NTP Clock Sync for Switch - CISCO Catalyst 2960-48TT

[JforJignesh]

Hi,

Switch - CISCO Catalyst 2960-48TT - NTP time sync issue.

NTP server is Windows Server 2022 (Domain Controller).

Pls find below command output step by step for easy understanding.

CSA_SW#show clock detail
.19:28:40.268 IST Fri Dec 8 2023
Time source is NTP

CSA_SW#show ntp associations

address ref clock st when poll reach delay offset disp
~172.16.4.5 .LOCL. 1 74 1024 377 1.9 6638.9 24.9
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

CSA_SW#ping 172.16.4.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.4.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

CSA_SW#show ntp associations detail
172.16.4.5 configured, insane, invalid, stratum 1
ref ID .LOCL., time E91D9746.AF388DE6 (18:53:18.684 IST Fri Dec 8 2023)
our mode client, peer mode server, our poll intvl 1024, peer poll intvl 1024
root delay 0.00 msec, root disp 10019.42, reach 377, sync dist 10045.227
delay 1.86 msec, offset 6638.9188 msec, dispersion 24.87
precision 2**23, version 3
org time E91D9DD5.43307944 (19:21:17.262 IST Fri Dec 8 2023)
rcv time E91D9DCE.9FDD5878 (19:21:10.624 IST Fri Dec 8 2023)
xmt time E91D9DCE.9F624DC0 (19:21:10.622 IST Fri Dec 8 2023)
filtdelay = 1.86 2.33 1.75 1.68 1.68 1.91 1.62 1.80
filtoffset = 6638.92 6625.90 6613.31 6600.43 6587.45 6574.48 6561.85 6548.73
filterror = 0.02 15.64 31.27 46.89 62.52 78.14 93.77 109.39

CSA_SW#show ntp status
Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 119.2092 Hz, actual freq is 119.2092 Hz, precision is 2**17
reference time is 00000000.00000000 (05:30:00.000 IST Mon Jan 1 1900)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.00 msec, peer dispersion is 0.00 msec

Logs as below

009084: .Dec 8 13:17:02.627: xmt E91D95CE.A0971F22 (18:47:02.627 IST Fri Dec 8 2023)
009085: .Dec 8 13:17:02.627: NTP: rcv packet from 172.16.4.5 to 172.16.5.151 on Vlan164:
009086: .Dec 8 13:17:02.627: leap 0, mode 4, version 3, stratum 1, ppoll 1024
009087: .Dec 8 13:17:02.627: rtdel 0000 (0.000), rtdsp AFEE7 (10995.712), refid 4C4F434C (76.79.67.76)
009088: .Dec 8 13:17:02.627: ref E91C45C6.A9DBAC63 (18:53:18.663 IST Thu Dec 7 2023)
009089: .Dec 8 13:17:02.627: org E91D95CE.A0971F22 (18:47:02.627 IST Fri Dec 8 2023)
009090: .Dec 8 13:17:02.627: rec E91D95D5.3DD2FA0D (18:47:09.241 IST Fri Dec 8 2023)
009091: .Dec 8 13:17:02.627: xmt E91D95D5.3DD3A1D3 (18:47:09.241 IST Fri Dec 8 2023)
009092: .Dec 8 13:17:02.627: inp E91D95CE.A10B1322 (18:47:02.629 IST Fri Dec 8 2023)
009093: .Dec 8 13:17:02.627: NTP: nlist 0, allow 0, found 0, low 0.000000, high 0.000000
009094: .Dec 8 13:17:02.627: NTP: no select intersection
009095: .Dec 8 13:17:02.627: NTP: no select intersection
009096: .Dec 8 13:34:06.624: NTP: xmit packet to 172.16.4.5:
009097: .Dec 8 13:34:06.624: leap 3, mode 3, version 3, stratum 0, ppoll 1024
009098: .Dec 8 13:34:06.624: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)
009099: .Dec 8 13:34:06.624: ref 00000000.00000000 (05:30:00.000 IST Mon Jan 1 1900)
009100: .Dec 8 13:34:06.624: org E91D95D5.3DD3A1D3 (18:47:09.241 IST Fri Dec 8 2023)
009101: .Dec 8 13:34:06.624: rec E91D95CE.A10B1322 (18:47:02.629 IST Fri Dec 8 2023)
009102: .Dec 8 13:34:06.624: xmt E91D99CE.9FED5FEB (19:04:06.624 IST Fri Dec 8 2023)
009103: .Dec 8 13:34:06.624: NTP: rcv packet from 172.16.4.5 to 172.16.5.151 on Vlan164:
009104: .Dec 8 13:34:06.624: leap 0, mode 4, version 3, stratum 1, ppoll 1024
009105: .Dec 8 13:34:06.624: rtdel 0000 (0.000), rtdsp A01F0 (10007.568), refid 4C4F434C (76.79.67.76)
009106: .Dec 8 13:34:06.624: ref E91D9746.B0543BC1 (18:53:18.688 IST Fri Dec 8 2023)
009107: .Dec 8 13:34:06.624: org E91D99CE.9FED5FEB (19:04:06.624 IST Fri Dec 8 2023)
009108: .Dec 8 13:34:06.624: rec E91D99D5.4074AACC (19:04:13.251 IST Fri Dec 8 2023)
009109: .Dec 8 13:34:06.624: xmt E91D99D5.4075203D (19:04:13.251 IST Fri Dec 8 2023)
009110: .Dec 8 13:34:06.624: inp E91D99CE.A087061C (19:04:06.627 IST Fri Dec 8 2023)
009111: .Dec 8 13:34:06.624: NTP: nlist 0, allow 0, found 0, low 0.000000, high 0.000000
009112: .Dec 8 13:34:06.624: NTP: no select intersection
009113: .Dec 8 13:34:06.624: NTP: no select intersection
009114: .Dec 8 13:51:10.621: NTP: xmit packet to 172.16.4.5:
009115: .Dec 8 13:51:10.621: leap 3, mode 3, version 3, stratum 0, ppoll 1024
009116: .Dec 8 13:51:10.621: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)
009117: .Dec 8 13:51:10.621: ref 00000000.00000000 (05:30:00.000 IST Mon Jan 1 1900)
009118: .Dec 8 13:51:10.621: org E91D99D5.4075203D (19:04:13.251 IST Fri Dec 8 2023)
009119: .Dec 8 13:51:10.621: rec E91D99CE.A087061C (19:04:06.627 IST Fri Dec 8 2023)
009120: .Dec 8 13:51:10.621: xmt E91D9DCE.9F624DC0 (19:21:10.622 IST Fri Dec 8 2023)
009121: .Dec 8 13:51:10.621: NTP: rcv packet from 172.16.4.5 to 172.16.5.151 on Vlan164:
009122: .Dec 8 13:51:10.621: leap 0, mode 4, version 3, stratum 1, ppoll 1024
009123: .Dec 8 13:51:10.621: rtdel 0000 (0.000), rtdsp A04F9 (10019.424), refid 4C4F434C (76.79.67.76)
009124: .Dec 8 13:51:10.621: ref E91D9746.AF388DE6 (18:53:18.684 IST Fri Dec 8 2023)
009125: .Dec 8 13:51:10.621: org E91D9DCE.9F624DC0 (19:21:10.622 IST Fri Dec 8 2023)
009126: .Dec 8 13:51:10.621: rec E91D9DD5.432F895A (19:21:17.262 IST Fri Dec 8 2023)
009127: .Dec 8 13:51:10.621: xmt E91D9DD5.43307944 (19:21:17.262 IST Fri Dec 8 2023)
009128: .Dec 8 13:51:10.621: inp E91D9DCE.9FDD5878 (19:21:10.624 IST Fri Dec 8 2023)
009129: .Dec 8 13:51:10.621: NTP: nlist 0, allow 0, found 0, low 0.000000, high 0.000000
009130: .Dec 8 13:51:10.621: NTP: no select intersection
009131: .Dec 8 13:51:10.621: NTP: no select intersection

Can anyone tell where I am doing wrong?

Thanx in advance.

Jignesh Patel

[M02@rt37]

@JforJignesh 

Thanks for that output.

Do you ping ntp server with the source vlan164 ?

1990 ? Beacuse switch ntp is unsynchronised...

[JforJignesh]

Of course it ping

CSA_SW#ping 172.16.4.5

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.4.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/4/9 ms
CSA_SW#

[M02@rt37]

OK @JforJignesh 

Ensure that ping is sourcing with vlan 164

[JforJignesh]

What exactly mean "ping source with vlan 164?"

What is the command to be used to ping through VLAN 164?

[M02@rt37]

@JforJignesh 

CSA_SW#ping 172.16.4.5 source vlan 164

[JforJignesh]

Yes its pinging, but still clock is not synchronized. 

CSA_SW#ping 172.16.4.5 source vlan 164

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.4.5, timeout is 2 seconds:
Packet sent with a source address of 172.16.5.151
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms

[MHM Cisco World]

MHM

[MHM Cisco World]

you use Win Server not network device 
this bug is exactly what you face check 
flagged as "insane, invalid". The "root dispersion" value
https://bst.cisco.com/quickview/bug/CSCed13703

check the workaround 
MHM

[JforJignesh]

I do not understand the information provided under this link.

Not able to understand what is the action point in that link.

[MHM Cisco World]

this your output 
CSA_SW#show ntp associations detail
172.16.4.5 configured, insane, invalid, stratum 1
ref ID .LOCL., time E91D9746.AF388DE6 (18:53:18.684 IST Fri Dec 8 2023)

our mode client, peer mode server, our poll intvl 1024, peer poll intvl 1024
root delay 0.00 msec, root disp 10019.42, reach 377, sync dist 10045.227

the bug 

An IOS system may be unable to synchronize to an NTP server despite being able to transmit to and receive packets from the server. This may be seen with a Windows system running the w32time service. 'show ntp associations detail" will show that the server is flagged as "insane, invalid". The "root dispersion" value will be seen as being in excess of 1000 ms, which will cause the IOS NTP implementation to reject the association.

Workaround: instead of running the w32time service on the Windows system, use NTP 4.x - see http://www.eecis.udel.edu/~mills/ntp/html/hints/winnt.html

MHM

[Richard Burts]

I think MHM is probably correct that there is an issue about the Cisco learning NTP from a Windows server. I looked at the debug output:

009224: .Dec 8 15:33:34.622: NTP: xmit packet to 172.16.4.5:
009225: .Dec 8 15:33:34.622: leap 3, mode 3, version 3, stratum 0, ppoll 1024
009226: .Dec 8 15:33:34.622: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)
009227: .Dec 8 15:33:34.622: ref 00000000.00000000 (05:30:00.000 IST Mon Jan 1 1900)
009228: .Dec 8 15:33:34.622: org E91DB1D5.5471E372 (20:46:37.329 IST Fri Dec 8 2023)
009229: .Dec 8 15:33:34.622: rec E91DB1CE.A0D41973 (20:46:30.628 IST Fri Dec 8 2023)
009230: .Dec 8 15:33:34.622: xmt E91DB5CE.9F78127A (21:03:34.622 IST Fri Dec 8 2023)
009231: .Dec 8 15:33:34.622: NTP: rcv packet from 172.16.4.5 to 172.16.5.151 on Vlan164:
009232: .Dec 8 15:33:34.622: leap 0, mode 4, version 3, stratum 1, ppoll 1024
009233: .Dec 8 15:33:34.622: rtdel 0000 (0.000), rtdsp A172D (10090.530), refid 4C4F434C (76.79.67.76)
009234: .Dec 8 15:33:34.622: ref E91D9746.B300317E (18:53:18.699 IST Fri Dec 8 2023)
009235: .Dec 8 15:33:34.622: org E91DB5CE.9F78127A (21:03:34.622 IST Fri Dec 8 2023)
009236: .Dec 8 15:33:34.622: rec E91DB5D5.57186A5A (21:03:41.340 IST Fri Dec 8 2023)
009237: .Dec 8 15:33:34.622: xmt E91DB5D5.5718E325 (21:03:41.340 IST Fri Dec 8 2023)
009238: .Dec 8 15:33:34.622: inp E91DB5CE.A00993A0 (21:03:34.625 IST Fri Dec 8 2023)
009239: .Dec 8 15:33:34.622: NTP: nlist 0, allow 0, found 0, low 0.000000, high 0.000000
009240: .Dec 8 15:33:34.622: NTP: no select intersection
009241: .Dec 8 15:33:34.622: NTP: no select intersection

I think that what we are seeing is that the Cisco sends an ntp packet to the server, the server then sends an ntp packet to Cisco. I believe that "no select intersection" is an indication that there is some type of mismatch.

[MHM Cisco World]

hope next time two digit LOL...
B.regards 
MHM

[JforJignesh]

So, do you think Switch firmware/OS need to upgrade to get rid of this issue?

Or, is there any other way I can come out of this problem?

[M02@rt37]

Ok @JforJignesh 

Thanks for that test.

On your Windows 2022 Server, NTP server/service is alive/aware ? 

Windows Firewall don't block udp_123 segment ?

https://computingforgeeks.com/how-to-configure-ntp-server-in-windows-server/

[JforJignesh]

Yes Windows Server 2022 (Domain Controller) is configured as NTP server and other Windows Server 2022 domain node which are NTP clients are sucessfully synchronized with NTP server which is Windows Server 2022 (Domain Controller).