NTP client does not synchronize with peer servers operating in tos orphan mode

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Environment

SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 12

Situation

NTP clients connecting to a specified peer operating in tos orphan mode will not synchronize but use the local clock instead.
The client /etc/ntp.conf contains a tos orphan mode entry as well.

Resolution

Please remove the tos orphan option from /etc/ntp.conf and restart the client.

Cause

Tests have shown that clients might enter a condition where they consider themselves as the leader of the peer and not sync with other servers. In tos orphan mode it is common for the leader of the peer to show sync_unspec and refid=127.0.0.1 as timesource.

Additional Information

Details about the NTP tos orphan option are available in the NTP documentation: http://support.ntp.org/bin/view/Support/OrphanMode

This is an example output of an elected leader of a four node ntp peer operating in tos orphan mode.
Here the sync status is displayed as sync_unspec and refid points to 127.0.0.1 indicating the local clock is used.

ntp1:~ # ntpq -p -c rv
     remote           refid      st t when poll reach   delay   offset jitter
==============================================================================
ntp1.test.lan .INIT.          16 s    -   64    0    0.000    0.000   0.000
ntp2.test.lan 192.168.66.147   9 s   18   64 376    0.127   -0.011   0.016
ntp3.test.lan 192.168.66.147   9 s   42   64 376    0.140   -0.005   0.006
ntp4.test.lan 192.168.66.147   9 s   17   64 377    0.125   -0.008   0.011
associd=0 status=0016 leap_none, sync_unspec, 1 event, restart,
version="ntpd 4.2.8p10@1.3728-o Tue Mar 28 09:22:06 UTC 2017 (1)",
processor="x86_64", system="Linux/3.0.101-100-default", leap=00,
stratum=8, precision=-23, rootdelay=0.000, rootdisp=0.000,
refid=127.0.0.1,
reftime=00000000.00000000 Thu, Feb 7 2036 7:28:16.000,
clock=dd2d77e0.f382ea17 Thu, Aug 3 2017 12:22:24.951, peer=0, tc=3,
mintc=3, offset=0.000000, frequency=0.000, sys_jitter=0.000000,
clk_jitter=0.000, clk_wander=0.000

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