[time-nuts] Google public NTP service

Chris Albertson albertson.chris at gmail.com
Thu Dec 1 00:09:31 EST 2016

On Wed, Nov 30, 2016 at 12:14 PM, Gary E. Miller <gem at rellim.com> wrote:

> Yo Michael!
> On Wed, 30 Nov 2016 14:21:39 +0000
> Michael Rothwell <michael at rothwell.us> wrote:
> > ... was just announced.
> > https://cloudplatform.googleblog.com/2016/11/making-
> every-leap-second-count-with-our-new-public-NTP-servers.html?m=1
> I sort of see where they are coming from, but this will cause problems.
> The NTP packets google sends out have no way to be marked as 'not UTC'.
> Given how promiscuous people are sharing NTP chimers these 'not UTC'
> chimers will get into the mix.  When they diverge from the real UTC servers
> it will sorely confuse NTP clients.

No, not confused at all NTP is designed to detect this problem.   The
Google servers will be detected as "False Tickers" and ignored.   Of course
some clients might be configured to look ONLY at Google servers but those
people like did that on purpose because they wanted to wrong time.   Anyone
with a normal NTP client that uses several different servers will be fine.

The for people who don't know how Ntp works, it is simple:  If you (a
human) ask a bunch of people "what time is it?" you would expect them all
to give you the same answer (within the precision of their wrist watches)
and if one person tells you something that is very different from everyone
else.  You do NOT become confused you just say to yourself "His watch must
be wrong,"  then you ignore his answer."   NTP clients do about this same
thing.   This is why we configure our NTP clients to query a wide and
diverse group of servers, so as to detect problems.   So,.. Google will not
poison the pool e of NTP servers, Google's incorrect time will not
propagate very far.

> I would support an RFC to mark the type a time an chimer is servings.
> Not only smeared and UTC, but also TAI, UT, UT0, UT1, UT2, ET, TDT, TDB,
> TT, TCG, TCB, GPS, etc...

No,  that is the wrong way to do it.  Then no one flavor of time has enough
servers to make the system work.  A better way is to agree that all NTP
servers use UTC and then distribute the corrections from UTC to the other
flavors and those who need to to the conversions can do so.

> ------------------------------------------------------------
> ---------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>         gem at rellim.com  Tel:+1 541 382 8588
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Chris Albertson
Redondo Beach, California

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