[ntp:questions] Trouble creating symmetric connection

Henning Makholm henning at makholm.net
Wed Mar 7 16:01:02 UTC 2007


I have trouble getting two ntp servers to peer with each other.
What I do is first

  ntpdc -c 'restrict B.B.B.B 255.255.255.255 nomodify notrap' A.A.A.A
  ntpdc -c 'restrict A.A.A.A 255.255.255.255 nomodify notrap' B.B.B.B 

after which ntpdc -creslist echoes back appropriate restrict lines
with the only flags being nomodify and notrap - so I'm reasonably sure
that the servers do allow each others as peers, and that my remote
configuration commands are being carried out. Now:

  ntpdc -c 'addpeer B.B.B.B' A.A.A.A

and wait a few minutes for packets to be exchanged; then

  ntpdc -c peers A.A.A.A
  ntpdc -c peers B.B.B.B

After this A.A.A.A does list B.B.B.B as an association in
'symmetric-active' mode, and it appears to get nontrivial time
variables over this association, som B.B.B.B must be answering.

However, I had expected that B.B.B.B would list A.A.A.A as an
association in 'symmetric-passive' mode, but it doesn't. Shouldn't it?
The peer listing of B.B.B.B does not mention A.A.A.A at all.

Furthermore, if I unconfigure all of the servers the B.B.B.B used
to get time from, it will eventually revert to its undisciplined
local clock at stratum 13, rather than use the stratum-4-or-so time
it could have gotten from A.A.A.A. So it's actually not recognizing
A.A.A.A as a peer; it is not just the ntpdc listing that is buggy.

Both servers run Debian 'sarge' with its default ntp-server package.

I suspect I'm missing something really basic, but what? I have read
the ntp documentation and googled many possible search-term
combinations to no avail.

-- 
Henning Makholm  "Det er jo svært at vide noget når man ikke ved det, ikke?"




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