http://www.brillianttelecom.com/ is another timing solutions provider -henry ________________________________ From: Matthew Huff <mhuff@ox.com> To: Kyle Bader <kyle.bader@gmail.com>; "nanog@nanog.org" <nanog@nanog.org> Sent: Thu, March 25, 2010 5:27:09 AM Subject: RE: NTP clock source http://www.symmetricom.com/ We have two of their S200 syncservers. Works great. ---- Matthew Huff       | One Manhattanville Rd OTA Management LLC | Purchase, NY 10577 http://www.ox.com  | Phone: 914-460-4039 aim: matthewbhuff  | Fax:   914-460-4139

-----Original Message----- From: Kyle Bader [mailto:kyle.bader@gmail.com] Sent: Thursday, March 25, 2010 8:52 AM To: nanog@nanog.org Subject: NTP clock source

Can anyone recommend a solid clock souce (stratum 0) that's not overly expensive? The only stuff I've found so far is ESE, can anyone recommend them or conversely has anyone had any problems with their hardware?

--

Kyle

On 3/25/2010 7:03 AM, Dave Hart wrote:

On Thu, Mar 25, 2010 at 12:51 UTC, Kyle Bader <kyle.bader@gmail.com> wrote:

...

Can anyone recommend a solid clock souce (stratum 0) that's not overly expensive?

All the options I'm aware of have no prices posted, sadly. For me, that means "forget it, you don't want to spend that much", but then I'm not spending other people's money :)

In addition to Symmetricom and EndRun Technologies, Meinberg has a solid reputation in this space:

http://www.meinberg.de/english/products/#network_sync

I'm biased toward Meinberg because several of their staff contribute their skills to the development and maintenance of the ntp.org reference implementation. They have also been generous donating hardware over the years to ntp.org and pool.ntp.org, and their Windows NTP binaries and GUI installer are widely used.

I totally agree! Meinberg's M300's rock solid and JTime is really easy to deal with as are its distributor's.

The cheapest solution involves the Garmin GPS 18x LVC receiver and a soldering iron. Unlike the USB and "PC" (232) versions of the GPS 18x, the LVC version supplies a pulse-per-second signal which makes it suitable for sub-millisecond NTP sync. The supplied connector has to be cut off, a DB-9 serial hood wired in its place, and either a USB cable or other 5V power supply needs to be attached. Or you can do as I did and pay for the completed GPS 18x LVC with DB-9 and USB connectors from a third party. $105 from:

True - you can build very accurate timekeeping service practices, but ALL GPS-L1 based systems have one flaw - the provability of the time data is squat. The evidence-model from a passive L1 system no matter how accurate it is - is zero... zip... it has as much legal impact with a competent lawyer on the other side, as you looking at mickey on your wrist and setting the ToD by hand daily. This is becoming more and more important in the world of commercial computing and something that timekeeping will have to morph towards to insure its not unseated...

You also need a junkbox PC with real serial ports (not via a USB adapter), or the capacity on an existing server. The GPS 18x cable is either 3m or 5m long, if your PC is not close enough to a southern-exposed window or to roof access for the 18x to lock, you may also need a RS-232 extension cable and USB power supply. Unlike timing-focused GPSes, the 18x needs 3 or more birds in view to provide a PPS signal.

Good luck, Dave Hart

On 3/25/2010 10:40 AM, Dan Shoop wrote:

On Mar 25, 2010, at 8:51 AM, Kyle Bader wrote:

...

Can anyone recommend a solid clock source (stratum 0) that's not overly expensive? The only stuff I've found so far is ESE, can anyone recommend them or conversely has anyone had any problems with their hardware?

Why would you want a S-0 Clock??? You are not a time-space lab, and so you would want something like a stratum-2 time source which comes from a provable provider. There are laws by the way on what are official and non-official sources of time. In the US for instance these are 15 USC 271 and 272, and the right to deploy the time is codified in 15 USC 260 so which source of time is used is important. By the way - if this is a commercial use, try applying the same set of controls to the time provider you are forced to apply to the rest of the outsourcing service providers you rely on...

...

--

Kyle

We have several symmetricom time servers that we use in several location and I'd recommend them very highly. '

Depends on whether you are trying to generate evidence of something or not. If you need to be able to prove the time data is correct, then you will need a process to do that, a process which most all of the time server systems to date choke on pretty badly. Since the GPS-L1 system without SAASM encryption was formally banned by the US Military for use in their systems by an order of the Joint Chiefs of Staff in 1998, its pretty clear that relying on GPS-L1 for anything requiring a sense of digital trust is out. NTP Peer Stats files have virtually no way of associating content to events meaning that the time-tokens which are passed around are lost in the wind, meaning that there is no enduring evidence generated by NTP. The NTP loopstat and peerstat files have just enough info to be dangerous and not enough to prove anything to the existing rules of evidence, so the real issue is whether you have to prove something as a response to a regulatory requirements or you just want to synchronize the systems in question for... Todd

-d

------------------------------------------------------------------------ Dan Shoop Computer Scientist shoop@iwiring.net

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