[time-nuts] NTP stratum 0

Magnus Danielson cfmd at bredband.net
Sat Jan 14 11:59:22 EST 2006


From: Neal McBurnett <neal at mcburnett.org>
Subject: Re: [time-nuts] NTP stratum 0
Date: Sat, 14 Jan 2006 09:45:21 -0700
Message-ID: <20060114164520.GA25156 at feynman>

> On Sat, Jan 14, 2006 at 05:25:04PM +0100, TwoSpades wrote:
> > I would like to know where could I find the FORMAL specification of the NTP
> > stratum 0.
> > I often read that it can be a GPS receiver, but I think that there must be a
> > formal definition
> > of the characteristics of that device.
> 
> The Internet Engineering Task Force (IETF) does a great job of making this
> stuff available to the general public, especially when compared to the
> ITU or ISO standards.
> 
> NTP is documented in RFC1305:
>  http://www.potaroo.net/ietf/idref/rfc1305/
> 
> And SNTP in RFC2030:
>  http://www.potaroo.net/ietf/idref/rfc1305/
> 
> Note that the IETF "ntp" working group is working on updating the NTP
> standard, again in a relatively refreshing and open manner:
> 
>  http://ietf.org/html.charters/ntp-charter.html
> 
> Join us and get a standard TAI spec for NTP!

With all this information (which is great BTW) you could also have answered
the specific question:

3.4  Stratum (Strat)

   This is a eight-bit unsigned integer indicating the stratum.  This
   field is significant only in SNTP server messages, where the values
   are defined as follows:

  +---------+-------------------------------------------------------+
  | Stratum |                        Meaning                        |
  +---------+-------------------------------------------------------+
  |    0    |                 kiss-o'-death message                 |
  |    1    | primary reference (e.g., synchronized by radio clock) |
  |   2-15  |   secondary reference (synchronized by NTP or SNTP)   |
  |  16-255 |                        reserved                       |
  +---------+-------------------------------------------------------+

So, Stratum 1 is as low they go or high up in the stratum chain you come.

Cheers,
Magnus



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