The software package xntp contains
drivers for connecting local reference clocks. A list of supported clocks
is available in the xntp-doc
package
in the file
/usr/share/doc/packages/xntp-doc/html/refclock.htm
.
Every driver is associated with a number. In xntp,
the actual configuration takes place by means of pseudo IPs. The
clocks are entered in the file /etc/ntp.conf
as though they existed in the network.
For this purpose, they are assigned special IP addresses in the form
127.127.t.u
.
Here, t
stands for the
type of the clock and determines which driver is used
and u
for unit, which determines the interface used.
Normally, the individual drivers have special parameters that
describe configuration details.
The file
/usr/share/doc/packages/xntp-doc/html/driverNN.htm
(where NN
is the number of the driver)
provides information about the particular type of clock.
For example, the “type 8” clock
(radio clock over serial interface)
requires an additional mode that specifies the clock more precisely.
The Conrad DCF77 receiver module, for example, has mode 5.
To use this clock as a preferred reference, specify the
keyword prefer
.
The complete server
line for a Conrad DCF77
receiver module would be:
server 127.127.8.0 mode 5 prefer
Other clocks follow the same pattern. Following the installation of the
xntp-doc
package, the
documentation
for xntp is available in the directory
/usr/share/doc/packages/xntp-doc/html
.
The file
/usr/share/doc/packages/xntp-doc/html/refclock.htm
provides links to the driver pages describing the driver parameters.