what does mean by ntp clock-period 17180442

Posted on 2008-02-11
Medium Priority
Last Modified: 2013-12-12
I configured ntp interface and server ip. It's working, but it added this statement into cisco config "ntp clock-period 17180442".  It's recommended that it should not be configured manually. I would like to know what does it mean? What is the significance of this no? what's the freqency of time update?

Question by:msaalim
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Assisted Solution

batry_boy earned 600 total points
ID: 20869364
From Cisco's website:

Caution Do not enter this command; it is documented for informational purposes only. The system automatically generates this command as Network Time Protocol (NTP) determines the clock error and compensates.


As NTP compensates for the error in the software clock, it keeps track of the correction factor for this error. When the value for the clock period needs to be adjusted, the system automatically enters the correct value into the running configuration. To remove the automatically generated value for the clock period, use the no form of this command.

ntp clock-period value

no ntp [clock-period value]

Syntax Description
 Amount of time to add to the software clock for each clock hardware tick (this value is multiplied by 2-32).
LVL 44

Expert Comment

ID: 20871451
17180442 * 2^-32 = 0.0040001333691179752349853515625

In case you wondered. :-)

Author Comment

ID: 20885915
How do we know what's the update interval for time update? Can it be configured to desired interval? If I configure more than one ntp server, does the switch use 2nd ntp server only in case first server is not available. Does it use its own preference or configured sequence order for time update?

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Accepted Solution

Darr247 earned 900 total points
ID: 20886280
Use an atomic-clock-synced NTP server such as time.windows.com:123 or otc2.psu.edu:123 to sync the clock and the Cisco keeps track of the adjustments, interpolating the clock-period value... the more samples over a long period of time, the more accurate it should become. i.e. except for leap seconds added (doesn't happen very often), and assuming a good power supply, it should eventually not need external correction.

Unless you decide to use the 'no ntp [clock-period value]' command.

Author Comment

ID: 21060426

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