NTP Server – Time Synchronization of LAN Machines to GPS NTP Server

ntp

I have 4 computers on a LAN that need to have their system clocks closely synchronized within a ms or so if possible. I have just installed a GPS based time server (ESE-104A) on the LAN. At this point the LAN is connected to a router and the internet but the router will not be connected to the internet when operational.

In operation the whole system will be started when power is applied to the machines, NTP server, and router.

  1. How can I set Ubuntu to sync every so many minutes and calculate what the period should be?

  2. How can I get an idea of how long it takes to settle down and what the quality of the time keeping is?

  3. I found a reference, from around 2000 perhaps, that suggests that the hwclock should be synched from the system time only at shut down. Should I do this and how?

  4. What log files should I keep?

Here's the results of "ntpq –

    remote   refid       st t when poll reach   delay   offset  jitter
    *nts   .M-@M-(^AM-R.  1 u  29  128   377    38.912  -7.739   7.195

Here's my ntp.conf (I use IPv4 only)

    driftfile /etc/ntp.drift

    statistics loopstats peerstats clockstats
    filegen loopstats file loopstats type day enable
    filegen peerstats file peerstats type day enable
    filegen clockstats file clockstats type day enable

    server 192.168.1.210

    restrict -4 default kod notrap nomodify nopeer noquery
    restrict -6 default kod notrap nomodify nopeer noquery

    restrict 127.0.0.1
    restrict ::1

Best Answer

Run ntpd on all machines. Set the server so that it gets its time from the gps receiver and point the other machines to the server. With iburst the clients will sync fast enough for your purposes.

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