From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f43.google.com (mail-pb0-f43.google.com [209.85.160.43]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id A2BEA21F0D7 for ; Sun, 5 Aug 2012 10:14:49 -0700 (PDT) Received: by pbcwz7 with SMTP id wz7so9125230pbc.16 for ; Sun, 05 Aug 2012 10:14:49 -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 :message-id:references:to:x-mailer; bh=PkYiu343OlBcnCIrRdLrpshrrxRPmWgEUnujSXxc3yw=; b=ki+bM3FPDoIDO7IqTnTCqBY0EuikU707FE5yivxnGf3LwqbVHUEE4A7X+16LXUG7KR cfmTpLGqAUmRKguucbwCLyBGpfm9qMw1d/PieFecj3Mp595ze0+uheOGCNvW0lf234ze 8MCs6mbwVea9RynOTWU8tssiXBXY3rcesxxEjRMA8nT4YsFkJUb88pPKPEUU79uJNAti 6TYQl5zogotRNkw6PuoE4rP9z8KN0aKTtoF1osU3iTMcBan9FCEq1muUzmEjn9tMehdw wlcD6vxVnuw+tHSdd00PsBGhgGDcoaPFLN7RJAi1OpYkhyaxKg2rSlriwz2tQOiSIh43 r82w== Received: by 10.66.84.229 with SMTP id c5mr12632451paz.12.1344186889263; Sun, 05 Aug 2012 10:14:49 -0700 (PDT) Received: from [192.168.1.104] (74-95-2-169-SFBA.hfc.comcastbusiness.net. [74.95.2.169]) by mx.google.com with ESMTPS id ph1sm7159831pbb.45.2012.08.05.10.14.46 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 05 Aug 2012 10:14:48 -0700 (PDT) Content-Type: multipart/signed; boundary="Apple-Mail=_C69A7D9F-0E7E-45AA-978E-0C5DF7E0054B"; protocol="application/pkcs7-signature"; micalg=sha1 Mime-Version: 1.0 (Mac OS X Mail 6.0 \(1485\)) From: Andrew McGregor In-Reply-To: <501EA636.8040603@pollere.com> Date: Sun, 5 Aug 2012 10:14:43 -0700 Message-Id: <2BD764A0-9F01-4691-8004-CCB8C4D31C95@gmail.com> References: <1344048299-26267-1-git-send-email-dave.taht@bufferbloat.net> <1344062738.9299.1453.camel@edumazet-glaptop> <501D99C4.20902@pollere.com> <7EB59257-1A8E-4567-8AD3-5016594565CC@gmail.com> <1344144623.9299.1557.camel@edumazet-glaptop> <501EA636.8040603@pollere.com> To: Kathleen Nichols X-Mailer: Apple Mail (2.1485) Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] [RFC PATCH] codel: ecn mark at target X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Aug 2012 17:14:50 -0000 --Apple-Mail=_C69A7D9F-0E7E-45AA-978E-0C5DF7E0054B Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 I don't think that's a real either/or question. ECN itself does not = mean that those flows get to scam the network; that's what my points 2 = and 3 are for. I guess that argues for the marking to be earlier than = drop onset, but right now that's just a guess. Properly working ECN TCP = should mean that with the right choice of marking pattern the result = should be much the same as non-ECN TCP for fairness, but less bursty and = with fewer delay events for the application. ECN isn't all that useful for bulk transfer TCP, but for things like = videoconferencing RTP it's really quite important to maintaining a good = user experience. So is congestion control; these applications are better = served by being consistently a bit slower than they are by bursting up = and down, because frequent resolution or frame rate changes are really = annoying to watch. ECN also serves many thin flow TCP applications well = (SSH for example). I have to think a bit more about what the right thing is; maybe marking = once or twice each time codel enters the dropping state, and then = dropping as usual. Don't take that as a real proposal, though, as this = is a quick response and a solid proposal deserves a lot more thought. Andrew On 5/08/2012, at 9:58 AM, Kathleen Nichols wrote: >=20 > So you want to provide an incentive to deploy ECN. This also provides = an > incentive to > scam the network. I think a bigger question is what is gained by doing > this? Is it more > important to deploy something called ECN than to have a = well-functioning > network? >=20 > Kathie >=20 > On 8/5/12 9:53 AM, Andrew McGregor wrote: >> Well, there's a lot of people at the IETF who really want to do other = things with ECN, but it seems like the simple version is far too = aggressive. >>=20 >> So, I think the desirable properties are something like: >> 1) Allow ECN flows to achieve the same or slightly higher throughput = to maintain an incentive to deploy it. >> 2) Still drop ECN flows eventually to avoid too much queue buildup. >> 3) Account somehow for the fact that marking takes longer to control = the queue (but we don't know how much longer). >>=20 >> Maybe mark ECN instead of dropping, but if we end up trying to = mark/drop twice in one round, drop the later packets? >>=20 >> Oh, and ECN nonce deployment is negligible, to the extent that there = are proposals in the IETF to reuse the bits for other things, and there = is no pushback on that. >>=20 >> Andrew >>=20 >> On 4/08/2012, at 10:30 PM, Eric Dumazet = wrote: >>=20 >>> On Sat, 2012-08-04 at 20:06 -0700, Andrew McGregor wrote: >>>> Well, thanks Eric for trying it. >>>>=20 >>>> Hmm. How was I that wrong? Because I was supporting that idea. >>>>=20 >>>> Time to think. >>>=20 >>> No problem Andrew ;) >>>=20 >>> Its seems ECN is not well enough understood. >>>=20 >>> ECN marking a packet has the same effect for the sender : reducing = cwnd >>> exactly like a packet drop. Only difference is avoiding the >>> retransmit[s]. >>>=20 >>> It cannot be used only to send a 'small' warning, while other = competing >>> non ECN flows have no signal. >>>=20 >>> As far as packet schedulers are concerned, there should be no = difference >>> in ECN marking and dropping a packet. I believe linux packet = schedulers >>> are fine in this area. >>>=20 >>> Now, there are fundamental issues with ECN itself, out of Codel = scope, >>> thats for sure. >>>=20 >>> How widely has been RFC 3540 deployed, anybody knows ? >>>=20 >>>=20 >>>=20 >=20 --Apple-Mail=_C69A7D9F-0E7E-45AA-978E-0C5DF7E0054B Content-Disposition: attachment; filename=smime.p7s Content-Type: application/pkcs7-signature; name=smime.p7s Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFLjCCBSow ggQSoAMCAQICEQDMQ2ZKvgsUYA5oQg5SjWfVMA0GCSqGSIb3DQEBBQUAMIGTMQswCQYDVQQGEwJH QjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYDVQQK ExFDT01PRE8gQ0EgTGltaXRlZDE5MDcGA1UEAxMwQ09NT0RPIENsaWVudCBBdXRoZW50aWNhdGlv biBhbmQgU2VjdXJlIEVtYWlsIENBMB4XDTExMTAwMTAwMDAwMFoXDTEyMDkzMDIzNTk1OVowJTEj MCEGCSqGSIb3DQEJARYUYW5kcmV3bWNnckBnbWFpbC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IB DwAwggEKAoIBAQC+buTRxzSXTQmMyUqaokLJit3xU5WVudxHijhKbGRSTgJ867L/v8+rNhSoFwCV MdKIu/M7apWgGkkA+MT/LjDFj63jLT+4nTTLIojXZdoezbpp/rQ2ViSbi54AjhZBQ5X+yH2xcXmG KpDhZjeZC1bvKNvBtdOHCAcrx1Ys1BNj+AhwridEX/KD0cq5xSsJhjDggF6XSUOsaiqBHR6fiQMi 7gH8EuFBh83oklb/pdreg1fQ7gKJk/Me/atIbE1gtbIR88oaCtXoHfZxgkFwagwMtBHdkxN+wcZy 9xx78el9Lxrjx2nMq50hRlj/bqg/m4rSox7//DKfx7bfKNZAiSMDAgMBAAGjggHkMIIB4DAfBgNV HSMEGDAWgBR6E04AdFvGeGNkJ8Ev4qBbvHnFezAdBgNVHQ4EFgQUXOXqNkq6sNbrD8B41dPko8Gs JucwDgYDVR0PAQH/BAQDAgWgMAwGA1UdEwEB/wQCMAAwIAYDVR0lBBkwFwYIKwYBBQUHAwQGCysG AQQBsjEBAwUCMBEGCWCGSAGG+EIBAQQEAwIFIDBGBgNVHSAEPzA9MDsGDCsGAQQBsjEBAgEBATAr MCkGCCsGAQUFBwIBFh1odHRwczovL3NlY3VyZS5jb21vZG8ubmV0L0NQUzBXBgNVHR8EUDBOMEyg SqBIhkZodHRwOi8vY3JsLmNvbW9kb2NhLmNvbS9DT01PRE9DbGllbnRBdXRoZW50aWNhdGlvbmFu ZFNlY3VyZUVtYWlsQ0EuY3JsMIGIBggrBgEFBQcBAQR8MHowUgYIKwYBBQUHMAKGRmh0dHA6Ly9j cnQuY29tb2RvY2EuY29tL0NPTU9ET0NsaWVudEF1dGhlbnRpY2F0aW9uYW5kU2VjdXJlRW1haWxD QS5jcnQwJAYIKwYBBQUHMAGGGGh0dHA6Ly9vY3NwLmNvbW9kb2NhLmNvbTAfBgNVHREEGDAWgRRh bmRyZXdtY2dyQGdtYWlsLmNvbTANBgkqhkiG9w0BAQUFAAOCAQEAgmf81vnsAnbcmIAyyqvEKxAK jRHerfreN10DK1ISkUJ//U4uffQV8sAGDtyIErzVFsW6NYRmFCMSE20M1ffbFpWUmXCtm/YTlkf1 5STVjTMNshDzMDhpjx99Z2J5RBJPZpXjwmpQnfKwB7zft9TcUSIb9FvZm33EKdF/XlS12U4Q9fsj 2shZf88RituX2+fCWfHoTWiFEhFUkLRtWf1YpgHpEXr82nqROxs/aWNlqtLnwTTu2ULr/WpUaRDs kom8gFZkMgw5kRfLpSXRrCFSORsZzkH2ooRxaJY7wMwZaCUS1am9DuwVy7gehoc3ZsjsDkMObZeu kx7Cg7GxIkgo+zGCA64wggOqAgEBMIGpMIGTMQswCQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRl ciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYDVQQKExFDT01PRE8gQ0EgTGltaXRl ZDE5MDcGA1UEAxMwQ09NT0RPIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2VjdXJlIEVtYWls IENBAhEAzENmSr4LFGAOaEIOUo1n1TAJBgUrDgMCGgUAoIIB2TAYBgkqhkiG9w0BCQMxCwYJKoZI hvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0xMjA4MDUxNzE0NDRaMCMGCSqGSIb3DQEJBDEWBBSku0z8 ADZUGYcRIjQPOtdjPMosYzCBugYJKwYBBAGCNxAEMYGsMIGpMIGTMQswCQYDVQQGEwJHQjEbMBkG A1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYDVQQKExFDT01P RE8gQ0EgTGltaXRlZDE5MDcGA1UEAxMwQ09NT0RPIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQg U2VjdXJlIEVtYWlsIENBAhEAzENmSr4LFGAOaEIOUo1n1TCBvAYLKoZIhvcNAQkQAgsxgayggakw gZMxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1Nh bGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVkMTkwNwYDVQQDEzBDT01PRE8gQ2xpZW50 IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEQDMQ2ZKvgsUYA5oQg5SjWfVMA0G CSqGSIb3DQEBAQUABIIBAIFogLvR5ZNeOAoM/omIAZloB+LYaGNc9ZGyAQmhQoLdgam3h4yKLdyd vTqIWNfqW9DxxvjAZuj1t2dXVA6kJ4hj/aOr5dScKmyu7/0o8pSSe6C5Me/pFiiiOL3IznjFMBHd Y4ZwYolzhm9roy0gg5/msC/KXr+a73Jq5EkreXvimUFW8aFDU8BKfj2cQi/6pGaFMd/MVqccz8+l NA4ZU5UdN835V/dtyvShRnQahaQfLqQtGMFOXCNrJLXl90DZTp59a51fV0YAuPS50jBKjvM4DAfQ 28DWXTrjkT259QrMJqOqZ6msMHUXzq/UBCGpmjHZqLbB3KvHyQ8vZbZn1nkAAAAAAAA= --Apple-Mail=_C69A7D9F-0E7E-45AA-978E-0C5DF7E0054B--