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Re: [Ntp] NTS4UPTP Rev 03 - Formal request for WG adoption

Danny Mayer <mayer@pdmconsulting.net> Tue, 01 June 2021 18:49 UTC

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To: Daniel Franke <dfoxfranke@gmail.com>
Cc: Heiko Gerstung <heiko.gerstung=40meinberg.de@dmarc.ietf.org>, Miroslav Lichvar <mlichvar@redhat.com>, NTP WG <ntp@ietf.org>
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From: Danny Mayer <mayer@pdmconsulting.net>
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Date: Tue, 01 Jun 2021 14:48:59 -0400
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Subject: Re: [Ntp] NTS4UPTP Rev 03 - Formal request for WG adoption
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That ignores the fact that you are bombarding the servers with requests 
at a very high rate. There's a very good reason why we implemented KOD 
packets. You wouldn't want to put any of those responses through a filter.

Danny

On 6/1/21 2:03 PM, Daniel Franke wrote:
> Depends on your clock discipline algorithm. Yes, if you feed an 
> excessive number of samples into a underdamped PLL then your clock is 
> just going to bounce around a lot without ever getting more accurate. 
> But e.g. a Kalman filter should happily slurp up as many samples as 
> you throw at it. Having more information can't be bad unless you use 
> it badly.
>
> On Tue, Jun 1, 2021, 13:54 Danny Mayer <mayer@pdmconsulting.net 
> <mailto:mayer@pdmconsulting.net>> wrote:
>
>     Noone should be using a polling interval that small. Oversampling
>     is as bad as undersampling.
>
>     Danny
>
>     On 6/1/21 1:28 PM, Daniel Franke wrote:
>>     It's in units of log2(seconds) so a negative value makes fine
>>     sense. E.g. -1 means half a second.
>>
>>     On Tue, Jun 1, 2021, 13:24 Danny Mayer <mayer@pdmconsulting.net
>>     <mailto:mayer@pdmconsulting.net>> wrote:
>>
>>
>>         On 6/1/21 11:42 AM, Miroslav Lichvar wrote:
>>         >
>>         > I'm not sure I follow here. You can send NTP requests at
>>         any rate you
>>         > like. That doesn't require a new protocol. The poll field
>>         is a signed
>>         > 8-bit integer if you had a server that actually looked in
>>         the content
>>         > of the field.
>>
>>         I hope not. How would you implement a negative poll interval? :)
>>
>>         It really should be unsigned. If not, then that's really an
>>         error.
>>
>>         Danny
>>
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