Re: [core] Martin Duke's Discuss on draft-ietf-core-new-block-11: (with DISCUSS and COMMENT)

[Martin Duke <[e-mail]>]

Wonderful, that is satisfactory. I will lift my discuss when the changes
land.

On Tue, May 4, 2021 at 9:33 AM <[e-mail]> wrote:

> Re-,
>
>
>
> We are not seeking for performance enhancement when determining Q-Block
> support. This why I indicated in my first reply that no change to the base
> CC is needed for that. We updated the text as follows:
>
>
>
> OLD:
>
>    With CoAP over UDP, the way a request message is rejected for
>
>    critical options depends on the message type.  A Confirmable message
>
>    with an unrecognized critical option is rejected with a 4.02 (Bad
>
>    Option) response (Section 5.4.1 of [RFC7252]).  A Non-confirmable
>
>    message with an unrecognized critical option is either rejected with
>
>    a Reset message or just silently ignored (Sections 5.4.1 and 4.3 of
>
>    [RFC7252]).  To reliably get a rejection message, it is therefore
>
>    REQUIRED that clients use a Confirmable message for determining
>
>    support for Q-Block1 and Q-Block2 Options.
>
>
>
> NEW:
>
>    With CoAP over UDP, the way a request message is rejected for
>
>    critical options depends on the message type.  A Confirmable message
>
>    with an unrecognized critical option is rejected with a 4.02 (Bad
>
>    Option) response (Section 5.4.1 of [RFC7252]).  A Non-confirmable
>
>    message with an unrecognized critical option is either rejected with
>
>    a Reset message or just silently ignored (Sections 5.4.1 and 4.3 of
>
>    [RFC7252]).  To reliably get a rejection message, it is therefore
>
>    REQUIRED that clients use a Confirmable message for determining
>
>    support for Q-Block1 and Q-Block2 Options.  This CON message can be
>
>    sent under base CoAP congestion control setup specified in
>
>    Section 4.7 of [RFC7252] (that is, NSTART does not need to be
>
>    increased).
>
>
>
> Cheers,
>
> Med
>
>
>
> *De :* Martin Duke [mailto:[e-mail]]
> *Envoyé :* mardi 4 mai 2021 17:28
> *À :* BOUCADAIR Mohamed TGI/OLN <[e-mail]>
> *Cc :* The IESG <[e-mail]>; [e-mail];
> [e-mail]; [e-mail]; [e-mail]
> *Objet :* Re: Martin Duke's Discuss on draft-ietf-core-new-block-11:
> (with DISCUSS and COMMENT)
>
>
>
> OK, we've reached understanding on the
> NON_PROBING_WAIT/NON_PARTIAL_TIMEOUT issue. Thank you for the edit.
>
>
>
> I also now understand that essentially every connection will have a
> Q-block exchange using CON. As this is an integral part of the protocol, I
> don't believe it's sufficient for Sec 7.1 to declare congestion control
> parameters out of scope, unless there's a normative reference to some other
> draft that explains how to do it.
>
>
>
> Thanks
>
> Martin
>
>
>
> On Tue, May 4, 2021 at 2:01 AM <[e-mail]> wrote:
>
> Hi Martin,
>
>
>
> Please see inline.
>
>
>
> Cheers,
>
> Med
>
>
>
> *De :* Martin Duke [mailto:[e-mail]]
> *Envoyé :* lundi 3 mai 2021 20:57
> *À :* BOUCADAIR Mohamed TGI/OLN <[e-mail]>
> *Cc :* The IESG <[e-mail]>; [e-mail];
> [e-mail]; [e-mail]; [e-mail]
> *Objet :* Re: Martin Duke's Discuss on draft-ietf-core-new-block-11:
> (with DISCUSS and COMMENT)
>
>
>
>
>
>
>
> On Fri, Apr 30, 2021 at 4:48 AM <[e-mail]> wrote:
>
> >
> > I can't reconcile (4.1) with the last sentence in (7.2).
>
> [Med] Why? 4.1 can be done with default CoAP setting. The purpose of this
> CON request is to determine support of the functionality. We made this
> change:
>
> OLD:
>    Congestion control for CON requests and responses is specified in
>    Section 4.7 of [RFC7252].  In order to benefit from faster
>    transmission rates, NSTART will need to be increased from 1.
>    However, the other CON congestion control parameters will need to be
>    tuned to cover this change.  This tuning is not specified in this
>    document given that the applicability scope of the current
>    specification assumes that all requests and responses using Q-Block1
>    and Q-Block2 will be Non-confirmable (Section 3.2).
>
> NEW:
>    Congestion control for CON requests and responses is specified in
>    Section 4.7 of [RFC7252].  In order to benefit from faster
>    transmission rates, NSTART will need to be increased from 1.
>    However, the other CON congestion control parameters will need to be
>    tuned to cover this change.  This tuning is not specified in this
>    document given that the applicability scope of the current
>    specification assumes that all requests and responses using Q-Block1
>    and Q-Block2 will be Non-confirmable (Section 3.2) apart from the
>                                                       ^^^^^^^^^^^^^^
>    initial Q-Block functionality negotiation.
>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
>
> Does the functionality negotiation in (4.1) involve something other than
> sending Q-Block options?
>
> *[Med] No. All what is needed is to send the options in a CON message as
> per:  *
>
>
>
>    To indicate support for Q-Block2 responses, the CoAP client MUST
>
>    include the Q-Block2 Option in a GET or similar request (FETCH, for
>
>    example), the Q-Block2 Option in a PUT or similar request (POST, for
>
>    example), or the Q-Block1 Option in a PUT or similar request so that
>
>    the server knows that the client supports this Q-Block functionality
>
>    should it need to send back a body that spans multiple payloads.
>
>    Otherwise, the server would use the Block2 Option (if supported) to
>
>    send back a message body that is too large to fit into a single IP
>
>    packet [RFC7959].
>
>
>
> If so, then (4.1) ought to clarify that it's what you mean. If it's just a
> GET or whatever, then the text here is fine, but there needs to be more on
> congestion control for confirmable messages.
>
>
>
>
>  Moreover, if
> > my reading of (4.1) is correct, it's not sufficient to declare
> > congestion control guidance out of scope when it's a mandated part of
> > the protocol.
> >
>
> >
> > - (7.2) If NON_PROBING_WAIT and NON_PARTIAL_TIMEOUT both "have the
> > same value as computed for EXCHANGE_LIFETIME", why are they different
> > variables?
>
> [Med] Because they refer to distinct aspects that may be tweaked
> separately: the timeout induced by PROBING_RATE and the one to observe for
> expired partial bodies.
>
>  Or is that they SHOULD have the same value but might not?
> > A normative word would be helpful here.
>
> [Med] Not sure a change is needed here given the definition of the two
> parameters.
>
>
>
> But they can't be tweaked separately! The spec states that they are both
> computed as EXCHANGE_LIFETIME. It does not allow for them to be set
> separately.
>
> *[Med] Ah, I see what confuses you. We made this change:*
>
>
>
> *OLD:*
>
>    NON_PROBING_WAIT is used to limit the potential wait needed
>
>    calculated when using PROBING_RATE.  NON_PROBING_WAIT has the same
>
>    value as computed for EXCHANGE_LIFETIME (Section 4.8.2 of [RFC7252]).
>
>
>
>    NON_PARTIAL_TIMEOUT is used for expiring partially received bodies.
>
>    NON_PARTIAL_TIMEOUT has the same value as computed for
>
>    EXCHANGE_LIFETIME (Section 4.8.2 of [RFC7252]).
>
>
>
> *NEW:*
>
>    NON_PROBING_WAIT is used to limit the potential wait needed
>
>    calculated when using PROBING_RATE.  By default, NON_PROBING_WAIT has
>
>    the same value as EXCHANGE_LIFETIME (Section 4.8.2 of [RFC7252]).
>
>
>
>    NON_PARTIAL_TIMEOUT is used for expiring partially received bodies.
>
>    By default, NON_PARTIAL_TIMEOUT has the same value as
>
>    EXCHANGE_LIFETIME (Section 4.8.2 of [RFC7252]).
>
>
>
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