NTP connection fail due of failed validity test

VRP (R) software, Version 8.100 (NE20E V800R007C10SPC100)
HUAWEI NE20E-S2F uptime is 24 days, 14 hours, 19 minutes

There is problem with ntp synchronization, the error returned refers to standard test failure.

<NE20>dis current-configuration | i ntp
ntp-service ipv6 server disable
ntp-service refclock-master 2
ntp-service sync-interval 180
ntp-service source-interface LoopBack10
ntp-service unicast-server 1.1.1.1

<NE20>dis ntp-service sessions
clock source: 127.127.1.0
clock stratum: 1
clock status: configured, master, sane, valid
reference clock ID: LOCAL(0)
reach: 255
current poll: 64
now: 56
offset: 0.0000 ms
delay: 0.00 ms
disper: 1.21 ms

clock source: 1.1.1.1
clock stratum: 3
clock status: configured, insane, invalid
reference clock ID: 1.1.1.1
reach: 255
current poll: 64
now: 2
offset: 0.0000 ms
delay: 0.00 ms
disper: 0.00 ms

The server ntp is reachable:

<NE20>ping 1.1.1.1
  PING 1.1.1.1: 56  data bytes, press CTRL_C to break
    Reply from 1.1.1.1: bytes=56 Sequence=1 ttl=59 time=6 ms
    Reply from 1.1.1.1: bytes=56 Sequence=2 ttl=59 time=6 ms
    Reply from 1.1.1.1: bytes=56 Sequence=3 ttl=59 time=6 ms
    Reply from 1.1.1.1: bytes=56 Sequence=4 ttl=59 time=6 ms
    Reply from 1.1.1.1: bytes=56 Sequence=5 ttl=59 time=7 ms

  --- 1.1.1.1 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 6/6/7 ms

<NE20>dis ntp-service statistics packet
NTP IPv4 Packet Statistical Information
--------------------------------------------------
Sent                                  :      13648
    Send failures                      :          0
Received                              :      13695
    Processed                          :       6338
    Dropped                            :       7357
       Validity test failures          :       7304
          Authentication failures      :          0
       Invalid packets                 :         53
       Access denied                   :          0
       Rate-limited                    :          0
       Processing delay                :          0
       Interface disabled              :          0
       Max dynamic association reached :          0
       Server disabled                 :          0
       Others                          :          0
Last 10 packets drop reasons:
   [2016-10-26 11:30:35+01:00] From Peer 1.1.1.1 (Local mode: client/configured) Standard TEST failure.
   [2016-10-26 11:30:37+01:00] From Peer 1.1.1.1 (Local mode: client/configured) Standard TEST failure.
   [2016-10-26 11:31:42+01:00] From Peer 1.1.1.1 (Local mode: client/configured) Standard TEST failure.

We decide to perform a debugging:

<NE20>debugging ntp-service validity                                   
<NE20>t d                                                              
Info: Current terminal debugging is on.                                        
<NE20>t m                                                              
Info: Current terminal monitor is on.                                          
<NE20>  

Wait for at least 2 minutes for validity test to run. Collect the output and send it to me.

To disable debugging
<NE20>   u t d
<NE20>   u t m

And after debug system returned the following log:

Nov 15 2016 15:13:22.234+01:00 00-SWIN00_1RM_backup
%%01NTP/7/NTP_DEBUG_VALIDITY(d):VS=Admin-VS-CID=0x80260400; NTP: packet from
192.168.111.234, failed validity tests 0x00000040

The error refers to clock stratum value. As NE20E-S2F configured as local NTP server and local clock stratum value is lower than external clock source, If the local clock stratum value is lower than or the same as that of the clock source provided by the clock server, the device takes the value of the local clock. The solution will be to modify the local clock stratum value higher than external clock server, or disable NTP server on this NE20E-S2F.

The solution will be to modify the local clock stratum value higher than external clock server, or disable NTP server on this NE20E-S2F.

[~HUAWEI] ntp-service refclock-master x     /// x depending on Linux server stratum value, the maximum value is 15.
or
[~HUAWEI] ntp-service server disable

none.