configure ntp on a cisco router

Discussion in 'Cisco' started by mikerinos2000, Feb 10, 2004.

  1. I want to syncronize 7206 router with an external ntp server.
    I have configured on my router
    ntp server NTP_SERVER_IP.
    set timezone MET 1
    I have been waiting for a time, but the time of the router it's wrong.
    I detail some features of cisco router.
    sh ntp associations
    address ref clock st when poll reach delay offset disp
    ~ 16 - 64 0 0.0 0.00 16000.
    ~ 16 - 64 0 0.0 0.00 16000.
    * master (synced), # master (unsynced), + selected, - candidate, ~ configured

    sh ntp status

    Clock is unsynchronized, stratum 16, no reference clock
    nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**18
    reference time is C3D2AEEA.41751DF6 (02:14:18.255 MET Tue Feb 10 2004)
    clock offset is 0.0000 msec, root delay is 0.00 msec
    root dispersion is 375.02 msec, peer dispersion is 375.02 msec

    There is something more I haven't configured.
    mikerinos2000, Feb 10, 2004
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  2. mikerinos2000

    Ivan Ostres Guest

    Send 'sho ntp assoc detail'. It looks like router can't talk to external
    server (maybe bad authentication?).
    Ivan Ostres, Feb 10, 2004
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  3. Set your clock on the router to be close to the actual time... I've seen
    where it won't sync if it's too far from the real time... that or

    Johnny Routin, Feb 10, 2004
  4. I have never seen that, actually. It would make NTP less than useful on
    boxes like 2500s, which have no backup clock and start decades in the
    past (Mar 1 1970?) after a reload.

    NTP will sync them just fine without having to set the clock manually first.


    M.C. van den Bovenkamp, Feb 10, 2004
  5. mikerinos2000

    Rod Dorman Guest

    By default the source IP address your packets go out with is that of
    the interface they're going out of. If that address isn't reachable
    from the NTP server you'll never get the response.

    Try adding a "ntp source" statement to see if it helps.
    Rod Dorman, Feb 10, 2004
  6. Is there any firewall?
    NTP works on UDP port 123 in both directions. It is necessary to
    permit incoming UDP traffic on that port.
    And try with NTP version 2 (default is 3).
    Juraj Ljubesic, Feb 11, 2004
  7. I have a cluster software. I have two nodes. The node I had configured
    it was the cluster, but It doesn't works. I must put a node as a
    server prefer and the other node as ntp server also.
    Thanks for all comments.
    mikerinos2000, Feb 11, 2004
  8. mikerinos2000

    Dave Katz Guest

    The software from which the cisco NTP was derived (xntpd) indeed will
    not step the clock more than a couple of minutes, as a paranoid robustness
    measure. However, given that the only cisco machine with a $2 digital
    watch chip and battery at the time was the 7000, the vast majority of
    systems woke up thinking it was March 1 1993 and thus required the time
    to be stepped by a large amount. So the step limiter was removed.
    Dave Katz, Feb 12, 2004
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