[ntp:questions] picking a system peer

David Newman dnewman at networktest.com
Sat Aug 18 00:04:35 UTC 2007


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Thanks for answers on my earlier question on getting set up with a GPS
receiver.

Next issue: ntpd consistently does not pick the local GPS receiver as
system peer and instead locks in on another server with higher delay and
stratum.

Here is my ntp.conf:

# ntp.conf

server 127.127.26.0
server timekeeper.isi.edu
server t1.timegps.net
server t2.timegps.net
server hydrogen.cert.ucr.edu iburst
server clock.develooper.com iburst

restrict 207.181.8.128 mask 255.255.255.192 nomodify notrap

driftfile /var/db/ntp.drift

# eof

The first server is my GPS receiver. The next three are open stratum 1
servers. The final two are open stratum 2 servers.

After ntpd has run for around 24 hours, ntpq -p looks like this:

mail# ntpq -p
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
xGPS_HP(0)       .GPS.            0 l   11   64  377    0.000  947.161
 3.081
+timekeeper.isi. .GPS.            1 u  845 1024  237   61.107   -4.727
 7.175
+cpe-76-168-23-8 .GPS.            1 u   67 1024  377   34.322   -3.144
 1.387
*cpe-76-169-239- .GPS.            1 u  103 1024  377   29.793    0.814
 3.152
- -hydrogen.cert.u 216.218.254.202  2 u   57 1024  377   14.689   -3.012
 4.311
- -clock-b.develoo 10.0.201.116     2 u 1021 1024  377   18.789   -3.747
 0.439

Per the ntpq manpage I believe "x" means "the peer is discarded."

I don't know why, and would strongly prefer that my clients use it
because it's local.

Is a "prefer" statement what I want? And what's with that big offset?

Thanks in advance for clues in understanding why a local time source
doesn't get selected as the system peer.

This is for ntpd 4.2.2p3 on FreeBSD 6.2-RELENG on i386.

dn

ps. If I stop ntpd and query the GPS receiver via serial, it passes all
its health checks and otherwise looks to be OK.
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