Date: Tue, 26 Aug 2014 14:43:49 +0000 From: "Eggert, Lars" <lars@netapp.com> To: George Neville-Neil <gnn@neville-neil.com> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: Patches for RFC6937 and draft-ietf-tcpm-newcwv-00 Message-ID: <814E0886-1B6B-4316-8BAB-684DAFDE1983@netapp.com> In-Reply-To: <B7145157-9A03-4053-BFCC-627633E20122@neville-neil.com> References: <259C9434-C6FE-42EA-823D-ECB024DBF3D7@netapp.com> <B7145157-9A03-4053-BFCC-627633E20122@neville-neil.com>
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Hi,
the newcwv patch is probably stale now with Tom Jones' recent patch =
based on a more up-to-date version of the Internet-Draft, but the PRR =
patch should still be useful?
Lars
On 2014-6-19, at 23:35, George Neville-Neil <gnn@neville-neil.com> =
wrote:
> On 4 Feb 2014, at 1:38, Eggert, Lars wrote:
>=20
>> Hi,
>>=20
>> below are two patches that implement RFC6937 ("Proportional Rate =
Reduction for TCP") and draft-ietf-tcpm-newcwv-00 ("Updating TCP to =
support Rate-Limited Traffic"). They were done by Aris =
Angelogiannopoulos for his MS thesis, which is at =
https://eggert.org/students/angelogiannopoulos-thesis.pdf.
>>=20
>> The patches should apply to -CURRENT as of Sep 17, 2013. (Sorry for =
the delay in sending them, we'd been trying to get some feedback from =
committers first, without luck.)
>>=20
>> Please note that newcwv is still a work in progress in the IETF, and =
the patch has some limitations with regards to the "pipeACK Sampling =
Period" mentioned in the Internet-Draft. Aris says this in his thesis =
about what exactly he implemented:
>>=20
>> "The second implementation choice, is in regards with the measurement =
of pipeACK. This variable is the most important introduced by the method =
and is used to compute the phase that the sender currently lies in. In =
order to compute pipeACK the approach suggested by the Internet Draft =
(ID) is followed [ncwv]. During initialization, pipeACK is set to the =
maximum possible value. A helper variable prevHighACK is introduced that =
is initialized to the initial sequence number (iss). prevHighACK holds =
the value of the highest acknowledged byte so far. pipeACK is measured =
once per RTT meaning that when an ACK covering prevHighACK is received, =
pipeACK becomes the difference between the current ACK and prevHighACK. =
This is called a pipeACK sample. A newer version of the draft suggests =
that multiple pipeACK samples can be used during the pipeACK sampling =
period."
>>=20
>> Lars
>>=20
>>=20
>> [prr.patch]
>>=20
>> [newcwv.patch]
>=20
> Apologies for not looking at this as yet. It is now closer to the top =
of my list.
>=20
> Best,
> George
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