Re: [Ice] Tsvart last call review of draft-ietf-ice-pac-03

[Justin Uberti <[e-mail]>]

Added the bolded text below. Full details at
https://github.com/ice-wg/draft-ice-pac/pull/20.


*The RECOMMENDED duration for the timer is equal to the agent'sconnectivity
check transaction timeout, including all retransmissions. *

*When using default values for RTO and Rc, this amounts to 39.5 seconds,*

*as explained in <xref target="RFC5389" />, Section 7.2.1.*
*This timeout value is chosen to roughly coincide with the maximum [...]*


On Tue, Jan 21, 2020 at 2:57 PM Yoshifumi Nishida <[e-mail]>
wrote:

>
>
> On Tue, Jan 21, 2020 at 9:25 AM Justin Uberti <[e-mail]> wrote:
>
>>
>>
>> On Mon, Jan 20, 2020 at 10:42 PM Yoshifumi Nishida <[e-mail]>
>> wrote:
>>
>>> Hi Justin,
>>>
>>> Thanks for the response.
>>> I put my comments in lines.
>>>
>>> On Sun, Jan 19, 2020 at 7:06 PM Justin Uberti <[e-mail]>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Sun, Jan 19, 2020 at 12:56 AM Yoshifumi Nishida via Datatracker <
>>>> [e-mail]> wrote:
>>>>
>>>>> Reviewer: Yoshifumi Nishida
>>>>> Review result: Almost Ready
>>>>>
>>>>> This document has been reviewed as part of the transport area review
>>>>> team's
>>>>> ongoing effort to review key IETF documents. These comments were
>>>>> written
>>>>> primarily for the transport area directors, but are copied to the
>>>>> document's
>>>>> authors and WG to allow them to address any issues raised and also to
>>>>> the IETF
>>>>> discussion list for information.
>>>>>
>>>>> When done at the time of IETF Last Call, the authors should consider
>>>>> this
>>>>> review as part of the last-call comments they receive. Please always CC
>>>>> [e-mail] if you reply to or forward this review.
>>>>>
>>>>> Summary:
>>>>>    This document is straightforward and almost ready for publication,
>>>>>    but it will be better to clarify the following points.
>>>>>
>>>>> 1: How to calculate the PAC timer is not very clear to me.
>>>>>    Does this draft recommend to use the equation described in Section
>>>>> 14.3 of
>>>>>    RFC8445 or are there other ways? I think this would be better to be
>>>>>    clarified.
>>>>>
>>>>
>>>> Yes, the equation in 14.3 coupled with the STUN backoff guidance in
>>>> https://tools.ietf.org/html/rfc5389#section-7.2, although these values
>>>> are just recommendations. The point here is to say that whatever is used
>>>> for the check timeouts should also be used for the PAC timer.
>>>>
>>>
>>> Right. I was just wondering that it might be useful to mention the
>>> recommended value can be calculated from the equation.
>>> If the readers know what'll be the recommandation value, I think they
>>> can have some ideas about whether their values are conservative or
>>> aggressive.
>>>
>>>
>>>>
>>>>> 2: I presume this draft only focuses on UDP candidates, but I think
>>>>> clarifying
>>>>> it would be useful.
>>>>>    I am also wondering how to treat PAC timer if agents have a mix of
>>>>> TCP and
>>>>>    UDP candidates.
>>>>>
>>>>
>>>> The guidance here applies to both UDP and TCP candidates. It would not
>>>> be unheard of for a server to only offer TCP candidates, and the client to
>>>> offer zero candidates, as in S 3.1.
>>>>
>>>
>>> I see. But, in this case, will there be a need to update RFC6544?
>>> Also, if we set PAC timer around 500 msec but establishing a TCP
>>> connection takes longer than it, should it be considered failed or not?
>>>
>>> Given RTO floor of 500 ms and exponential backoff per 5389, the PAC
>> timer will typically be around 30 seconds. Perhaps a note to this effect
>> would clarify this and point #1.
>>
>
> Sounds like an idea. I think it will be useful for readers to add a note
> for it.
> Thank you so much.
> --
> Yoshi
>
>
>