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Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com

Midwest-IX
http://www.midwest-ix.com

From: "James Harrison" <james@talkunafraid.co.uk>
To: nanog@nanog.org
Sent: Wednesday, May 1, 2019 5:27:38 PM
Subject: Re: NTP question

On 01/05/2019 20:29, Job Snijders wrote:
> The trick is to order a spot on the roof of the datacenter, have the
> facility staff place the antenna there, and run a cable to the NTP
> server in your rack.

Some DCs also offer GPS antenna feeds fed from a splitter, though it's
important to get the total cable length from the antenna to your
receiver so you can set your propagation delay offset accordingly. I've
also been in facilities that distribute IRIG and 10MHz references so you
can feed a reference directly, but that's fairly rare.

It's worth asking what your facilities can provide, in either case. Many
DCs don't want a dozen GPS antennae cluttering the roof up but are happy
to provide the service from one they look after (for a cost, of course).

If you have external facilities, of course, so long as you can run
PTP/1588 back from them, you can always host your clocks there and
distribute to 1588 masters in the DC.
--
Cheers,
James Harrison