proposed Local_Clock doc change - Externally Disciplined
mlewis000 at rogers.com
Tue Nov 28 22:31:28 UTC 2017
Note: We recommend against using this driver. A much more flexible
replacement is described on the Orphan Mode page.
This driver was intended for use in an isolated network where no
external source of synchronization such as a radio clock or modem is
available. It allows a designated time server to act as a primary server
to provide synchronization to other clients on the network. Pick a
machine that has a good clock oscillator and configure it with this
driver. Set the clock using the best means available, like
eyeball-and-wristwatch. Then, point all the other machines at this one
or use broadcast mode to distribute time.
Another application for this driver is if a particular server clock is
to be used as the clock of last resort when all other normal
synchronization sources have gone away. This is especially useful if
that server has an ovenized oscillator. For this you would usually, but
not necessarily, configure this driver at a stratum greater than any
other likely sources of time, such as the default 5 for this driver, to
prevent this driver taking over when legitimate sources elsewhere in the
network are available. To further protect the Internet infrastructure
from accidental or malicious exposure to this driver, the driver is
disabled if another source is available and operating.
Proposed draft of a new paragraph to add to the above description.
This driver is used when the system clock is Externally Disciplined (not
disciplined/adjusted by NTP) and the system clock needs to be available
to NTP so the externally disciplined system clock can be provided to
NTP-Clients. For example, when the system clock is externally
disciplined by: Precision Time Protocol (PTP), a high resolution counter
disciplined by a GPS receiver, the Digital Time Synchronization Service
(DTSS), or a completely separate clock discipline algorithm and
synchronization protocol, such as the Lockclock algorithm used with NIST
Automated Computer Time Service (ACTS) modem synchronized time. See
https://docs.ntpsec.org/latest/extern.html for more information.
More information about the devel