[ntp:questions] Re: status of multicast

David L. Mills mills at udel.edu
Mon Nov 29 14:30:06 UTC 2004


The initial clock offset is computed with unicast and should not involve 
a step adjustment, unless the initial system clock is off by over 128 
ms. Once the broadcast offset has been determined by this means, 
subsequency offsets should not exceed 128 ms.


David Woolley wrote:
> In article <coe145$n9h$1 at dewey.udel.edu>, David L. Mills <mills at udel.edu> wrote:
>>use a unicast path, as that's how it can determine the broadcast delay, 
>>in your case probably 270 ms. I don't know why it volleys with the 
> As described, the roundtrip delay estimate will be badly flawed as
> at least the output leg from the client is terrestial (if the whole
> exchange is terrestial, the point to point measurement will disagree
> by more than the step threshold, which, I suppose, might cause the
> server to be rejected - even if just the one leg is terrestial, I think
> the error will exceed 128ms).

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