[c-nsp] NTP not synchronizing

Aaron R aaronis at people.net.au
Mon Sep 15 08:11:50 EDT 2008


I have had similar problems in the past. I have found if your clock / date
are not set properly the router will refuse to accept the NTP update as the
offset is too large.

Also as suggested try multiple NTP servers. The fact that you are unable to
see the configured NTP servers' ref clock / stratum most likely indicates
some kind of comms issue. 

Cheers,

Aaron.



-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Mike Louis
Sent: Monday, September 15, 2008 7:40 PM
To: root net; Velasquez Venegas Jaime Omar
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] NTP not synchronizing

What source interface is the cisco client router using for NTP requests? If
its not configured it will use the outbound interface used to reach the
server. I saw an issue the other day where the external interface on the WAN
was not reachable by the NTP server at the home office and thus they could
not sync time. They changed the source interface to "ntp source-interface
Fax/x" (for their lan which was reachable) and were able to get sync'd.

HTH

Mike

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of root net
Sent: Monday, September 15, 2008 12:17 AM
To: Velasquez Venegas Jaime Omar
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] NTP not synchronizing

What NTP server are you using?  Are you trying to use the Cisco router as
the NTP server for your clients/hosts on your network or what?  My bet is
the NTP server is overwhelmed you are trying to connect to.  I had this
issue before and changed NTP servers worked like a charm.  Check the NIST
listing for an updated listing of NTP servers that are free or with little
users.

rootnet

On Sat, Sep 13, 2008 at 1:30 PM, Velasquez Venegas Jaime Omar <
Jaime at ulima.edu.pe> wrote:

> Hi there.
>
> I'm having a problem trying to synchronize a Cisco Router across a wan
> link with a NTP Server (No-Cisco router).So far i've ruled out packet
> filering or firewall blocking as a cause of this.Some other equipments
> at the local side of this router actually synchronize with the ntp
> server at our LAN.What strikes me is the fact that router does reach ntp
> server via other protocols other than ntp tough.
>
>
> This is what i get from the out-of-sync router:
> #Show ntp assoc
>     address         ref clock     st  when  poll reach  delay  offset
> disp
> ~<<NTPServer>>    0.0.0.0          16     -    64    0     0.0    0.00
> 16000.
> * master (synced), # master (unsynced), + selected, - candidate, ~
> configured
>
> I've set debugging for the ntp packets and for all the traffic getting
> out of the serial interface which got "NTP: xmit packet to NTP.Server"
> events.However there 's absolutely no attempt whatsoever of packet being
> transmitted to NTP Server at the serial interface.
> I've also configured this router as a ntp master and tried to get the
> hosts on its local ethernet to synchronize with it to no avail.
>
> Any insight?
>
> Thanks
>
>
>
>
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