Undisciplined Local Clock

Author: David L. Mills (mills@udel.edu)
Last update: 29-Nov-2012 16:51 UTC


Synopsis

Address: 127.127.1.u
Reference ID: LOCL
Driver ID: LOCAL

Description

Not: This driver is not recommended for new installations. A much more flexible replacement is described on the Orphan Mode page.

This driver is 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 (Digital machines are good, Sun machines are not) 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.

Monitor Data

No filegen clockstats monitor data are produced by this driver.

Fudge Factors

time1 time
Specifies the time offset calibration factor, in seconds and fraction, with default 0.0.
time2 time
Specifies the frequency offset calibration factor, in parts per million, with default 0.0.
stratum number
Specifies the driver stratum, in decimal from 0 to 15, with default 5.
refid string
Specifies the driver reference identifier, an ASCII string from one to four characters, with default LOCL.
flag1 0 | 1
Not used by this driver.
flag2 0 | 1
Not used by this driver.
flag3 0 | 1
Not used by this driver.
flag4 0 | 1
Not used by this driver.

Additional Information

Reference Clock Drivers