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23 mar 2023 · Reference clocks are identified by a syntactically correct but invalid IP address, in order to distinguish them from ordinary NTP peers. These addresses are of the form 127.127.t.u, where t is an integer denoting the clock type and u indicates the unit number in the range 0-3.
23 lis 2022 · NTP Version 4 supports almost four dozen satellite, radio and telephone modem reference clocks plus several audio devices for instrumentation signals. A general description of the reference clock support is on this page.
14 wrz 2024 · Reference clocks are identified by a syntactically correct but invalid IP address, in order to distinguish them from normal NTP peers. Reference clock addresses are of the form 127.127.t.u, where t is an integer denoting the clock type and u indicates the unit number in the range 0-3. While it may seem overkill, it is in fact sometimes useful ...
The refclock command is used to configure a reference clock. The options resemble those of the server directives, but mode, minpoll, maxpoll, and prefer options are supported for reference clocks, as described on the Reference Clock Commands page.
For most directly connected reference clocks, both minpoll and maxpoll default to 6 (64 sec). For modem reference clocks, minpoll defaults to 10 (17.1 min) and maxpoll defaults to 14 (4.5 hours). The allowable range is 0 (1 sec) to 17 (36.4 hours) inclusive.
To change the default configuration of the NTP service, use a text editor running as root user to edit the /etc/ntp.conf file. This file is installed together with ntpd and is configured to use time servers from the Red Hat pool by default.
By convention, reference clock drivers are named in the form refclock_xxxx.c, where xxxx is a unique string. Each driver is assigned a unique type number, long-form driver name, short-form driver name, and device name.