I have a 2960X switch NTP clock is not syncing

[naveedbaba]

I have a 2960X switch, NTP clock is not syncing, i have configured NTP server IP, but getting below error, can you please have a look and assist

Clock is unsynchronized, stratum 16, no reference clock

[M02@rt37]

Hello @naveedbaba 

add source interface on your ntp server configuration:

ntp server A.B.C.D. source <interface_source>

Check If you have Firewall also and permit udp_123 between server and client NTP

[naveedbaba]

Hello M02@rt37  Thank you for your response.

Im using one of the C9500 switch as a NTP server and below are the configurations:

sw#sh run | i ntp
ntp source Vlan254
ntp server x.x.x.x
ntp server vrf LAN x.x.x.x, 

please help me if any modifications/corrections needed.

[M02@rt37]

@naveedbaba 

Firewall on the road ?

[naveedbaba]

There is a CATO firewall but traffic is already allowed on CATO firewall, and my concern is client NTP switch also needs to sync with their NTP server?

Below are the client NTP configurations:

sw#sh ntp associations

address ref clock st when poll reach delay offset disp
~x.x.x.x .TIME. 16 - 64 0 0.000 0.000 15937.
~x.x.x.x .TIME. 16 - 64 0 0.000 0.000 15937.
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

sw#sh ntp status
Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 250.0000 Hz, actual freq is 249.9987 Hz, precision is 2**10
ntp uptime is 1129661900 (1/100 of seconds), resolution is 4016
reference time is 00000000.00000000 (02:00:00.000 EET Mon Jan 1 1900)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 169449.26 msec, peer dispersion is 0.00 msec
loopfilter state is 'FSET' (Drift set from file), drift is 0.000005231 s/s
system poll interval is 8, never updated.

[M02@rt37]

@naveedbaba 

Does your C9500 has got the NTP master command  configured ?

On CATO Firewall could you sniffer udp packet from client to NTP server ?

[M02@rt37]

@naveedbaba 

Possible to try icmp from client to ntp server.

Ping vrf LAN a.b.c.d source vlan254 

Also, provide NTP configuration on your C9500. You should have ntp master x command.

[Leo Laohoo]

---

@naveedbaba wrote:
Im using one of the C9500 switch as a NTP server

---

On the 9500, post the complete output to the command "sh ntp associate".

[naveedbaba]

Below are the client NTP configurations on 9500:

sw#sh ntp associations

address ref clock st when poll reach delay offset disp
~x.x.x.x .TIME. 16 - 64 0 0.000 0.000 15937.
~x.x.x.x .TIME. 16 - 64 0 0.000 0.000 15937.
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

sw#sh ntp status
Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 250.0000 Hz, actual freq is 249.9987 Hz, precision is 2**10
ntp uptime is 1129661900 (1/100 of seconds), resolution is 4016
reference time is 00000000.00000000 (02:00:00.000 EET Mon Jan 1 1900)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 169449.26 msec, peer dispersion is 0.00 msec
loopfilter state is 'FSET' (Drift set from file), drift is 0.000005231 s/s
system poll interval is 8, never updated.

[Leo Laohoo]

That's the reason why the 2960X is not synching NTP:  The 9500 time is not correct.  Look at it, the 9500 is a "stratum 16" (not to be trusted).

[naveedbaba]

Thank you @Leo Laohoo i have corrected the configurations, Now both client and server NTP switches are synchronized but server switch time is not yet sync with client switch, can you please suggest, please find the below configurations:

Client switch NTP configuration:

sw#sh run | i ntp
ntp source Loopback0
ntp master 10
sw#sh clock
13:42:12.108 EET Tue Sep 19 2023

Server switch NTP configuration:

sw1#sh run | i ntp
ntp server x.x.x.x

sw1#sh ntp status
Clock is synchronized, stratum 11, reference is 10.125.50.129
nominal freq is 286.1023 Hz, actual freq is 286.0971 Hz, precision is 2**19
ntp uptime is 448200 (1/100 of seconds), resolution is 3496
reference time is E8B3F7B2.3D70CBD9 (12:34:26.240 EET Tue Sep 19 2023)
clock offset is 0.4322 msec, root delay is 26.28 msec
root dispersion is 15.07 msec, peer dispersion is 1.84 msec
loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000018198 s/s
system poll interval is 256, last update was 380 sec ago.

sw1#sh ntp associations

address ref clock st when poll reach delay offset disp
*~x.x.x.x 127.127.1.1 10 249 256 377 24.951 0.432 1.846
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

sw1#sh clock
12:40:57.314 EET Tue Sep 19 2023