[ntp:hackers] Further to the timestamping issue

TSG tglassey at earthlink.net
Wed Jun 18 23:48:47 UTC 2008


Dave

----- Original Message ----- 
From: "David L. Mills" <mills at udel.edu>
To: <hackers at ntp.org>; <ntpwg at lists.ntp.org>
Sent: Tuesday, June 17, 2008 7:08 AM
Subject: Re: [ntp:hackers] Further to the timestamping issue


> Poul,
>
> It might not be clear from the documentation, as most folks might
> consider it an overly pedantic issue, but there is a serious formal
> model here. I consider three disciplined oscillators with respect to a
> primary server. First is the remote source, such as the WWV antenna.
> Second is the local reference oscillator in the GPS receiver or in the
> WWV case the audio codec. Third is the system clock disciplined by NTP.
> The device driver interface design is intended to allow contributions
> from the first two sources to be budgeted.

meaning that while the budgeted sources are weighted in how they are applied 
the OS Clock is not and this is the core problem with a Software Only Clock 
system.

I would propose that NTP doesnt really need to be tied to a SW only clock 
and in fact the NTP Server Package and not the NTP protocol is what ties it 
to a SW based clock model.

That said, it seems totally reasonable that in instances where there is an 
embedded HW based timekeeping system like a 1588MC or similar, that the NTP 
calls should be able to point to it rather than only getting time off the 
local host-based OS Clock through the local NTP Service Daemon.

Todd

> 



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