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Sun, 17 Dec 2017 19:23:40 +0000 Received: from AM0PR0702MB3730.eurprd07.prod.outlook.com ([fe80::d1fe:f3ea:349d:cb9a]) by AM0PR0702MB3730.eurprd07.prod.outlook.com ([fe80::d1fe:f3ea:349d:cb9a%13]) with mapi id 15.20.0345.009; Sun, 17 Dec 2017 19:23:40 +0000 From: Kevin Darbyshire-Bryant To: Sebastian Moeller CC: Mark Captur , "cake@lists.bufferbloat.net" Thread-Topic: [Cake] overhead for double nat VDSL2 connection Thread-Index: AQHTdy3qgUm3w0Tg+kuDqKFWoXagc6NHp6GAgABDGQA= Date: Sun, 17 Dec 2017 19:23:40 +0000 Message-ID: <0FF17103-0A62-4645-98AC-E1680C4711E8@darbyshire-bryant.me.uk> References: <73C84EA7-2ADD-4914-BBDE-92E8408C106F@gmx.de> In-Reply-To: <73C84EA7-2ADD-4914-BBDE-92E8408C106F@gmx.de> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: yes X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=kevin@darbyshire-bryant.me.uk; x-originating-ip: [2a02:c7f:1232:22b::dc83] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; 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DIR:OUT; SFP:1101; SCL:1; SRVR:AM0PR0702MB3731; H:AM0PR0702MB3730.eurprd07.prod.outlook.com; FPR:; SPF:None; PTR:InfoNoRecords; MX:1; A:1; LANG:en; received-spf: None (protection.outlook.com: darbyshire-bryant.me.uk does not designate permitted sender hosts) spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: multipart/signed; boundary="Apple-Mail=_07EFD208-9EA0-4DEE-8C90-7A1930A37AD1"; protocol="application/pgp-signature"; micalg=pgp-sha256 MIME-Version: 1.0 X-OriginatorOrg: darbyshire-bryant.me.uk X-MS-Exchange-CrossTenant-Network-Message-Id: 2b5484fb-47b8-4376-ca71-08d54583ae2d X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Dec 2017 19:23:40.6812 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 9151708b-c553-406f-8e56-694f435154a4 X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM0PR0702MB3731 Subject: Re: [Cake] overhead for double nat VDSL2 connection X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 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, 17 Dec 2017 19:23:43 -0000 --Apple-Mail=_07EFD208-9EA0-4DEE-8C90-7A1930A37AD1 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On 17 Dec 2017, at 15:23, Sebastian Moeller wrote: >=20 > Hi Mark, >=20 >> On Dec 17, 2017, at 11:45, Mark Captur wrote: >>=20 >> My setup is as follows >>=20 >> vdsl2 modem doing pppoe itself and nat to 10.x.x.x -> lede master = eth0.2 (wan static ip in modem's DMZ) eth0.1 (lan) doing nat to = 192.168.1.x >>=20 >> Here is my current SQM config >> config queue 'eth1' >> option debug_logging '0' >> option verbosity '5' >> option qdisc 'cake' >> option qdisc_advanced '1' >> option ingress_ecn 'ECN' >> option egress_ecn 'NOECN' >> option qdisc_really_really_advanced '1' >> option script 'layer_cake.qos' >> option interface 'eth0.2' >> option enabled '1' >> option eqdisc_opts 'nat rtt 50000 bridged-ptm dual-srchost = diffserv4' >> option upload '2400' >> option linklayer 'ethernet' >> option overhead '8' >> option squash_dscp '1' >> option squash_ingress '1' >> option iqdisc_opts 'nat rtt 50000 bridged-ptm dual-dsthost' >> option download '0' >>=20 >> config queue >> option debug_logging '0' >> option verbosity '5' >> option download '0' >> option qdisc 'cake' >> option script 'layer_cake.qos' >> option qdisc_advanced '1' >> option squash_dscp '0' >> option squash_ingress '0' >> option ingress_ecn 'ECN' >> option qdisc_really_really_advanced '1' >> option egress_ecn 'ECN' >> option interface 'eth0.1' >> option enabled '1' >> option eqdisc_opts 'nat rtt 50000 bridged-ptm dual-dsthost = diffserv4' >> option upload '30000' >> option linklayer 'ethernet' >> option overhead '8' >>=20 >> Is the overhead correct? should i use the bridged-ptm keyword (or = should i use pppoe-ptm). Beware of using option linklayer =E2=80=98ethernet=E2=80=99 without = option linklayer_advanced =E2=80=981=E2=80=99 & option = linklayer_adaptation_mechanism =E2=80=98default=E2=80=99. Or use = linklayer =E2=80=98none=E2=80=99. Failure to do so will make = sqm-scripts use STAB for the link accounting (in essence it lies to cake = about the size of packets being passed through it). Better to use = cake=E2=80=99s built-in compensation - fewer modules, less code. I was bitten by this myself very recently, lost 4 hours of my life & = many recompiles before I realised an innocent looking setting = (linklayer_advanced) was messing with the packet size (seen by looking = at max_len from tc) >=20 > The overhead certainly seems confusing. Personally, I dislike = the overhead related compound keywords like *-ptm and would recommend = the following: > 1) remove the bridged-ptm from the eqdisc/iqdisc fields > 2) add "mpu 64" to the eqdisc/iqdisc fields > 3) set overhad to 8+18+4 =3D 30 bytes (you will need to account for = everything added on the bottleneck, so your packets will be MTU 1492, to = leave room for the PPPoE header that the modem adds). MTU 1492 ain=E2=80=99t necessarily so - some vdsl modems in bridge mode = support RFC 4638 with baby jumbo frames, thus supporting the normal = ethernet MTU of 1500 (and obviating the need to TCP MSS clamping) - ie. = if you can do it, you should ;-). You still need to account for the 8 = byte PPPOE overhead of course. > 4) DO not set the ptm keyword at all, instead make sure to set the = shaper bandwidth to <=3D sync bandwidth * 64/65 =3D sync bandwidth * = 0.984615384615 (to account for ptm's 64/65 encoding _without_ incurring = needless operations per packet). >=20 > 4) tell us about your ISP and plan ;) >=20 Cheers, Kevin D-B GPG fingerprint: 012C ACB2 28C6 C53E 9775 9123 B3A2 389B 9DE2 334A --Apple-Mail=_07EFD208-9EA0-4DEE-8C90-7A1930A37AD1 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEASyssijGxT6XdZEjs6I4m53iM0oFAlo2xDwACgkQs6I4m53i M0rwTQ//fE0rKtU0SPubwgwqzIqbTwoe9moiHCCtAands11EAUUxBnYM0mxnv552 OR4A9ae79PDVqcJX/ZmGlzH3a5yDR7eS5KL11y+x72Ss3HsqM9Tpn8DyyV7xXAIX FsLN5D9S8FH0z2oMBNH7JTkF1TE2ZkWlM607/nFzyV6IiruqnNalTbVNfVFf0EoC juvBo0p1pxYVluuw2c13b/7yFvnNNgfcqrCScB7JWM6GNgBvSyWSRIkKveozL1m1 1nSD+5Eodi+L6DsCDTNnzSmwxdUJrYva6RCa8l2daR+QtWVCxMg3GfSffZsAXJpw JtX0M4CWuRWW9EN5U4QmN/e9vPukU8eZyQr5g69ALuMIXbWhL+jy/g1Nk64Qa7F1 DeUsee1/4D+tccbEtpzHJOLukXAtPfmYp9jz2LG8BADNckfoasWLiUQnCd0wVx5+ WaUPmlSou2nK+o72sxZ4+WWk2LYys9CUATPYqdfm7C42gGVGRNjs5NS8Xtp02ugx 7NJSNmSHqsIIukFGzvlThxIlOTJ4KvcDkBdGEZxuLQGYrTGnK89r7Fa0mlnApQk4 C2YMkAupTzyMO55LGPcNDAGIC+HvBaWu1Vz5+a0SgYWv0Jkhr9rf3dt33V0PenIl mzWqpVZz7fGalSAVTqVXljf2P3qpKfMw0PrekMsbIt0qD4/kTPI= =zYlc -----END PGP SIGNATURE----- --Apple-Mail=_07EFD208-9EA0-4DEE-8C90-7A1930A37AD1--