[ntp:questions] ntp client: keep all servers at startup

mike michael.no.spam.cook at wanadoo.fr
Wed May 4 16:15:27 UTC 2005


mayer at gis.net wrote:
> ----- Original Message Follows -----
> 
>>You might consider configuring the server as a broadcast server, and
>>the client as a broadcast client. That way the client will be
>>listening for incoming packets at startup. If none arrive, or the
>>server does not  respond, it should just stay in the listening mode.
>>So if the server  isn't up/responding it should not affect the
>>capability of the client to  aquire good time once the server is back
>>online.
>>
> 
> 
> It will not show up in the list of associations until the server is
> reachable, whether it's set up for broadcast or as a server. The daemon
> will keep trying at regular intervals until it's available, sets up
> the association and then looks to see where it fits within the other
> associations that it has. Just because it doesn't show up doesn't mean
> that it's not trying to reach it.
> 
> Danny
> 

That's what I thought. But in a quick test it did not appear to be the case.

ntp.conf test
# my DCF lashup
  server 127.127.28.0 # use the shared memory reference clock driver.
# two of the servers from ntp.org pool
server enigma.wiredgoats.com maxpoll 12
server mx2.gs.washington.edu maxpoll 12

pull the ether connection
stop/start ntpd
wait a bit (ntpdate times ot very slowly) and put back the ether cable:

run ntpq -p  in a 65sec cycle

Wed May  4 17:47:06 CEST 2005
      remote    refid      st t when poll reach   delay   offset  jitter
==============================================================================
*127.127.1.0 LOCAL(0)   10 l   41   64   17    0.000    0.000   0.001
  127.127.28.0 .DCF.      0 l   42   64   13    0.000   -6.200   4.467
............
  Wed May  4 18:05:16 CEST 2005
      remote           refid      st t when poll reach   delay   offset 
  jitter
==============================================================================
  127.127.1.0  LOCAL(0)  10 l   35   64  377    0.000    0.000   0.001
*127.127.28.0    .DCF.   0 l   35   64  177    0.000   -1.886  20.032

   So the two external servers don't get picked up (after  15mins)

   from the ntpq command interface

ntpq> lassociations
ind assID status  conf reach auth condition  last_event cnt
===========================================================
   1 36188  9024   yes   yes  none    reject   reachable  2
   2 36189  9624   yes   yes  none  sys.peer   reachable  2
ntpq>
ntpq>  lpeers
      remote           refid      st t when poll reach   delay   offset 
  jitter
==============================================================================
  LOCAL(0)        LOCAL(0)        10 l   59   64  377    0.000    0.000 
   0.001
*SHM(0)          .DCF.            0 l   60   64  375    0.000   -0.961 
18.930
ntpq>

   the pool.ntp.org servers are not listed

   But both are responding to queries: Heres one -
[mike at quark mike]$ ntptrace mx2.gs.washington.edu
mx2.gs.washington.edu: stratum 3, offset -0.000430, root distance 0.000755
omega.cac.washington.edu: stratum 2, offset 0.000120, root distance 0.000359
bigben.cac.washington.edu: stratum 1, offset -0.000008, root distance 
0.000000, refid 'USNO'




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