Re: [tcpm] Further comments on draft-ietf-tcpm-accurate-ecn
Bob Briscoe <ietf@bobbriscoe.net> Sat, 21 July 2018 18:42 UTC
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To: "Scharf, Michael (Nokia - DE/Stuttgart)" <michael.scharf@nokia.com>, "draft-ietf-tcpm-accurate-ecn@ietf.org" <draft-ietf-tcpm-accurate-ecn@ietf.org>, "tcpm@ietf.org" <tcpm@ietf.org>
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From: Bob Briscoe <ietf@bobbriscoe.net>
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Date: Sat, 21 Jul 2018 12:23:27 +0100
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Subject: Re: [tcpm] Further comments on draft-ietf-tcpm-accurate-ecn
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Michael, There is no past tense in my suggested wording, and no implication that 5562 is obsolete. Nonetheless, I think you mean that I am saying RFC5562 is an older experiment than ECN++. Yes, I suggested we say it that way, 'cos that's a present fact. if anyone wants to read that as meaning that ECN++ is aiming to improve on 5562, that's fine 'cos that is also a fact. I didn't want the AccECN draft to say that ECN++ /does/ improve on 5562, because that's a judgement, not a fact. Bob PS. Nonetheless, you will see that the ECN++ draft says "Obsoletes: 5562 (if approved) " in the header block, and it provides very solid reasoning for why within the text. So the WG /is/ discussing that question, but you are right that it is not discussing that question in the context of the AccECN draft. On 18/07/18 14:12, Scharf, Michael (Nokia - DE/Stuttgart) wrote: > > The following wording might work for me: > > It is recommended that the AccECN protocol is implemented alongside > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > Therefore, this specification does not discuss implementing AccECN alongside > [RFC5562], which is an earlier experimental protocol. > > As far as I know, the experiment of RFC 5562 has not been officially > finished so far, i.e., use of past tense might not be appropriate. > > (Personally, I could imagine that TCPM decides to finish the > experiment of RFC 5562, but that question does not belong into this I-D.) > > Michael > > *From:*Bob Briscoe [mailto:ietf@bobbriscoe.net] > *Sent:* Wednesday, July 18, 2018 12:18 PM > *To:* Scharf, Michael (Nokia - DE/Stuttgart) > <michael.scharf@nokia.com>; draft-ietf-tcpm-accurate-ecn@ietf.org; > tcpm@ietf.org > *Subject:* Re: [tcpm] Further comments on draft-ietf-tcpm-accurate-ecn > > Michael, > > Sorry, I meant to add back in 'Therefore': > > It is recommended that the AccECN protocol is implemented alongside > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > Therefore, this specification does not discuss implementing AccECN alongside > [RFC5562], which was an earlier experimental protocol with narrower > scope than ECN++. > > > > Bob > > On 18/07/18 06:14, Bob Briscoe wrote: > > Michael, > > That regains the problem I said I was trying remove, of risking > implying "AccECN could also be combined with RFC5562, but this > isn't the place to talk about it?", by not explaining that ECN++ > subsumes the function of RFC5562. How about: > > It is recommended that the AccECN protocol is implemented alongside > > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > > This specification does not discuss implementing AccECN alongside > > [RFC5562], which was an earlier experimental protocol with narrower > > scope than ECN++. > > > > > Bob > > On 17/07/18 17:01, Scharf, Michael (Nokia - DE/Stuttgart) wrote: > > This wording would imply that ECN++ and RFC 5562 are indeed > “alternatives”. That is IMHO not fully correct, ECN++ seems to > have a broader scope. > > I think something along the lines of … > > It is recommended that the AccECN protocol is implemented alongside > > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > > This specification does not discuss implementing AccECN > > alongside the experimental protocol [RFC5562]. > > …does the job. > > Michael > > *From:*Bob Briscoe [mailto:ietf@bobbriscoe.net] > *Sent:* Tuesday, July 17, 2018 10:28 PM > *To:* Scharf, Michael (Nokia - DE/Stuttgart) > <michael.scharf@nokia.com> <mailto:michael.scharf@nokia.com>; > draft-ietf-tcpm-accurate-ecn@ietf.org > <mailto:draft-ietf-tcpm-accurate-ecn@ietf.org>; tcpm@ietf.org > <mailto:tcpm@ietf.org> > *Subject:* Re: [tcpm] Further comments on > draft-ietf-tcpm-accurate-ecn > > Michael, > > OK RECOMMENDED -> recommended. > That's good, otherwise I think ECN++ would have become a > normative reference. > > > > Alternatively, a more statement not related to the status > would be “a combination of AccECN with RFC 5562 is outside > the scope of this document”. > > Someone who had never even thought about combining AccECN with > RFC5562 might think we mean "AccECN could also be combined > with RFC5562, but this isn't the place to talk about it?" > > How about: > > It is recommended that the AccECN protocol is implemented alongside > > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > > Therefore, this specification does not discuss implementing AccECN > > alongside the earlier experimental alternative to ECN++ in [RFC5562]. > > > > > > Bob > > On 17/07/18 08:57, Scharf, Michael (Nokia - DE/Stuttgart) wrote: > > I would prefer the first, shorter wording. > > For instance, it would be possible that TCPM decides to > obsolete RFC 5562. I’d suggest to keep the status and > future use of RFC 5562 in combination with ECN++ outside > of this document. > > What might be in scope of the AccECN spec would be a > hypothetical use of AccECN in combination with RFC 5562. > But I would be fine with just omitting that. > Alternatively, a more statement not related to the status > would be “a combination of AccECN with RFC 5562 is outside > the scope of this document”. > > Actually, I am also not sure if this paragraph is a good > example for RECOMMENDED in a capital letters. To me, the > following would be sufficient: > > It is recommended that the AccECN protocol is implemented along with > > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > > Michael > > *From:*Bob Briscoe [mailto:ietf@bobbriscoe.net] > *Sent:* Tuesday, July 17, 2018 2:43 PM > *To:* Scharf, Michael (Nokia - DE/Stuttgart) > <michael.scharf@nokia.com> > <mailto:michael.scharf@nokia.com>; > draft-ietf-tcpm-accurate-ecn@ietf.org > <mailto:draft-ietf-tcpm-accurate-ecn@ietf.org>; > tcpm@ietf.org <mailto:tcpm@ietf.org> > *Subject:* Re: [tcpm] Further comments on > draft-ietf-tcpm-accurate-ecn > > Michael, > > I've written the proposed edits into a local copy of > draft-08, which we'll post after this IETF. > > Wile writing the last point, I thought it best to add an > extra sentence. > > It is RECOMMENDED that the AccECN protocol is implemented along with > > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > > [I-D.ietf-tcpm-generalized-ecn] is a proposed alternative to another > > experimental scheme [RFC5562] so there is no need to implement RFC > > 5562 along with AccECN. > > > > > > Bob > > On 17/07/18 01:05, Scharf, Michael (Nokia - DE/Stuttgart) > wrote: > > This would for for me. > > Thanks > > Michael > > *From:*Bob Briscoe [mailto:ietf@bobbriscoe.net] > *Sent:* Tuesday, July 17, 2018 1:34 AM > *To:* Scharf, Michael (Nokia - DE/Stuttgart) > <michael.scharf@nokia.com> > <mailto:michael.scharf@nokia.com>; > draft-ietf-tcpm-accurate-ecn@ietf.org > <mailto:draft-ietf-tcpm-accurate-ecn@ietf.org>; > tcpm@ietf.org <mailto:tcpm@ietf.org> > *Subject:* Re: [tcpm] Further comments on > draft-ietf-tcpm-accurate-ecn > > Michael, > > On 15/07/18 16:54, Scharf, Michael (Nokia - > DE/Stuttgart) wrote: > > Hi all, > > > > While reading draft-ietf-tcpm-accurate-ecn-07, I noticed the following: > > > > > > Section 1. Introduction > > > > It is likely (but not required) that the AccECN protocol will be > > implemented along with the following experimental additions to the > > TCP-ECN protocol: ECN-capable TCP control packets and retransmissions > > [I-D.ietf-tcpm-generalized-ecn], which includes the ECN-capable SYN/ > > ACK experiment [RFC5562]; and testing receiver non-compliance > > [I-D.moncaster-tcpm-rcv-cheat]. > > > > [ms] I have commented on this section before. And I still dislike the term "likely". To me, "likely" is speculation. A neutral phrasing would be "... it is possible..." or "... it is useful...". Having said this, I observe that draft-moncaster-tcpm-rcv-cheat-03 was last updated in 2014. How "likely" is it that the AccECN protocol will be implemented along with a mechanism documented in an ID that has been written more than 10 years ago and not been updated for about 4 years? Are implementers indeed so interested in draft-moncaster-tcpm-rcv-cheat that an implementation is "likely"? > > > I agree. For ECN++, I think something like your > suggestion of "useful", or even RECOMMENDED is what is > needed here. I think the testing receiver compliance > one could be removed from the intro. It's mentioned > under testing for unexpected interference and under > integrity checking, which are sufficient. > > Also, this makes me notice that the word "includes" is > wrong. ECN++ intends to obsolete RFC5562, but I don't > think we need to mention that here (cos it might > change before ECN++ gets published). > > CURRENT TEXT: > > It is likely (but not required) that the AccECN protocol will be > > implemented along with the following experimental additions to the > > TCP-ECN protocol: ECN-capable TCP control packets and retransmissions > > [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>], which includes the ECN-capable SYN/ > > ACK experiment [RFC5562 <https://tools.ietf.org/html/rfc5562>]; and testing receiver non-compliance > > [I-D.moncaster-tcpm-rcv-cheat > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.moncaster-tcpm-rcv-cheat>]. > > PROPOSED TEXT: > > It is RECOMMENDED that the AccECN protocol is implemented along with > > the experimental ECN++ protocol [I-D.ietf-tcpm-generalized-ecn > <https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07#ref-I-D.ietf-tcpm-generalized-ecn>]. > > > > > > > > > > > > > Section 2.1. Capability Negotiation > > > > The TCP server sends the AccECN > > Option on the SYN/ACK and the client sends it on the first ACK to > > test whether the network path forwards the option correctly. > > > > [ms] According to Section 3.2.6, options are RECOMMENDED. While Section 2 is not normative, the whole Section 2 does not really describe well the actual requirements regarding options. This paragraph in Section 2.1 is one example for that. It would make sense to be more explicit in Section 2 to which extent options have to be supported. > > OK, we need to review section 2, to ensure it is > consistent with changes that have been made in the > normative section 3 since it was written. > > In this particular case, we already promised to check > (offlist with an implementer) that there was no text > that contradicted the optionality of the option stated > at the end of Section 3.2.6. > > I have already started this with a list I prepared > (also offlist) of which middlebox checking sections an > implementer could ignore if they were only reading but > not sending the TCP options. > > > > > Bob > > > > > > > -- > > ________________________________________________________________ > > Bob Briscoehttp://bobbriscoe.net/ > > > > > > -- > > ________________________________________________________________ > > Bob Briscoehttp://bobbriscoe.net/ > > > > > -- > > ________________________________________________________________ > > Bob Briscoehttp://bobbriscoe.net/ > > > > -- > > ________________________________________________________________ > > Bob Briscoehttp://bobbriscoe.net/ > > > > -- > ________________________________________________________________ > Bob Briscoehttp://bobbriscoe.net/ -- ________________________________________________________________ Bob Briscoe http://bobbriscoe.net/
- [tcpm] Further comments on draft-ietf-tcpm-accura… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scheffenegger, Richard
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scheffenegger, Richard
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Scharf, Michael (Nokia - DE/Stuttgart)
- Re: [tcpm] Further comments on draft-ietf-tcpm-ac… Bob Briscoe