[ntp:questions] ntp won't lock

Rob nomail at example.com
Thu Dec 3 09:15:04 UTC 2009


I have a strange problem with NTP in a Cisco 877.

On a couple of locations we have Cisco routers and NTP works "ok"
on them (of course, better NTP software exists).  But this one router
won't remain locked.

When I remove the NTP server and add it again, and then look with
"sh ntp as", it looks like it is synced but the offset is ever
increasing.  After a couple of minutes, the server suddenly is indicated
as unreachable and the offset is smaller again.  Sync seems lost but
the time is about right.

output of a couple of "sh ntp as" commands every 80 seconds or so:

      address         ref clock     st  when  poll reach  delay  offset    disp
*~194.109.22.18    193.67.79.202     2    11    64  377    20.8   49.29   141.1
*~194.109.22.18    193.67.79.202     2    16    64  377    20.5  1084.1   498.6
*~194.109.22.18    193.67.79.202     2    45    64  377    15.4  1877.6   453.2
*~194.109.22.18    193.67.79.202     2     1    64  377    22.2  2942.1   596.1
*~194.109.22.18    193.67.79.202     2    54    64  377    22.2  2942.1   596.1
*~194.109.22.18    193.67.79.202     2    62    64  377    22.2  2942.1   596.1
*~194.109.22.18    193.67.79.202     2     2    64  377    21.2  3207.2   553.8
 ~194.109.22.18    193.79.237.14     2    30    64    0    20.7  265.03  16000.

Other routers sync OK from this same server....

Config is like this:
ntp clock-period 17179870
ntp server 194.109.22.18 source Dialer10


What could be wrong here?
The clock-period has been inserted by the router itself, as normal.




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