Recommendation on NTP appliances/devices

Anyone have recommendations on NTP appliances; i.e. make, model, gps vs
cell, etc.? Roof/outdoor/window access not available. Would ideally
need to be able to handle bursts of up to a few thousand simultaneous
queries. Needs IPv6 support.


Without roof access I'd suggest CDMA instead of GPS:

  Appears to fit your requirements.


The downside of CDMA is it's going to live until Verizon & Sprint can
get enough of their customers migrated to LTE.

It really depends on how accurate you need to be.

If you only want <10ms accuracy but stable (It's trivial to get all
clients better than 1ms) then grab three to five old servers (or new
low-power ones), and just put ntpd on them, pointing at some nearby

If it *must* be an appliance the Symmetricom units are nice, and support
IPv6 (have done for years).

For some diversity you could try:

- WWVB/CHU radio with a good indoor antenna into an appliance
- CDMA, which yes is based on GPS, but tied with Rb oscillator can carry
   over any reception outages (CDMA or GPS)
- Of course just setup an NTP server that peers to
   (but perphaps the least desirable)

I've seen good results using the Endrun CDMA units as well as the
WWVB units, both appliances and IPv6-enabled. Symmetricom does this too.