Re: [tcpm] Comments for draft-ietf-tcpm-rfc8312bis-02

Vidhi Goel <vidhi_goel@apple.com> Tue, 08 June 2021 07:27 UTC

Return-Path: <vidhi_goel@apple.com>
X-Original-To: tcpm@ietfa.amsl.com
Delivered-To: tcpm@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 538F83A25E2; Tue, 8 Jun 2021 00:27:37 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.795
X-Spam-Level:
X-Spam-Status: No, score=-2.795 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=apple.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id R-OFkRyODpsJ; Tue, 8 Jun 2021 00:27:32 -0700 (PDT)
Received: from ma1-aaemail-dr-lapp01.apple.com (ma1-aaemail-dr-lapp01.apple.com [17.171.2.60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 60A1F3A25E0; Tue, 8 Jun 2021 00:27:32 -0700 (PDT)
Received: from pps.filterd (ma1-aaemail-dr-lapp01.apple.com [127.0.0.1]) by ma1-aaemail-dr-lapp01.apple.com (8.16.0.42/8.16.0.42) with SMTP id 1587I9aB003658; Tue, 8 Jun 2021 00:27:27 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=apple.com; h=from : message-id : content-type : mime-version : subject : date : in-reply-to : cc : to : references; s=20180706; bh=siVWHybPSSdQt7xujqC2F++FTmLP18wixeWY4EtPmAk=; b=J4ESKa33AjP2msfB5GcZlLhSmA0qHk/WKzxVJbuwWkHwgkBfST5oMjZXGEK/Rs4+lNHX qgZy4p8hA8z5N7QAxG+8GPzWAYIk80ylBS0NUCbiK0nho4GBGCMNaeAxJDHkk8xcQ5kP tpVlSSTPnGsmSfmWM58XB38ZvbCzVfGZhrJAS/3Z39hB5UBCeV80W/qx9CKAxIJwJSTy Fy+QLNDiVXsvHR4g7p7nNyz27Utfgb7/4xS7ojMcq9R4FsPsQ9kMNAeVOmaPyc247I/E 1477ke0J8niSyms6rmAX2+wT0kuFxo83i7lRYT6Oppj6lvSn/tjf3dAh3y1xfJZCE4wQ Eg==
Received: from rn-mailsvcp-mta-lapp04.rno.apple.com (rn-mailsvcp-mta-lapp04.rno.apple.com [10.225.203.152]) by ma1-aaemail-dr-lapp01.apple.com with ESMTP id 3907x42b9u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Tue, 08 Jun 2021 00:27:27 -0700
Received: from rn-mailsvcp-mmp-lapp01.rno.apple.com (rn-mailsvcp-mmp-lapp01.rno.apple.com [17.179.253.14]) by rn-mailsvcp-mta-lapp04.rno.apple.com (Oracle Communications Messaging Server 8.1.0.9.20210415 64bit (built Apr 15 2021)) with ESMTPS id <0QUD00LZZGPQQ5D0@rn-mailsvcp-mta-lapp04.rno.apple.com>; Tue, 08 Jun 2021 00:27:26 -0700 (PDT)
Received: from process_milters-daemon.rn-mailsvcp-mmp-lapp01.rno.apple.com by rn-mailsvcp-mmp-lapp01.rno.apple.com (Oracle Communications Messaging Server 8.1.0.9.20210415 64bit (built Apr 15 2021)) id <0QUD00D00GN2LE00@rn-mailsvcp-mmp-lapp01.rno.apple.com>; Tue, 08 Jun 2021 00:27:26 -0700 (PDT)
X-Va-A:
X-Va-T-CD: 22b197be277b53ec1f96ba572e51d931
X-Va-E-CD: 2e6d0a645fe3cddf8de77c8cd0c1fb6b
X-Va-R-CD: 3d9c06b14119c365e7637b357762e6ee
X-Va-CD: 0
X-Va-ID: 1b1dcbed-304e-441f-8d68-b9afd48a2f8f
X-V-A:
X-V-T-CD: 22b197be277b53ec1f96ba572e51d931
X-V-E-CD: 2e6d0a645fe3cddf8de77c8cd0c1fb6b
X-V-R-CD: 3d9c06b14119c365e7637b357762e6ee
X-V-CD: 0
X-V-ID: 7c3d3fa7-9a2c-43f9-9250-03f40db646b9
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-06-08_05:2021-06-04, 2021-06-08 signatures=0
Received: from smtpclient.apple (unknown [17.11.41.60]) by rn-mailsvcp-mmp-lapp01.rno.apple.com (Oracle Communications Messaging Server 8.1.0.9.20210415 64bit (built Apr 15 2021)) with ESMTPSA id <0QUD00QMJGPQ9X00@rn-mailsvcp-mmp-lapp01.rno.apple.com>; Tue, 08 Jun 2021 00:27:26 -0700 (PDT)
From: Vidhi Goel <vidhi_goel@apple.com>
Message-id: <E687289E-D807-4CAF-81F8-3CDEAB6E224D@apple.com>
Content-type: multipart/alternative; boundary="Apple-Mail=_FA8C4B90-C4EC-429D-AD40-6C84CF3B98A0"
MIME-version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.11\))
Date: Tue, 08 Jun 2021 00:27:25 -0700
In-reply-to: <8DEC1E1C-B8DD-4199-AA49-F6AB7EC7C35E@eggert.org>
Cc: Lars Eggert <lars@eggert.org>, draft-ietf-tcpm-rfc8312bis@ietf.org
To: "tcpm@ietf.org Extensions" <tcpm@ietf.org>, Yoshifumi Nishida <nsd.ietf@gmail.com>
References: <CAAK044Q6Xy72-xsNdJ5yP0PDdo08N9zmAWickf13788E4u8cJw@mail.gmail.com> <CAAK044TxNs1B3VA1NzEgXyCRXSb8MHSNKkXeac2UFstQu7e8Mg@mail.gmail.com> <CAAK044QSo-0E_QHWDqrDE2VLEzOFEA4SxnHSX9DSKvSg-8y+pg@mail.gmail.com> <8DEC1E1C-B8DD-4199-AA49-F6AB7EC7C35E@eggert.org>
X-Mailer: Apple Mail (2.3654.100.0.2.11)
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-06-08_05:2021-06-04, 2021-06-08 signatures=0
Archived-At: <https://mailarchive.ietf.org/arch/msg/tcpm/8PkGjqkP7Qxl-D8jxwYQbmEpKFI>
Subject: Re: [tcpm] Comments for draft-ietf-tcpm-rfc8312bis-02
X-BeenThere: tcpm@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: TCP Maintenance and Minor Extensions Working Group <tcpm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tcpm>, <mailto:tcpm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tcpm/>
List-Post: <mailto:tcpm@ietf.org>
List-Help: <mailto:tcpm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 08 Jun 2021 07:27:38 -0000

Hello Yoshi and folks,

As we are addressing the below issues raised by Yoshi, for one of the issues (https://github.com/NTAP/rfc8312bis/issues/64 <https://github.com/NTAP/rfc8312bis/issues/64>), it would be great if you could take a look and provide opinion about whether using alpha_aimd as a variable and then assigning a constant value to it for Cubic in the draft is confusing or not.

And, of course, you are welcome to look at other issues and provide your input.

Thanks,
Vidhi

> On Jun 1, 2021, at 2:18 AM, Lars Eggert <lars@eggert.org> wrote:
> 
> Hi,
> 
> many thanks for the review!
> 
> On 2021-6-1, at 11:35, Yoshifumi Nishida <nsd.ietf@gmail.com> wrote:
>> 1: While this draft focuses on only TCP,  CUBIC can actually be applied to other transport protocols
>>    such as QUIC, SCTP. Do we want to mention it in the draft or is it out of scope?
> 
> I've opened https://github.com/NTAP/rfc8312bis/issues/61 for this.
> 
> Note that we did discuss CUBIC for QUIC in https://github.com/NTAP/rfc8312bis/issues/45.
> 
>> 2: Section 3.1 "After a window reduction in response to a congestion event is
>>     detected by duplicate ACKs or Explicit Congestion Notification-Echo
>>     (ECN-Echo, ECE) ACKs [
>> RFC3168], CUBIC remembers the congestion window..."
>> 
>>   I think the events detected by RACK (or PTO for QUIC) can also be included here.
> 
> I opened https://github.com/NTAP/rfc8312bis/issues/62
> 
>> 3: Section 4.1.1
>>    It seems that the text version of the draft uses b_cubic and a_aimd, while the pdf version of the
>>    draft uses different names. But, I prefer to use the same names in both versions to avoid confusion.
> 
> The PDF is actually corrupt, due to a Unicode bug in the datatracker PDF generation. See https://github.com/NTAP/rfc8312bis/issues/46.
> 
>> 4: Section 4.2  I personally prefer to refer the equations in the draft as 'Equation' rather than 'Figure'  if there's
>>    no strong reason for it.
> 
> With kramdown-xml2rfc2629, it's unfortunately not possible to change this. We would need to add an RFC Editor Note instructing them to manually make the change. Opened https://github.com/NTAP/rfc8312bis/issues/63
> 
>> 5: Section 4.3  It seems to me that there are two meanings for a_aimd in this section.
>>    One is the additive factor for CUBIC and the other is a generic parameter for AIMD() function.
>>    This looks a bit confusing to me.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/64
> 
>> 6: Section 4.3  The description for P is required for Figure 3.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/65
> 
>> 7: Section 4.3  I think The analysis in [FHP00] doesn't include delayed ACK factor. So, the AIMD TCP model here
>>   can be a bit aggressive compared to a TCP that doesn't enable ABC and uses delayed ACK.
>>  This is fine, but I think it might be good to clarify it.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/66
> 
>> 8: Section 4.3  I am not very sure why segments_acked is used rather than byted_acked here. What is the benefit of it?
>>    How do we calculate when the acks are split?
>>   Also, I think it should be clarified that cwnd is expressed in segments here in this case.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/67
> 
>> 9: Section 4.3  "Note that once _W_est_ reaches _W_max_, that is, _W_est_ >= _W_max_, ..."
>>   I might miss something, but I'm not sure why  a_aimd can be set to 1 to be compatible with AIMD TCP.
>>   Does this mean b_cubic is also updated? If not, why this can be compatible?
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/68
> 
>> 10: Section 4.5: " The convex profile ensure that the window increases very slowly at the beginning.."
>>   I am wondering how much this part is accurate. Because of Principal 2,  even though cwnd is increased
>>   through convex profile, I think it will be overridden by linear growth by AIMD.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/69
> 
>> 11: Section 4.7: "we update w_max as follows, before the window reduction as described in section 4.6"
>>   I am wondering if reducing w_max is the right approach here. Because if we reduce w_max, CUBIC
>>   can exit from convex region earlier than the case where fast convergence is not used.
>>   It seems to me that keeping w_max and reducing only cwnd (using smaller value than b_cubic)
>>   look more conservative.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/70
> 
>> 12: Section 5.2 and Section 5.3. Do these results are based on the algorithms and the parameter values
>>   described in the draft?  If there're differences, I think it should be described.
> 
> Opened https://github.com/NTAP/rfc8312bis/issues/71
> 
> Thanks,
> Lars
> 
> 
> _______________________________________________
> tcpm mailing list
> tcpm@ietf.org
> https://www.ietf.org/mailman/listinfo/tcpm