Datasheet

“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 527 — #553
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21
Linux in the Network
To add further time servers, insert additional lines with the keyword
server. After initializing xntpd with the command rcxntpd start, it
takes one hour until the time is stabilized and the “drift” file for correcting
the local computer clock is created. In the long run, the advantage of the
“drift” file is that the drift of the hardware clock can be projected as soon
as the computer is powered on. The correction is activated immediately,
resulting in a high stability of the computer time.
If the time server in your network can be reached via broadcast, you do not
need the server name. In this case, enter the command broadcastclient
in the configuration file /etc/ntp.conf. To avoid an incorrect time server
in the network from changing the computer time, set up the authentication
mechanisms.
Normally, every xntpd in the network can also be addressed as time server.
To run xntpd with broadcasts, configure the broadcast option:
broadcast 192.168.0.255
Adjust the broadcast address to your circumstances. Make sure the time
server uses the correct time. This can be done with reference clocks.
21.12.2 Setting up a Local Reference Clock
The software package xntp also contains drivers for connecting local ref-
erence 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.hti.hui. Refer to the above-mentioned file containing the list
of reference clocks to get the value for hti. hui is the device number that is
only higher than 0 if you use several clocks of the same type on the com-
puter. For example, a “Type 8 Generic Reference Driver (PARSE)” has the
pseudo IP address 127.127.8.0.
Normally, the individual drivers have special parameters that describe
configuration details. The file /usr/share/doc/packages/xntp-
doc/html/refclock.htm provides links to the respective driver pages
describing these parameters. For example, the “Type 8” clock requires an
additional mode that specifies the clock more precisely. For example, the
Conrad DCF77 receiver module has mode 5. To make xntp accept this clock
as a reference, specify the keyword prefer. Thus, the complete server
line for a Conrad DCF77 receiver module would be:
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SUSE LINUX Enterprise Server