[ntp:questions] very slow convergence of ntp to correct time.

Eric nospam-01 at jensenresearch.com
Mon Jan 28 20:02:20 UTC 2008

On Mon, 28 Jan 2008 19:19:12 +0000, "David L. Mills" <mills at udel.edu> wrote
for the entire planet to see:

>Many years ago the Proteon routers dropped the first packet after the 
>cache timed out; that was a disaster. That case and the ones you 
>describe are exactly what the NTP burst mode is designed for. The first 
>packet in the burst carves the caches all along the route and back. The 
>clock filter algorithm tosses it out in favor of the remaining packets 
>in the burst. No ICMP is needed or wanted.

I agree about ICMP.  UDP would be better.

And BURST / IBURST are nice, but conventional wisdom has it that BURST
really shouldn't be used towards servers that you don't administer, and
IBURST will of course not handle the ongoing case.  

In considering this more, I think a great option or tinker value would be
one that simply sends an extra packet, rather than eight of them, and only
if the previous poll for that association was sent more than x seconds ago.
In other words, as long as the poll value is say 7 or less, nothing new is
needed.  When the poll exceeds 7, then ten seconds before a poll is due to
be sent an "explorer" poll is sent (and any response would likely be
discarded).  EBURST, or maybe PAVE.

- Eric

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