Time and Timing Servers

Fri Jul 12 05:10:57 UTC 2019

Subject: Re: Time and Timing Servers Date: Thu, Jul 11, 2019 at 10:23:41AM -0500 Quoting Mike Hammett (nanog at ics-il.net):
> I'll look into Meinberg. 

Meinberg are nice people with good hardware. They can do 2048KHz from
GPS and other timing signals, for instance. Then again, some router
vendors do that in boxes you need anyway. As long as the controlling
clock is PTP.

> I recent thread mentioned high-sensitivity receivers often allow GPS to work inside. Obviously "inside" has a lot of definitions. 

Indeed. Colo buildings rarely are on the forgiving side of "inside".
In Sweden, most older central offices are built to some degree of bomb
proofness (certainly not safe from direct hit) , with some 10mm of steel
in shutters for all windows, etc. GPS fares not well there. 

> I will need this facility for the TDM timing signals. It's a central office, not a datacenter. 

Then you're concerned with frequency and phase to ITU-T G.812, I
suspect. Unless this is your "central central" office, in which case
you need G.811.

> I don't know that Internet-based NTP would be accurate enough for the timing signals that I need. Maybe, maybe not. 

The current trend in today's large frequency/phase consumers, ie. mobile,
is to run PTP over backhaul.  Well behaved NTP _could_ make it, I suspect,
given a good enough clock in the facility, but PTP will definitely work,
assuming you have transmission and hardware capable of doing it. 

"Capable" here, means dark fibre or WDM is required together with
routers and switches that can act as boundaries in PTP sense. If you
rent MPLS or are using plain Internet infrastructure, it becomes a lot
more complicated.

There are frequency/phase transmission solutions (mostly broadcast
related) that easily can transfer your central central cæsium clock
frequency to another site using reasonable-quality IP transport, but
those are neither cheap nor fire-and-forget.

-- 
Måns Nilsson     primary/secondary/besserwisser/machina
MN-1334-RIPE           SA0XLR            +46 705 989668
I'm gliding over a NUCLEAR WASTE DUMP near ATLANTA, Georgia!!
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