[VoiceOps] NTP Question

Henning Westerholt hw at skalatan.de
Tue Feb 18 09:02:34 EST 2020 

(re-send because of blocking of the previous e-mail)

Hello,

my experience is mostly with German market - here you need to prove (when you have enough customer base) to the regulation authorities that your time source that is used for billing is accurate enough. During that time when I was working on such a project, the regulation authorities were satisfied with something in the hundreds of milliseconds/less than 0,5s drift in the platform towards the official time base. In the end the old PSTN technology probably did not provided more accuracy..

If I would look to a platform from an auditor point of view, I would focus more on process accuracy, monitoring and general operation procedures. Like - if there is a deviation in the time synchronisation, it is actually detected. Are there other events or sources where wrong billing could be generated, like a crash of a system etc..
These process issues can cause more billing problems than some delay due to an NTP on a virtual machine (if you take the extreme examples with 10-20s drift as mentioned earlier away) in my opinion.

Cheers,

Henning

-- 
Henning Westerholt - https://skalatan.de/blog/
Kamailio services - https://gilawa.com
 

-----Original Message-----
From: VoiceOps <voiceops-bounces at voiceops.org> On Behalf Of Alex Balashov
Sent: Tuesday, February 18, 2020 2:20 PM
To: voiceops at voiceops.org
Subject: Re: [VoiceOps] NTP Question

I'm still going to maintain that VMs are fine in our considerable experience, as long as the hypervisor environment isn't "out of the ordinary" and your applications of NTP aren't the kinds for which nothing less than the precision of a cesium clock will do. What does Metaswitch do with its system clock? Cut CDRs? 

-- Alex

On Tue, Feb 18, 2020 at 07:04:35AM -0600, Mike Hammett wrote:

> I would love to have my own stratum one in each Frontier CO we're in. Unfortunately, we don't have access to put GPS antennas on the buildings and the important buildings don't have windows and have us behind multiple layers of brick walls\concrete floors, so an indoor antenna isn't likely to work. 
> 
> 
> Clocks that accept their information via PTP from a location where we can put up a GPS antenna run into the thousands of dollars (though I am still waiting on quotes), thus aren't exactly reasonably priced. 
> 
> 
> 
> 
> To seemingly conclude the thread, 3 are required, 4 or 5 are recommended. VM NTP servers are to be avoided. 
> 
> 
> 
> 
> I'll roll with VMs for now while I develop a plan to have something there I can use the hardware directly (no VM). I'll swap out each VM for hardware when a reasonable course of action is available. 
> 
> 
> 
> 
> -----
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
> 
> 
> 
> Midwest Internet Exchange
> http://www.midwest-ix.com
> 
> 
> 
> ----- Original Message -----
> 
> From: "Peter Beckman" <beckman at angryox.com>
> To: "Tim Bray" <tim at kooky.org>
> Cc: voiceops at voiceops.org
> Sent: Monday, February 17, 2020 10:02:46 PM
> Subject: Re: [VoiceOps] NTP Question
> 
> Ooooh I like that one! 
> 
> The thread got a little confusing --
> 
> Are we talking about using NTP as a client on VMs? 
> 
> Or using VMs to run NTP servers? 
> 
> If as a server: 
> Hell NAH! Don't do it. Like everyone said, the clock available to the 
> OS isn't reliable, you don't want its drift to affect other machine's 
> clocks.
> 
> If as a client: 
> Hell YAH! VM clocks are unreliable. Heck, we had a dedicated server 
> that had a 14 second a day drift! We used the heck out of NTP to keep 
> that sucker from losing time.
> 
> Sort of related: I really love OVH as a hosting provider, but they 
> offer one time source, and it is in Beauharnois, Canada, even if you 
> use their Oregon US Datacenter. These NTP devices are so inexpensive 
> to cover a whole datacenter, why are we introducing network latency?!?
> 
> I am of the opinion that each physical datacenter should provide its 
> own Stratum 1 NTP source.
> 
> Beckman
> 
> On Tue, 18 Feb 2020, Tim Bray via VoiceOps wrote: 
> 
> > On 17/02/2020 21:52, Mike Hammett wrote: 
> >> How many NTP servers do you guys run? 
> >> I just spun up two NTP servers in different locations on this network. 
> >> Metaswitch just asked me for at least four (preferably five, or even more). 
> >> Right now, the ones I have are just referencing the US pool. 
> >> Eventually, they'll reference on-net GPS-backed devices.
> > 
> > 
> > https://store.uputronics.com/index.php?route=product/product&path=60
> > _70&product_id=92
> > 
> > 
> > LeoNTP server. If you want to run your own. 
> > 
> > 
> > 
> > 
> > 
> > --
> > Tim Bray
> > Huddersfield, GB
> > tim at kooky.org
> > +44 7966479015
> > 
> > 
> 
> ----------------------------------------------------------------------
> -----
> Peter Beckman Internet Guy
> beckman at angryox.com http://www.angryox.com/
> ----------------------------------------------------------------------
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--
Alex Balashov | Principal | Evariste Systems LLC

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