[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: time resolution (was Re: six-page binary format draft)

-----Original Message-----
From: Carl Ellison <cme@cybercash.com>
To: Paul Leyland <pcl@sable.ox.ac.uk>
Cc: apb@iafrica.com <apb@iafrica.com>; spki@c2.net <spki@c2.net>
Date: Monday, November 24, 1997 11:28 AM
Subject: time resolution (was Re: six-page binary format draft)

>There is no global spacetime.  It is not possible to synchronize clocks.
>The closest we can come to that is with error limits, given our knowledge
>the minimum and maximum delay in getting a time report.  If there were the
>master atomic clock on the net that still doesn't give us sub-second
>resolution of time setting.
>On the other hand, we can be reasonably sure of getting clocks to agree +/-
>30 seconds, so maybe 1 minute resolution of times would be appropriate.
> - Carl

Huh?  You are joking right?

My experience is that NTP stratum 2 and 3 clocks tend to be no more than 30
ms off from the naval observatory masters.  If you are using certs for
people centric stuff then your 30 seconds is probably good enough.  If you
start doing oltp stuff then clock sync becomes much more of an issue.

I agree the there is a danger in having more precision represented in the
data than exists in the source, but to arbitrarily cut the allowable
precision because today we can't sync clocks is crazy.  Didn't this whole
thing start around the fact that the binary format would break in 2106?  110
years from now we will probably be able to sync clocks!