[ntp:questions] 1Gb/s network issues - was: Re: OT: GPS18x LVC failure
David J Taylor
david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid
Tue Oct 13 07:25:33 UTC 2009
"Kasper Pedersen" <> wrote in message
news:4ad360ef$0$36567$edfadb0f at dtext01.news.tele.dk...
[]
> I built a device that spits out priority tagged ethernet frames with
> <200ns error to UTC, and did a number of tests with different networks
> and nics, the result of which is in a table here:
>
> http://n1.taur.dk/etherpps/
>
> On switches that understand priority tagging it makes a world of
> difference. On the corporate network where I had 14us unaccounted
> latency and 18us jitter with the packet prioritized above all other
> traffic, when the prioritization was disabled I got another 200us jitter
> at peak load time (users and iscsi traffic sharing the same path).
>
> I suppose there's a way to make the kernel priority tag outbound ntp
> packets, but I did not find it.
>
> /Kasper Pedersen
Many thanks for posting that, Kasper, most interesting!
David
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