Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-for-ntp-18.txt

[Watson Ladd <[e-mail]>]

On Tue, Apr 23, 2019 at 12:32 PM Marcus Dansarie <[e-mail]> wrote:
>
>
> Thanks for your comments! See my comments inline.
>
> Kind regards,
> Marcus
>
>
> On 2019-04-22 10:06, Hal Murray wrote:
> >
> > Typo, page 20:
> >   Duplicate "Nonetheless, "
>
> Thanks! (I submitted a pull request for this last Wednesday.)
>
> >
> > Page 6, single round trip
> >   That's after the TLS setup.  Right?  How many round trips does that take?
>
> Correct, that's one round trip excluding the TLS setup. The setup is
> expected to take two or three round trips depending on version.
> (Theoretically, PSK could bring this down to one round trip, but I do
> not envisage it being used in this application.)
>
> > Page 13: cookies
> >   Do all cookies have to have the same length?
>
> It is not explicitly required by the draft. I can't see any "sane"
> reason for a server to send cookies of different length in the same reply.
>
> A practical reason for changing cookie length is if a server updates its
> (implementation dependent) cookie format. It could then start replying
> with cookies of different length than before. This could possibly create
> problems if the new cookies are longer than the old ones. To avoid
> sending replies that are longer than the requests, the server would have
> to send zero new cookies as reply to requests containing only one cookie
> placeholder in the hope that the client's next request contains two
> cookie placeholders, thus enabling it to send one cookie back.
> Hopefully, as the old cookies are depleted the client then starts
> sending larger cookie placeholder records.
>
I do not read 5.7 as encouraging using multiple cookie placeholder
fields to send a single cookie back. I actually misread the
specification and thought it required the cookie extension to be
longer then the cookie sent in response. Perhaps this should be
rewarded to encourage the server to send the minimum of {1+cookies
requested, 1+number of cookies that fit in total length of cookie
placeholder fields}.