[ntp:questions] tinkering with minpoll and maxpoll

David Mills mills at udel.edu
Sat Nov 7 16:22:29 UTC 2009


The absolute minimum poll exponent 3 (8 s) is required by stability 
considerations and the adjustment interval of 1 s. The absolute maximum 
poll exponent 17 (36 h) is an arbitrary choice based on the wander 
characteristics of commodity computer clock oscillators. The default 
minimum of 6 (64 s) and default maximum of 10 (1024 s) were set thirty 
years ago by mindless conjecture, but have proven good choices under 
typical LAN and WAN conditions. When you hook up your cesium oscillator, 
you may need to reconsider these choices.


Aneeq Mahmood wrote:

>HI all,
>Can someone shed some light on the default values of MINPOLL , MINDPOLL ,
>MAXPOLL etc etc in ntp.h file.
>I can not understand the logic for choosing these particular numbers. If
>there is any then please share it with me. Also what ramifications i can
>face if i decide to change these values as far as synchronization of my
>network is concerned. Some comments on that will be appreciated.
>questions mailing list
>questions at lists.ntp.org

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