[c-nsp] NTP synchronization problems C2801

[Peter Rathlev]

On Wed, 2010-06-30 at 17:43 -0400, Rodney Dunn wrote:
> Can you try the iburst option to see if it changes it?

I tried adding "iburst", and though it behaves as expected by sending 8
rapid (~4 secs apart it seemed) after initialization I still end up
relatively unsynchronized:

 10.83.247.20 configured, authenticated, our_master, sane, valid, stratum 2
 ref ID 10.85.8.130   , time CFD638BF.C765F6DB (23:42:23.778 CEST Wed Jun 30 2010)
 our mode client, peer mode server, our poll intvl 64, peer poll intvl 64
 root delay 1.70 msec, root disp 25.60, reach 1, sync dist 30.50
 delay 0.92 msec, offset -14.8808 msec, dispersion 0.15
 precision 2**20, version 4
 org time CFD63B35.5F8F925C (23:52:53.373 CEST Wed Jun 30 2010)
 rec time CFD63B35.637A41FB (23:52:53.388 CEST Wed Jun 30 2010)
 xmt time CFD63B35.633885DA (23:52:53.387 CEST Wed Jun 30 2010)
 filtdelay =     0.98    0.95    1.58    1.41    0.99    0.93    0.92    0.94
 filtoffset =  -14.80  -14.81  -14.96  -15.05  -14.87  -14.88  -14.88  -14.88
 filterror =     0.00    0.03    0.06    0.09    0.12    0.15    0.18    0.21
 minpoll = 6, maxpoll = 10

That's from shortly after the initial burst ended. Status:

 Clock is synchronized, stratum 3, reference is 10.83.247.20  
 nominal freq is 250.0000 Hz, actual freq is 250.0256 Hz, precision is 2**24
 reference time is CFD63B2B.63AE2585 (23:52:43.389 CEST Wed Jun 30 2010)
 clock offset is -14.8808 msec, root delay is 2.63 msec
 root dispersion is 978.06 msec, peer dispersion is 0.15 msec
 loopfilter state is 'CTRL' (Normal Controlled Loop), drift is -0.000102725 s/s
 system poll interval is 64, last update was 13 sec ago.

> I don't see how going back to 24T would change it as it has v4 there 
> too...unless there was something later that made it even worse.

I tried to "harass" the 24T device as much as I could: delete NTP
config, reset drift file ("ntp clear drift"), set the clock to somewhere
in 1993 and reinsert config. It recovers (~10 usec offset) within
several minutes.

I'd like it to run 15.0M, so the downgrade is just to see if it makes
any difference.

-- 
Peter