[ntp:questions] ntpd: time reset problem

David Lord snews at lordynet.org
Mon Sep 14 17:21:35 UTC 2009


Steve Kostecke wrote:
> On 2009-09-14, David Lord <snews at lordynet.org> wrote:
> 
>> Frank Elsner wrote:
>>
>> OT you also have rather a lot of sources specified and if just for a
>> single box it seems a bit excessive and could be trimmed to four or
>> five (I'd also guess some of those eight get same refid).
> 
> Red Herring.

No, you missed the OT.

> 
>> I've just been trying mobile broadband on a high latency connection
>> and it was too much for ntpd at 1-2 sec average and 150ms best to 10
>> sec/timeout at worst :-)
>>
>> Then this weekend after reconfigured to use "burst" in server lines
> 
> "burst" is an 8x multiplier that is applied to each poll.
> 
> The use of "burst" against other peoples' time servers is generally
> considered to be abuse unless you have received permission to do so.

Can you then suggest how it's at all possible for ntpd to be
of any use on a mobile connection with such high latency?

Minpoll was also set to 8 which doesn't exactly compensate
but does mitigate to some extent.

Probably from that quick test where time was set to within
20 ms rather than still 2 sec out after 30 min the poll
interval could have been reduced further, however I'm pretty
sure using other than "burst" would not have synced the time
before system had to be shutdown.

I just need to get something working that's significantly
better than wristwatch time.

Anyway "burst" works and I now give myself permission to use
"burst" to set time from my own ntp servers which is as good
a compromise as any :-)

They are on public facing servers but I probably don't have
sufficient usage allowance to offer them as pool servers.


David




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