On 13.03.2014 13:00, questions-requ...@lists.ntp.org digested: > From: Olivier Drouin <ol.dro...@gmail.com> > > For exemple, Endrun Technologies sells the Sonoma N12 which seems to > allow time synchronization against CDMA signal without the need for > a carrier subscriptions.
(This thing supposedly answers more requests per second than I've set up NTP clients in my entire life: http://www.endruntechnologies.com/ntp-server.htm - do you have thousands of *local* clients to serve and/or a Gigabit uplink to bring that throughput to *remote* ones?) > If not, do I have other options beside a GPS antenna with a sky view? Horror story: I once set up a customer's housing rack, right next to a window, with a DCF77 receiver cable-tied onto its top. (That was less than 50km from the DCF77 antenna array supposedly serving the whole of Central Europe, mind.) Half a year into operation, reception plain stopped and never came back, with no change in nearby racks apparent to the naked eye. If quietly watching your N12 turn into a $5,000 rack weight is not an option, then IMHO neither is an indoor antenna that the building administration doesn't officially know about and support. (I've also seen server rooms where you have to actually stand next to a specific window a dozen meters from the nearest rack to get any GSM reception, so potential reception problems are definitely not limited to DCF77 and/or GPS.) You specifically asked about syncs where the ultimate source is GPS. There are lots of forms of time syncing built into building automation systems (ISDN, single-wire, fire alarms, ...), as well as into WAN connections you might have in your very rack, but there's likely some DIY involved and you very likely will not get the same precision ... (Personal opinion: I just don't get why there apparently are so many hosting/housing/colo providers where you *cannot* get access to a local NTP server or other central sync source even if you threaten to throw money at them. Tamperproofness-wise, two miniature PCs with GPS receivers on a roof your provider owns and controls run circles around everybody and his VMs talking to public no-crypto NTP servers through a plain Internet uplink ...) Regards, J. Bern -- *NEU* - NEC IT-Infrastruktur-Produkte im <http://www.linworks-shop.de/>: Server--Storage--Virtualisierung--Management SW--Passion for Performance Jochen Bern, Systemingenieur --- LINworks GmbH <http://www.LINworks.de/> Postfach 100121, 64201 Darmstadt | Robert-Koch-Str. 9, 64331 Weiterstadt PGP (1024D/4096g) FP = D18B 41B1 16C0 11BA 7F8C DCF7 E1D5 FAF4 444E 1C27 Tel. +49 6151 9067-231, Zentr. -0, Fax -299 - Amtsg. Darmstadt HRB 85202 Unternehmenssitz Weiterstadt, Geschäftsführer Metin Dogan, Oliver Michel _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions