Ntp Clock is unsynchronized in 3850

[m.abdulsami]

Hi, i was facing an issue with NTP sync in 3850 switch

Show ntp status

Clock is unsynchronized, stratum 16, no reference clock 

sh ntp associations

address ref clock st when poll reach delay offset disp
~172.16.143.252 .TIME. 16 - 64 0 0.000 0.000 15937.
~172.16.143.253 .TIME. 16 - 64 0 0.000 0.000 15937.
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

as i see in debug command 

NTP Core(INFO): 172.16.143.252 8015 85 restart timeout
May 16 09:53:22.809 AST: NTP: ntpio_send_ipv4: dst 172.16.143.252, src 0.0.0.0, if_out Vlan2
May 16 09:53:22.809 AST: NTP message sent to 172.16.143.252, from interface 'Vlan2' (172.16.143.21).

NTP: ntpio_send_ipv4: dst 172.16.143.253, src 0.0.0.0, if_out Vlan2
May 16 09:54:11.809 AST: NTP message sent to 172.16.143.253, from interface 'Vlan2' (172.16.143.21).

[MHM Cisco World]

check my other comment 

[balaji.bandi]

can you post below output :

show run | in ntp

show ntp config

show ntp associations details

traceroute 172.16.143.253 using source vlan2

show ip route

[m.abdulsami]

Thanks @balaji.bandi 

RH-F2C1-AS01#sh ntp config
ntp server 172.16.143.252
ntp server 172.16.143.253
RH-F2C1-AS01#sh run | in ntp
10 permit udp any any eq ntp
20 permit udp any eq ntp any
ntp authentication-key 1 md5 13544246595D5D78087179 7
ntp authenticate
ntp trusted-key 1
ntp source Vlan2
ntp server 172.16.143.252
ntp server 172.16.143.253

RH-F2C1-AS01#sh ntp associations detail
172.16.143.252 configured, ipv4, insane, invalid, unsynced, stratum 16
ref ID .INIT., time 00000000.00000000 (03:00:00.000 AST Mon Jan 1 1900)
our mode client, peer mode unspec, our poll intvl 64, peer poll intvl 1024
root delay 0.00 msec, root disp 0.00, reach 0, sync dist 15937.79
delay 0.00 msec, offset 0.0000 msec, dispersion 15937.50, jitter 0.00 msec
precision 2**10, version 4
assoc id 26793, assoc name 172.16.143.252
assoc in packets 0, assoc out packets 6, assoc error packets 0
org time E81336DB.50A3D7E8 (15:08:59.315 AST Sat May 20 2023)
rec time 00000000.00000000 (03:00:00.000 AST Mon Jan 1 1900)
xmt time 00000000.00000000 (03:00:00.000 AST Mon Jan 1 1900)
filtdelay = 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
filtoffset = 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
filterror = 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0
minpoll = 6, maxpoll = 10

172.16.143.253 configured, ipv4, insane, invalid, unsynced, stratum 16
ref ID .INIT., time 00000000.00000000 (03:00:00.000 AST Mon Jan 1 1900)
our mode client, peer mode unspec, our poll intvl 64, peer poll intvl 1024
root delay 0.00 msec, root disp 0.00, reach 0, sync dist 15937.71
delay 0.00 msec, offset 0.0000 msec, dispersion 15937.50, jitter 0.00 msec
precision 2**10, version 4
assoc id 26794, assoc name 172.16.143.253
assoc in packets 0, assoc out packets 6, assoc error packets 0
org time E81336E1.52F1AAE0 (15:09:05.324 AST Sat May 20 2023)
rec time 00000000.00000000 (03:00:00.000 AST Mon Jan 1 1900)
xmt time 00000000.00000000 (03:00:00.000 AST Mon Jan 1 1900)
filtdelay = 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
filtoffset = 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
filterror = 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0
minpoll = 6, maxpoll = 10

RH-F2C1-AS01#traceroute 172.16.143.252 source vlan 2
Type escape sequence to abort.
Tracing the route to rh-fgc2-ds01 (172.16.143.252)
VRF info: (vrf in name/id, vrf out name/id)
1 rh-fgc2-ds01.kfmc.med (172.16.143.252) 2 msec * 2 msec
RH-F2C1-AS01#traceroute 172.16.143.253 source vlan 2
Type escape sequence to abort.
Tracing the route to rh-fgc2-ds02 (172.16.143.253)
VRF info: (vrf in name/id, vrf out name/id)
1 rh-fgc2-ds02.kfmc.med (172.16.143.253) 2 msec * 2 msec

[MHM Cisco World]

ntp server 172.16.143.252 key1  <<- I found the issue after make second review of config 
ntp server 172.16.143.253 key1 

[jmcgrady1]

Further to OP:

address ref clock st when poll reach delay offset disp
~172.16.143.252 .TIME. 16 - 64 0 0.000 0.000 15937.
~172.16.143.253 .TIME. 16 - 64 0 0.000 0.000 15937.

Its curious that your time sources are listed as stratum 16. Is that correct?  One standard says the switch cant be an NTP source if its own sources are greater than stratum 15.

[Rich R]

@jmcgrady1 that's just because they're not synchronised (reason for that explained in the solution - NTP packets being blocked).  16 = "insane" so is not a valid source.

You can see from the other output provided above that the two sources are stratum 3, both from another client of theirs and from the nodes themselves:

RH-FGC1-AS01#sh ntp associations
address ref clock st when poll reach delay offset disp
+~172.16.143.252 172.20.254.244 3 1009 1024 377 1.000 2.500 2.013
*~172.16.143.253 172.20.254.244 3 157 1024 377 1.000 0.500 2.029
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured