NTP Synchronization

Unanswered Question
Feb 21st, 2010

Hi,

I have configured a NTP server with my Core Switch, It was running after configured, suddenly I have observed that, its not getting synchronizing.

Please help me to get this solve.

Find some command output below:

ST-DC-SW-Core-6509-1#sh ntp status
Clock is synchronized, stratum 8, reference is 127.127.7.1
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**18
reference time is CF2BCEB5.151455CA (18:24:37.082 BHC Sun Feb 21 2010)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.02 msec, peer dispersion is 0.02 msec

ST-DC-SW-Core-6509-1#sh run | i ntp
ntp clock-period 17179864
ntp source Vlan90
ntp master
ntp update-calendar
ntp server 172.18.136.2

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Ganesh Hariharan Sun, 02/21/2010 - 23:30

Hi,

I have configured a NTP server with my Core Switch, It was running after configured, suddenly I have observed that, its not getting synchronizing.

Please help me to get this solve.

Find some command output below:

ST-DC-SW-Core-6509-1#sh ntp status
Clock is synchronized, stratum 8, reference is 127.127.7.1
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**18
reference time is CF2BCEB5.151455CA (18:24:37.082 BHC Sun Feb 21 2010)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.02 msec, peer dispersion is 0.02 msec

ST-DC-SW-Core-6509-1#sh run | i ntp
ntp clock-period 17179864
ntp source Vlan90
ntp master
ntp update-calendar
ntp server 172.18.136.2

Hi,

The output says your clock is synchronized with startum vlaue 8,can you paste your output for show ntp association output also.

Ganesh.H

goutam_04 Mon, 02/22/2010 - 06:10

Hi,

Its synchronized with local clock 127.127.7.1

but actual NTP server IP is 172.18.136.2.

ST-DC-SW-Core-6509-1#sh ntp associations

      address         ref clock     st  when  poll reach  delay  offset    disp
*~127.127.7.1      127.127.7.1       7    58    64  377     0.0    0.00     0.0
~172.18.136.2     0.0.0.0          16     -  1024    0     0.0    0.00  16000.
* master (synced), # master (unsynced), + selected, - candidate, ~ configured
ST-DC-SW-Core-6509-1#

I need to synchronized with 172.18.136.2 (NTP Server)

Ganesh Hariharan Mon, 02/22/2010 - 06:34

Hi,

Its synchronized with local clock 127.127.7.1

but actual NTP server IP is 172.18.136.2.

ST-DC-SW-Core-6509-1#sh ntp associations

      address         ref clock     st  when  poll reach  delay  offset    disp
*~127.127.7.1      127.127.7.1       7    58    64  377     0.0    0.00     0.0
~172.18.136.2     0.0.0.0          16     -  1024    0     0.0    0.00  16000.
* master (synced), # master (unsynced), + selected, - candidate, ~ configured
ST-DC-SW-Core-6509-1#

I need to synchronized with 172.18.136.2 (NTP Server)

Hi,

The 'reach' counter shows a value of 0 for the following configured NTP server IP address(es):  172.18.136.2
This means that the router did not receive at least the last eight NTP packets it expects to receive. Usually this counter shows a value of "377" which means that device has received at least the last eight NTP packets.

Check out the following things:-

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

2.Enable the debug ntp packet command to make sure that NTP packets are received from the server(s).

3.Make sure that NTP packets are not blocked by the access-list statement.

4.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.

Hope to Help !!

If helpful do rate the post

Ganesh.H

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