Question for those who run a local NTP server

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Question for those who run a local NTP server

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NAS
RS1221+, RS819, RS217
Operating system
  1. macOS
Mobile operating system
  1. iOS
My ancient ntp server had to go a while back due to its size and power consumption. In recent days I bought a new modern ntp server which is GPS+PPS bound but no heater or stabilised crystal.

My new ntp server (an ebay bargain) does not offer its own fallback external servers, so I am configuring them on my router. However, I have run into a few snags in the effort to configure a genuine fallback-only external ntp set. For routine use I do not wish for any external ntp traffic unless the internal one has failed.

In the past I could achieve my aim by using the "true" statement on my own ntp, which pinned the snowflake on the correct address and the external providers remained dormant. Back then the "prefer" statement did little to prevent the snowflake moving to the best "+" server and blending the results.

The "True" statement doesn't seem to work (at least for my Debian router) - it accepts the statement but nothing seems to change and all servers, internal & external, remain in regular use. I'm not sure if the absence of a RTC in my router is influencing the "true" statement or not.

In better news the "prefer" statement now works perfectly and pins the snowflake as intended and the stratum 1 pps is the master clock. Great for accuracy and redundancy but still has ntp packets traversing the WAN when not needed or desired.

My own ntp server snowflaked (partially redacted address) along with the other curated/resilient external stratum 1 mix, feeding my router and my wider network:

20210801-NTP Server Via ER-4.jpeg


The rather sparse ntp status once trained and settled:

20210801-TimeNet Pro Status.png


NTP Server Configuration (10.0.1.50 is my internal ntp):

Code:
name-server 127.0.0.1
    ntp {
        server 10.0.1.50 {
            prefer
        }
        server ntp.se {
        }
        server time.euro.apple.com {
        }
        server time.google.com {
        }

Any thoughts or settings I could try to achieve fallback-on-fail-only on my ntp sources and keep my internal ntp as the sole server at all other times?

:coffee:
 
Nope. But interested.

Years ago I had to look into proposing one in a fully isolated network. Back then it was to use radio time signals: that would be from Rugby in UK, amongst other places. Meant considering getting an aerial installed into a data room. I guess the GPS wiring ends up as an up to date version of the same.
 
Thanks @fredbert - a very small club then!

I acquired my first NTP server from an old fully-isolated network and it too was bound to MSF. Prices are still as stupid as ever. Even my new GPS/PPS unit has a retail of £800 but can be found a bit cheaper.

I spotted this new one on ebay as the chap was selling 5 new units for £150 each, or make an offer... to which we settled on just £100 (!) so was relieved and happy to actually receive a brand-new-in-box item.

One heck of a discount!

Learned / re-learned a good deal about NTP along the way; I think I had the full suite of things not to do, including the use of DNS, pools etc. My NTP setup is now resilient, redundant, diverse and is not relying on other protocols:

Code:
remote           refid           st t when poll reach   delay   offset  jitter
==============================================================================
*10.0.1.50       .PPS.            1 u   64  256  377    0.265   -0.022   0.022
+17.253.34.251   .SHM.            1 u   46  256  377   15.818    0.920   0.340
+17.253.34.253   .SHM.            1 u   45  256  377   15.881    1.002   0.307
+45.66.39.122    .PPS.            1 u   46  256  377   20.682    0.485   0.384
+139.143.5.30    139.143.45.169   2 u   58  256  377   16.810    1.123   0.219
+139.143.5.31    139.143.45.169   2 u   30  256  377   16.893    1.070   0.262
+2a01:3f7::1     .PPS.            1 u   39  256  377   31.737    1.034   0.331

Code:
name-server 127.0.0.1
    ntp {
        server 10.0.1.50 {
            prefer
        }
        server 17.253.34.251 {
        }
        server 17.253.34.253 {
        }
        server 45.66.39.122 {
        }
        server 139.143.5.30 {
        }
        server 139.143.5.31 {
        }
        server 2a01:3f7::1 {
        }
    }

Not found a pure fallback mode yet, so the extra NTP packets are going external but not being used unless the internal GPS and PPS are both down.
 
The ebay listing is still going and I appear to have been the only buyer so far. If anybody else is looking for a bargain or just to beat my £100 offer:


Clearly I have no association with the seller other than buying from him.
 
Seems more sensitive with a powered antenna and the data sheet says it is designed for it. Mine is, for the moment, sitting on a windowsill behind a wooden frame and double glazing:

Windowsill Antenna.JPG


Signal is fine:
GPS Signal Windowsill.png


Current location will not pass the longterm approvals stage though. I may put the antenna in the loft and utilise some unused TV coax to bring the signal down close to an existing ethernet port, or just put the whole lot in the loft with an additional PoE cable to the switch.

Next time I have an antenna guy around I will probably get him to put one of those combined GSM/3/4/5G/GPS/WiFi etc hockey-pucks on the existing tv / sat antenna masts. I'm not one for crawling around on 45deg tiled roof...:eek:
 

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