[ntp:questions] Synchronize clocks without a reference clock

Steve Kostecke kostecke at ntp.isc.org
Thu Mar 22 13:00:56 UTC 2007

On 2007-03-22, Spoon <devnull at localhost.com> wrote:

> The documentation also states:
> tos orphan stratum
>      If stratum is set at some value less than 16 a special orphan mode 
> is enterred when no outside source of synchronization is available. To 
> use orphan mode a number of

Here's the configuration you need:

> [1.] participants are identically configured both as broadcast client
> and as broadcast server.

This means you have to add the following configuration directives to the
ntp.conf for _each_ participant:

	broadcast <broadcast_address> <authentication>

And you have to either (a) disable authentication or (b) configure
symmetric keys or (c) configure autokey. If you use symmetric keys
<authentication> will be 'key N'; where N is the shared key number.
If you use Autokey <authentication> will be 'autokey'

> [2.] One or more participants are configured to use an outside source,
> either a reference clock or another Internet server.

With the usual server lines.

Plus each participant will also need the 'tos orphan N' line,
'driftfile', etc.,

> It is not clear to me how the two computers from my example find each
> other.

The broadcast clients (i.e. all the participants) are listening on for
the broadcast servers (i.e. all the participants) on the broadcast

> ([A and B] are not in the same subnet)
> One or several routers forward packets to/from these two subnets.
> Broadcast traffic is not forwarded by the routers.

That would rule out the use of ophan mode.

Steve Kostecke <kostecke at ntp.isc.org>
NTP Public Services Project - http://ntp.isc.org/

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