[ntp:questions] Compensating for asymmetric delay on a per-peer/server basis?

William Unruh unruh at invalid.ca
Thu Sep 11 18:58:38 UTC 2014

On 2014-09-11, mike cook <michael.cook at sfr.fr> wrote:
> Le 11 sept. 2014 ? 18:48, Rob a ?crit :
>> Paul <tik-tok at bodosom.net> wrote:
>>> As an aside has anyone tried shaping traffic to make the
>>> upstream/downstream latencies similar?  It would seem more efficient
>>> to apply network solutions to network problems if possible.
>> That does not work.  The asymmetry is not caused by traffic but by
>> modem parameters.
>   Did I miss something? The OP did not offer any evidence that there was path asymmetry, just that there was an unexplained offset between two GPS sync'd servers. It is often not possible to identify the origin of such an offset, but it would help if the suggested feature was implemented to take care of these corner cases. I saw that Dr Mills was in agreement back in 2005 but that the implementation is complex. If anyone wants a subject for an MSc project, this could be it.

No idea why a fudge parameter would be complicated. If you wanted to use
ntpd itself to figure out the assymmetry, that could well be
complicated. But if it is a fixed offset, I cannot see how that would be
complicated and it ihas already been implimented in the refclock case.

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