[ntp:questions] ntpdate.c unsafe buffer write

David L. Mills mills at udel.edu
Thu Feb 14 04:26:09 UTC 2008


The natural behavior of a bunch of oscillators near the same frequency 
is to become one giant phase-locked oscillator. Adding a bit of random 
fuzz at each poll turns each oscillator into a mini random-walk which 
breaks up that tendency. The fuzz is not a lot, like 10 percent.


Maarten Wiltink wrote:
> "David L. Mills" <mills at udel.edu> wrote in message
> news:fots64$2g7$1 at scrotar.nss.udel.edu...
>>>>No, there is no random delay at startup. Each association starts one
>>>>second after the previous one. The random backoff occurs only after
>>>>a step.
>>>Is there also a random backoff after an increase of the polling
>>No. However, there is a small dither of a few percent at all poll
>>intervals to resist self-synchronization.
> Wouldn't that be a nice feature to add? If it's currently polling a
> server on, say second 100 (reckoned externally) of 256, to go to
> either 100 _or 356_ of 512.
> I understand that there are already some random waits in the client
> code and Internet servers are well protected by random noise. But
> for large numbers of clients in a uniform environment that were all
> started at about the same time, is there any way they tend to
> naturally disperse across the final 1024s polling interval?
> Groetjes,
> Maarten Wiltink

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