[comp.protocols.time.ntp] Clockhopping

hebo@MBARI.ORG (Bob Herlien) (05/23/91)

What would cause an erstwhile stratum-1 host to change its reference
from its own reference clock to an external stratum-1, thus converting
itself to stratum 2?

Situation: xntp running on a supermini (HP 850) and all workstations
(HP 350 class).  850 has a PSTI 1030 clock.  Lately, the 850 has hopped
to an external stratum-1, even tho the PSTI is shown as stratum 0 *and*
the dispersion and offset to the PSTI are lower than any external host.

I looked through the version 2 spec (my printed copy is August '89,
probably not the latest).  Section 4.2, "Clock selection procedure",
was no help, since it states that to make to the candidate list
"peer.stratum must be greater than zero", and the reference clock
is exactly stratum 0.  So by my reading, you'll never sync to your
own reference clock.  This is clearly false.

Can somebody give me a quick rundown on how clock selection *really* takes
place?  And any thoughts on why we're losing sync with our PSTI?
Is it coincidental that, suddenly, there are several new machines that
I haven't seen before that are ticking with us?

advTHANKSance.

-----------------------------------------------
Bob Herlien
MBARI (Monterey Bay Aquarium Research Institute)
hebo@hp850.mbari.org