nanog mailing list archives

Re: GPS WNRO April 6th at GPS Midnight


From: Stephen Satchell <list () satchell net>
Date: Thu, 4 Apr 2019 05:16:24 -0700

On 4/3/19 3:32 PM, brutal8z via NANOG wrote:
I've not seen any mention of this here, so it might be off-topic, if so,
sorry in advance. If you use GPS for time synchronization, this might be
important.The Juniper ACX500 series and the Cisco 819 both have an
embedded GPS receivers, for example.

At 23:59:42 UTC on 4/6/2019 (Midnight GPS time, which differs by 18
leap-seconds <https://en.wikipedia.org/wiki/Leap_second> from UTC) , the
10-bit GPS Week Number broadcast by the constellation will reset to zero
for the second time since the beginning of GPS on 1/6/1980.

There was a mention of this a couple of weeks ago, as a "heads-up".

When it first appeared up here, I checked with the vendor of my GPS time
appliances.  The vendor told me that the testing they did of their
product showed no issues with the roll-over for specific ranges of
serial numbers.  Mine is within one of the ranges.

The proof of the pudding will be what happens at 5pm PDT on my birthday,
April 6, and what ntpq reports on my edge server.


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