [tsvwg] Comments on draft-szigeti-tsvwg-ieee-802-11e X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Jul 2015 21:36:01 -0000 Hi Jonathan, nice information about the competing schemes (and I do not consider my = rant a proposed scheme ;) ) But looking at https://en.wikipedia.org/wiki/IEEE_802.11e-2005 I learn = that AC_VO gets 1.5ms guaranteed TXOP (roughly air-time), AC_VI gets 3ms = and BE and BK only get a single MSDU. Even assuming this means an = A-MSDU which as far as I can tell reaches up to 8K (in 802.11n, no idea = about ac). If I do the math I see that from roughly 42 Mbps on AC_VO = actually gets more airtime than BE and BK, AC_VI by the same logic = reaches parity with BK and BE from 21 Mbps on. So for a well set up wifi = net both VI and VO will get preferred media access and a larger = bandwidth share, I hope I misunderstood something, but basically this = means that the incentives to choose the correct AC shift with available = bandwidth. So from speeds > 21 Mbp any client or AP should use AC_VI = exclusively and above 42 AC_VO, or do I miss something here (can = clients/STAs actually enforce their marking or does the AP call the = shots)? Anyway, for me it seems that the whole IEEE 802.11e thing might = contain dragons=85 (but most likely I simple do not grasp the beauty of = 802.11e, for all I know it might actually be well-designed) Best Regards Sebastian On Jul 30, 2015, at 22:29 , Jonathan Morton = wrote: >> https://datatracker.ietf.org/doc/draft-szigeti-tsvwg-ieee-802-11e/ >=20 >> On the topic of the actual mappings.... >=20 > Here=92s a handy comparison table to show how the draft, CJ=92s = suggestions, and cake=92s current implementation map DSCPs to traffic = classes: >=20 > DSCP | SZ | CJ | Cake > --------------------- > CS7 | XX | VO | VO > CS6 | ?? | VO | VO > EF | VO | VO | VO > VA | VO | VO | VO > CS5 | VI | VO | VO > AF4x | VI | VI | VI > CS4 | VI | VI | VO > AF3x | VI | BE | VI > CS3 | VI | BE | VI > AF2x | BE | BE | VI > CS2 | BE | BE | VI > AF1x | BK | BE | BE > DF | BE | BE | BE > CS1 | BK | BK | BK > TOS4 | BE | BE | VI > TOS2 | BE | BE | BE > TOS1 | BE | BE | VI >=20 > Interesting to note that cake puts a lot more traffic in =93high=94 = classes than either of these suggestions. I also note that cake does = invert CS4 vs AF4x in a way that CJ doesn=92t like - but perhaps this is = mitigated by the fact that cake thresholds VI at three times the = bandwidth as VO, which I think is appropriate since video consumes more = bandwidth than voice (or games) traffic. >=20 > None of these suggestions make any practical distinction between the = =93drop probability=94 divisions within the AFxx classes - even though = in some cases they are mapped to distinct UP values, these always fall = into the same major class. I suppose that distinction would be better = left to an AQM algorithm that was aware of them, which cake is not since = I can=92t immediately see a way to make Codel respond reasonably to it. >=20 > The draft doesn=92t address the =93legacy=94 codepoints associated = with the old TOS bits, but cake does, so I extended the table = accordingly. >=20 > I couldn=92t quite decipher Sebastian=92s suggestions into table form, = so I omitted those. >=20 > The major =93dangerous=94 feature I see in the draft is the treatment = of CS6 and CS7 traffic - long on =93drop or remark=94 and short on =93if = you must, just stick it in VO". CS6 in particular is used by common NTP = implementations, and for good reason. As far as I=92m concerned, = equipment should *not* remark or drop traffic by default based solely on = its DSCP. Indeed, equipment should probably assume they are not acting = as the edge of a network domain unless specifically configured = otherwise. >=20 > - Jonathan Morton >=20 > _______________________________________________ > Make-wifi-fast mailing list > Make-wifi-fast@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/make-wifi-fast