Issue with NTP Server Synchronization - Clock Unsynchronized

[Purnimayeggina]

Issue Description:
Our NTP configuration is based on the guidelines provided in the SONiC documentation https://github.com/sonic-net/SONiC/blob/master/doc/ntp/ntp-design.md
Facing issue in synchronizing the NTP server with the client on our system. This problem was identified when reviewing the NTP logs, which indicated a time error, specifically stating that the clock is unsynchronized.

Output of show ntp:

NTP Status Details:
Output of ntpq -p server ip_address

command used to generate the NTP logs:
sudo journalctl -u ntp

Logs:

Jun 19 01:40:35 sonic ntpd[12168]: proto: precision = 0.098 usec (-23)
Jun 19 01:40:35 sonic ntpd[12168]: basedate set to 2019-08-28
Jun 19 01:40:35 sonic ntpd[12168]: gps base set to 2019-09-01 (week 2069)
Jun 19 01:40:35 sonic ntpd[12168]: restrict 0.0.0.0: KOD does nothing without LIMITED
Jun 19 01:40:35 sonic ntpd[12168]: Listen normally on 0 lo 127.0.0.1:123
Jun 19 01:40:35 sonic ntpd[12168]: Listen normally on 1 eth0 172.30.25.103:123
Jun 19 01:40:35 sonic ntpd[12168]: Listening on routing socket on fd #18 for interface updates
Jun 19 01:40:35 sonic ntpd[12168]: kernel reports TIME_ERROR: 0x41: Clock Unsynchronized
Jun 19 01:40:35 sonic ntpd[12168]: kernel reports TIME_ERROR: 0x41: Clock Unsynchronized
Jun 19 01:40:35 sonic ntp-systemd-wrapper[12162]: Starting NTP server in default-vrf: ntpd
Jun 19 01:40:35 sonic systemd[1]: Started Network Time Service.

Additional Information:

All necessary services (ntp, hostcfgd, ntp-config) have been confirmed to be running.
The server ip address is reachable via ping.

Expected Outcome:

Successful synchronization with the configured NTP server.

I am seeking community assistance to identify any potential misconfigurations or issues that may be causing the problem.

[gechiang]

Seeking help from community who may be familiar with NTPO server config to provide recommendations..

[brholmes1]

I haven't been able to fully dig through the issue, but it may be related to how /etc/ntp.conf is being generated. The switch I am testing on does not have a management interface (eth0) and even after adding Loopback0 with an IP it does not work as described in the NTP template.

As a workaround, I was able to manually update the source interface in the config. That seems to do the trick and allows NTP to sync.

cat /etc/sonic/config_db.json | jq .NTP
{
  "global": {
    "admin_state": "enabled",
    "authentication": "disabled",
    "dhcp": "enabled",
    "server_role": "disabled",
    "src_intf": "Vlan1000",
    "vrf": "default"
  }
}

[anamehra]

On our chassis, when I looked at /etc/ntpsec/ntp.conf, the server config was missing. Looks like based on the sonic-mgmgt generated minigraph, some if checks in ntp.conf.j2 did not satisfy the addition of server config.
The changes in PR #18736 helped fix this issue for us.
From sonic-mgmt, I am trying to figure out how we can set the config like iburst which is required to speed up clock sync. Without that, it takes around 1.5 to 2 mins on our chassis to sync the clock.