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Re: [Ntp] WGLC: draft-ietf-ntp-using-nts-for-ntp

Ragnar Sundblad <ragge@netnod.se> Sun, 16 December 2018 12:44 UTC

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From: Ragnar Sundblad <ragge@netnod.se>
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Date: Sun, 16 Dec 2018 13:44:49 +0100
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To: Miroslav Lichvar <mlichvar@redhat.com>
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Subject: Re: [Ntp] WGLC: draft-ietf-ntp-using-nts-for-ntp
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Hi Miroslav,

> On 6 Dec 2018, at 13:16, Miroslav Lichvar <mlichvar@redhat.com> wrote:
> 
> In 5.7 there is "In that case, it MUST be able to detect and stop
> looping between the NTS-KE and NTP servers.". This could be explained
> in a more detail. The detection here means that the client should
> check if there were no good NTP packets received between NTS-KE
> exchanges?

Very good catch, thanks!

The main issue is to not overload the KE server, and that should apply
wether or not one or a few NTP transactions actually has worked or not.

The problem also may be a temporary error in the server end, so the client
actually should retry every now and then.

I believe we should replace the current:
"In that case, it MUST be able to detect and stop looping between the
NTS-KE and NTP servers.”
with something like:
“In that case, the client MUST be able to prevent fast looping between
the NTS-KE and NTP servers by rate limiting the retries using e.g.
exponentially increasing retry intervals.”

Maybe we should also add something about a recommended lower and upper
limits on the retry interval, like 30 seconds to 6 hours or so.
Or maybe we shouldn’t.

I’d be happy to share your thoughts on this!

Best regards,

/ragge

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