[time-nuts] NTP stratum 0
Magnus Danielson
cfmd at bredband.net
Sat Jan 14 16:59:22 UTC 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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