[189296] in North American Network Operators' Group
Re: Cost-effectivenesss of highly-accurate clocks for NTP
daemon@ATHENA.MIT.EDU (Bruce Simpson)
Sun May 15 03:21:16 2016
X-Original-To: nanog@nanog.org
To: nanog@nanog.org
From: Bruce Simpson <bms@fastmail.net>
Date: Sun, 15 May 2016 08:21:05 +0100
In-Reply-To: <20160513193927.BCB8F13A098B@snark.thyrsus.com>
Errors-To: nanog-bounces@nanog.org
On 13/05/16 20:39, Eric S. Raymond wrote:
> In 2012, nearly three years before being recruited for NTPsec, I
> solved this problem as part of my work on GPSD. The key to this
> solution is an obscure feature of USB, and a one-wire
> patch to the bog-standard design for generic USB that exploits
> it. Technical details on request, but what it comes down to is
> that with this one weird trick(!) you can mass-produce primary time
> sources with a jitter bounded by the USB polling interval for
> about $20 a pop.
>
> The USB 1 polling interval is 1ms.
What about USB 3.1 (assuming the device is not intended to be backwards
compatible with the polling model) ? I should point out Intel intend to
retire EHCI/UHCI and implement only xHCI.
