Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007, Руководство по установке

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32.2 Configuring xntp in the Network
The easiest way to use a time server in the network is to set server parameters. For ex-
ample, if a time server called
ntp.example.com
is reachable from the network, add
its name to the file
/etc/ntp.conf
by adding the line
server
ntp.example.com
. To add more time servers, insert additional lines with the key-
word
server
. After initializing xntpd with the command
rcntpd start
, it takes
about one hour until the time is stabilized and the drift file for correcting the local
computer clock is created. With the drift file, the systematic error of the hardware clock
can be computed as soon as the computer is powered on. The correction is used imme-
diately, resulting in a higher stability of the system time.
There are two possible ways to use the NTP mechanism as a client: First, the client can
query the time from a known server in regular intervals. With many clients, this approach
can cause a high load on the server. Second, the client can wait for NTP broadcasts sent
out by broadcast time servers in the network. This approach has the disadvantage that
the quality of the server is unknown and a server sending out wrong information can
cause severe problems.
If the time is obtained via broadcast, you do not need the server name. In this case, enter
the line
broadcastclient
in the configuration file
/etc/ntp.conf
. To use one
or more known time servers exclusively, enter their names in the line starting with
servers
.
32.3 Setting Up a Local Reference
Clock
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 IP addresses. 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 the unit, which determines the interface used.
Time Synchronization with NTP 607