From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rcdn-iport-1.cisco.com (rcdn-iport-1.cisco.com [173.37.86.72]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id BCAEA3B2DF for ; Wed, 2 Mar 2016 13:09:08 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=3213; q=dns/txt; s=iport; t=1456942148; x=1458151748; h=from:to:cc:subject:date:message-id:references: in-reply-to:mime-version; bh=fp0Ufdxx9LtYg7SlcukB/GeZElJOHA9ya2pBQjTr1+0=; b=FMAn/VpR7rmLzGHUX1f7bleDiKmeQ/JZLMdI5tiq/UYkMXAq+7arxGSl Y6Drh9aEezVNBGHS+NZ8ZoMvwAQIs4g8MgNT+2Y4G9ylLnF4JV5VP9KEW 4pFNCWz2u/t6CNiMc+JvC+BjDGcpnezcZfn5yU5BZes4C9ZLYIJ5J96PY U=; X-Files: signature.asc : 833 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0DKAgD8K9dW/49dJa1egzpSbQa4A4ITD?= =?us-ascii?q?oFnHIVzAoFIOBQBAQEBAQEBZCeEQQEBAQMBI1YFCwIBCBgqAgIyJQIEDgUOiAs?= =?us-ascii?q?IDqwGjxYBAQEBAQEBAQEBAQEBAQEBAQEBAQENBASHfgiCRoEehhcrgQ8FlxIBg?= =?us-ascii?q?wiBZWyICY52jksBHgFDgjCBNGqHYn4BAQE?= X-IronPort-AV: E=Sophos;i="5.22,529,1449532800"; d="asc'?scan'208";a="82546916" Received: from rcdn-core-7.cisco.com ([173.37.93.143]) by rcdn-iport-1.cisco.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Mar 2016 18:09:06 +0000 Received: from XCH-ALN-014.cisco.com (xch-aln-014.cisco.com [173.36.7.24]) by rcdn-core-7.cisco.com (8.14.5/8.14.5) with ESMTP id u22I96c1003222 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Wed, 2 Mar 2016 18:09:06 GMT Received: from xch-rcd-013.cisco.com (173.37.102.23) by XCH-ALN-014.cisco.com (173.36.7.24) with Microsoft SMTP Server (TLS) id 15.0.1104.5; Wed, 2 Mar 2016 12:09:05 -0600 Received: from xch-rcd-013.cisco.com ([173.37.102.23]) by XCH-RCD-013.cisco.com ([173.37.102.23]) with mapi id 15.00.1104.009; Wed, 2 Mar 2016 12:09:05 -0600 From: "Fred Baker (fred)" To: =?utf-8?B?RGF2ZSBUw6RodA==?= CC: "aqm@ietf.org" , "bloat@lists.bufferbloat.net" Thread-Topic: [Bloat] review: Deployment of RITE mechanisms, in use-case trial testbeds report part 1 Thread-Index: AQHRdK6bchJ0Q/1vakiwND7wUkwWlA== Date: Wed, 2 Mar 2016 18:09:05 +0000 Message-ID: <650D8A08-A9FF-4EDF-9374-B4DBF3EB87CD@cisco.com> References: <56BB8F05.2030006@mti-systems.com> <56D1F349.6040601@taht.net> In-Reply-To: <56D1F349.6040601@taht.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: yes X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3112) x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.19.64.122] Content-Type: multipart/signed; boundary="Apple-Mail=_49579641-7DD5-4149-8B0B-938C8C6AFCA4"; protocol="application/pgp-signature"; micalg=pgp-sha1 MIME-Version: 1.0 Subject: Re: [Bloat] review: Deployment of RITE mechanisms, in use-case trial testbeds report part 1 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: Wed, 02 Mar 2016 18:09:09 -0000 --Apple-Mail=_49579641-7DD5-4149-8B0B-938C8C6AFCA4 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Feb 27, 2016, at 11:04 AM, Dave T=C3=A4ht wrote: >=20 > = https://reproducingnetworkresearch.wordpress.com/2014/06/03/cs244-14-confu= sed-timid-and-unstable-picking-a-video-streaming-rate-is-hard/ >=20 >> o the results are very poor with a particular popular AQM >=20 > Define "very poor". ? Presuming this is Adaptive Bitrate Video, as in Video-in-TCP, we (as in = Cisco engineers, not me personally; you have met them) have observed = this as well. Our belief is that this is at least in part a = self-inflicted wound; when the codec starts transmission on any four = second segment except the first, there is no slow-start phase because = the TCP session is still open (and in the case of some services, there = are several TCP sessions open and the application chooses the one with = the highest cwnd value). You can now think of the behavior of the line = as repeating a four phase sequence: nobody is talking, then one is = talking, then both are, and then the other is talking. When only one is = talking, whichever it is, its cwnd value is slowing increasing - = especially if cwnd*mss/rtt < bottleneck line rate, minimizing RTT. At = the start of the "both are talking" phase, the one already talking has = generally found a cwnd value that fills the line and its RTT is slowly = increasing. The one starting sends a burst of cwnd packets, creating an = instant queue and often causing one or both to drop a packet - reducing = their respective cwnd values. Depending on the TCP implementation in = question at the sender, if the induced drop isn't a single packet but is = two or three, that can make the affected session pause for as many RTO = timeouts (Reno), RTTs (New Reno), or at least retransmit the lost = packets in the subsequent RTT and then reduce cwnd by at least that = amount (cubic) and maybe half (SACK). --Apple-Mail=_49579641-7DD5-4149-8B0B-938C8C6AFCA4 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIVAwUBVtcsP0ayAOS/EQ8MAQLWLRAAl+WIc69YqN6zKo8EAHp5iAxRIudvDJ5j iYtBzHqBguE5xyjWlrsS6eRpQ/eBjZAHrDjDIwtwfw0XD/1BFq6Eusgl8dHbODBv Ao7j/6CvIoH7UcZ+v2bo1wprNv0oILTNsQFhUkB8oQEL2yi1qN+FTyH1u6hi/rdu oAQDgYLhwsygnxjlYcuK+DJ7ffVEnOo9xgsI40Ip9U5RPXPdt34LFxRPh/FVV72P VbCkQZ2RnUxbF5ua+9u9JDYRaoY9ZOKpCAMNsuFqRA3aF+9xgN1UUYZFwQ69Q6I1 6KrX5AOpL4Z8PTCwoTzEjlTqOgM+SA4tVgUSa5Rue5B7xw1qttEJlEU+Mlg2bH4a rTFR3X5bxL0VqYxhCeT8E9ivgj3l8OHgxpUXOsxUVvL8KtYr0qexSHa8vXK7GToX 3XLzhMV8k3GBUe5Yli8j7TAc1MRJxzhXWCPzJseqk+xwtwtC0h/eRu/D0bEk1w8S s9xC/RXENqHsDRr9YvjvgizmuegsYlB8FEDrEbye/v22LnA562yRvLOxzl075cgz sB6Z9+O3aQyX5qYfmjxfGvqn5E43KWywYaZ24ZVLId/FbtfojpU9waAx/sD5VX0/ Gvm+hVnKcTDraTNmvwwJwTJHOxKz3cTIsfgE/8mcMKW5nZqD0zUih9asyGxzx7oP pwhKDaCDq7c= =PBmV -----END PGP SIGNATURE----- --Apple-Mail=_49579641-7DD5-4149-8B0B-938C8C6AFCA4--