[ntp:questions] ntp server specs

unruh unruh at wormhole.physics.ubc.ca
Thu Apr 21 18:17:52 UTC 2011

On 2011-04-21, Mike S <mikes at flatsurface.com> wrote:
> At 08:51 PM 4/20/2011, unruh wrote...
>>More like 10-100us.
> Not on anything with more than a single hop across 1000base?, 
> especially when you consider irq/processing jitter at both ends. If an 
> NTP UDP packet is behind a single max length Ethernet frame on 1G, it's 
> delayed 12 us. Go across a 10 Mb MAN, and you've got over 1 ms of 
> jitter, even with NTP given high priority QoS, which is unlikely.

jitter? Anyway, much of that is symmetric and thus irrelevant. Anyway I
was reporting on experiments I did, not theory.

> (_wormhole_.physics.ubc.ca? Your net admins don't know how to filter 
> spam?) 


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