[ntp:questions] Synchronize clocks without a reference clock

Spoon devnull at localhost.com
Thu Mar 22 08:56:15 UTC 2007

Steve Kostecke wrote:
> Spoon wrote:
>> Richard B. gilbert wrote:
>>> That will cause ntpd to serve the local clock.   You can, instead, use 
>>> something called orphan mode in which several machines agree on a 
>>> common, but not necessarily correct, time.
> The documentation, at
> http://www.ee.udel.edu/~mills/ntp/html/manyopt.html#orphan, says nothing
> about orphan mode providing a way for serveral hosts to agree on
> anything.
> Orphan mode provides a way for a group of hosts to choose a "leader"
> from their ranks (i.e. the group of orphans). The criteria used for
> selection is the orphan root delay, which is determined randomly at
> start-up.
>> As far as I understand, orphan mode works through broadcast, correct?
>> If I have a pair of computers A and B in different subnets, and they can 
>> only talk to each other, then my only option is to configure A to serve 
>> its local clock, and B as a client of A. Is that correct?
> "Orphan mode is intended to replace the need for the local clock driver.
> It operates in subnet configurations in ALL MODES, INCLUDING BROADCAST,
> and multiple servers and clients and handles seamless switching as
> primary sources fail and recover."

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 participants are identically configured both 
as broadcast client and as broadcast server. One or more participants 
are configured to use an outside source, either a reference clock or 
another Internet server. When the source or sources fail, the system 
stratum is set at stratum and a leader is elected to serve as the 
reference source. When an outside source of synchronization is again 
available, the orphan mode is disabled.

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

Assume A has IPv4 address
Assume B has IPv4 address
(i.e. they 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.

Could someone provide the configuration files for A and B to enable 
orphan mode?


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