[ntp:questions] strange behaviour of ntp peerstats entries.

Brian Utterback brian.utterback at sun.com
Mon Jan 28 15:22:36 UTC 2008


Unruh wrote:

> I am also a little bit surprized that it is the delay that is used and not
> the total roundtrip time. As I seem to read it, the delay is (t4-t3+t2-t1)
> ie, it does not take into account the delay within the far machinei (eg
> t4-t1), but
> only propagation delay. I would expect that the former might even be more
> important than the latter, but that is a pure guess-- ie no measurements on
> even one system to back it up. 
> Now it may be that on that rocky road to Manila, the propagation delay is
> by far the most important, but on a moderm lan, especially with a low
> propagation delay of hundreds of usec rather then 100s of msec, I wonder. 
> 

The calculation of the offset is not affected at all by the time between
taking the two timestamps on the remote machine. In fact, on symmetric
peers, this time could be in the thousands of seconds or more.

Brian Utterback




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