NTP problem

t-yamashita · ‎02-03-2010

Hi all,

I have a problem regarding NTP sync.

For some reason the clocks on my Cat2960 will not update via NTP(C1812).

There is no firewall and authenticaton between the Cat2960 and the NTP(C1812) .

Following out put is from a Cat2960 that will not sync.

#show ver

Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 12.2(44)SE6, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Mon 09-Mar-09 18:10 by gereddy
Image text-base: 0x00003000, data-base: 0x01100000

#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 (00:00:00.000 UTC 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

#ping 192.168.1.254 <---- NTP(C1812)

!!!!!!

Please take a look at the .pdf for detail.

Best Regards

Tomoyuki

Ganesh Hariharan · ‎02-03-2010

Hi all,

I have a problem regarding NTP sync.

For some reason the clocks on my Cat2960 will not update via NTP(C1812).

There is no firewall and authenticaton between the Cat2960 and the NTP(C1812) .

Following out put is from a Cat2960 that will not sync.

#show ver

Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 12.2(44)SE6, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Mon 09-Mar-09 18:10 by gereddy
Image text-base: 0x00003000, data-base: 0x01100000

#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 (00:00:00.000 UTC 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

#ping 192.168.1.254 <---- NTP(C1812)

!!!!!!

Please take a look at the .pdf for detail.

Best Regards

Tomoyuki

Hi Tomoyuki,

As the error says NTP clock status of 'unsynced' with the NTP server(s):

Try to do the following steps to overcome the issue:-

1. Make sure that configured NTP server(s) is reachable by pinging the server IP address(es).

2. Issue the command show ntp status on the server(s) to make sure that NTP serverhas synched itself. If it is not synched, verify the server NTP configuration.The show ntp status of the server should display a status of 'sync' beforeclients can sync their clock with the server.
3. Verify that the 'stratum' value configured on the server is valid for your setup.configure a high stratum number to ensure that this router does not override the clock on another system with a lower stratum number. The lower stratum number indicates a more reliable clock.
5. Make sure that NTP packets are not blocked by the access-list statement.
6. Paste the show ntp associations if not able to sync with ntp server.

Hope to help

Ganesh.H

t-yamashita · ‎02-03-2010

Hi Ganesh.H,

Thanks for your quick response.

I think I've already cofirmed all steps.

1. NTP server is reachable by pinging the server.

2. NTP server has synched the server as following.

NTP_Server#sh ntp a

      address         ref clock     st when poll reach delay offset    disp
~127.127.7.1      127.127.7.1       7     9    64 377     0.0    0.00     0.0
*~210.145.255.76   202.234.233.105   3   445 1024 377     8.6    0.23     3.2      <<< server in the ISP
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

3. 'stratum' value configured on the server is valid as following.

NTP_Server#sh ntp status
Clock is synchronized, stratum 4, reference is 210.145.255.76
nominal freq is 250.0000 Hz, actual freq is 249.9950 Hz, precision is 2**18
reference time is CF03DC3E.243ED1AF (17:11:42.141 JST Fri Jan 22 2010)
clock offset is 0.2281 msec, root delay is 28.00 msec
root dispersion is 52.98 msec, peer dispersion is 3.17 msec

4.There are not any ACLs between Switch and NTP server.

By the way we CAN'T repro this problem in our lab.

(as the same product, ios, and nearly conposition)

Any other idea?

Best Regards,

Tomoyuki

Ganesh Hariharan · ‎02-03-2010

Hi Ganesh.H,

Thanks for your quick response.

I think I've already cofirmed all steps.

1. NTP server is reachable by pinging the server.

2. NTP server has synched the server as following.

NTP_Server#sh ntp a

      address         ref clock     st when poll reach delay offset    disp
~127.127.7.1      127.127.7.1       7     9    64 377     0.0    0.00     0.0
*~210.145.255.76   202.234.233.105   3   445 1024 377     8.6    0.23     3.2      <<< server in the ISP
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

3. 'stratum' value configured on the server is valid as following.

NTP_Server#sh ntp status
Clock is synchronized, stratum 4, reference is 210.145.255.76
nominal freq is 250.0000 Hz, actual freq is 249.9950 Hz, precision is 2**18
reference time is CF03DC3E.243ED1AF (17:11:42.141 JST Fri Jan 22 2010)
clock offset is 0.2281 msec, root delay is 28.00 msec
root dispersion is 52.98 msec, peer dispersion is 3.17 msec

4.There are not any ACLs between Switch and NTP server.

By the way we CAN'T repro this problem in our lab.

(as the same product, ios, and nearly conposition)

Any other idea?

Best Regards,

Tomoyuki

Tomoyuki,

Can you share the output of cat 2960 show ntp association

Ganesh.H

t-yamashita · ‎02-04-2010

Ganesh.H,

I don't have the log now.

But I'll go to the user network environment and I gonna get and post the log tommorow.

For your information,

following massage is resulted when I put Wireshard on the line between switch and NTP servers,

I think that the switch was sending NTP packet, but NTP server couldn't reply for any reason.

No.     Time                       Source                Destination           Size Protocol Info
   2111 2010-02-02 11:01:32.051439 192.168.1.249         192.168.1.254         90    NTP      NTP
   2149 2010-02-02 11:01:33.046922 192.168.1.249         192.168.1.254         90    NTP      NTP
   2174 2010-02-02 11:01:34.053549 192.168.1.249         192.168.1.254         90    NTP      NTP
   2199 2010-02-02 11:01:35.051831 192.168.1.249         192.168.1.254         90    NTP      NTP
   2235 2010-02-02 11:01:36.050142 192.168.1.249         192.168.1.254         90    NTP      NTP
   2266 2010-02-02 11:01:37.048496 192.168.1.249         192.168.1.254         90    NTP      NTP
   2302 2010-02-02 11:01:38.049292 192.168.1.249         192.168.1.254         90    NTP      NTP
   3313 2010-02-02 11:01:47.048123 192.168.1.249         192.168.1.254         90    NTP      NTP

Thanks.

Tomoyuki