Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

NTP Configuration as of 1 Jan 2010

For some reason the clocks on some of my switches will not update via NTP.  The NTP configuration has not changed, nor has the time source.

This output is from a switch that will not sync.  There is no firewall between the switch and the time server.

#sh ver

Cisco IOS Software, C3550 Software (C3550-IPSERVICESK9-M), Version 12.2(44)SE6, RELEASE SOFTWARE (fc1)

#sh clock detail
*18:04:07.411 CST Sun Feb 28 1993
Time source is NTP
Summer time starts 02:00:00 CST Sun Mar 14 1993
Summer time ends 02:00:00 CDT Sun Nov 7 1993

#sh run | begin ntp
ntp server

#sh run | begin clock
clock timezone CST -6

#sh ntp associations detail configured, insane, invalid, unsynced, stratum 16
ref ID, time 00000000.00000000 (18:00:00.000 CST Thu Dec 31 1899)
our mode client, peer mode unspec, our poll intvl 64, peer poll intvl 64
root delay 0.00 msec, root disp 0.00, reach 0, sync dist 0.000
delay 0.00 msec, offset 0.0000 msec, dispersion 16000.00
precision 2**5, version 3
org time CEF07314.B2A686E7 (08:49:56.697 CST Thu Jan 7 2010)
rcv time AF3BD1FF.798AFE6A (18:06:23.474 CST Sun Feb 28 1993)
xmt time AF3BD1FF.78DA09D2 (18:06:23.472 CST Sun Feb 28 1993)
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


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


Re: NTP Configuration as of 1 Jan 2010


Check out the below points between the switch and NTP server

1. Issue the command show ntp status on the NTP server to make sure that NTP server
   has synched its clock. If it is not synched, verify the NTP server's configuration.
   If the NTP server is not synchronized itself try to disable and re-enable the
   NTP configuration on the server.
2. If authentication is configured between the server and client, make sure that
   authentication-key number and md5 key values are matching. Also, verify that
   key number is included in the ntp server {server_address} of the client configuration.

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.

The 'reach' counter shows a value of 0 for the following configured NTP
server IP address(es):

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

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

Hope this helps out your query !!