[ntp:questions] NTP request retry?

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Tue Jan 28 00:22:17 UTC 2014


On 2014-01-27 14:45, Rob wrote:
> Rick Jones <rick.jones2 at hp.com> wrote:
>> Brian Inglis <Brian.Inglis at systematicsw.ab.ca> wrote:
>>
>>> You don't specify which system and devices you are using,
>>> so here are a couple of articles about changing ARP timeouts:
>>> http://www.embeddedsystemtesting.com/2013/01/arp-timeout-value-for-linux-windows.html
>>> http://support.microsoft.com/kb/949589
>>
>> And if indeed these are all the OP's own systems, he can add
>> hardwired, "permanent" ARP cache entries via the arp command (under
>> most *nixes at least).
>
> I'm still not sure if ARP is really the problem, but fixing the
> clients to maxpoll 6 seems to cure it.
> (at least the reach now sticks at 377)
>
>> If a mix of wired and wireless is involved, if there is some way to get
>> traces at the point where the two join that would be goodness.
>
> If both would be WiFi, I would point at the WiFi.  However, one is
> connected to the wired network (a switch where the server is connected
> as well).
>
> I can ping it as much as I like, no loss:
> 1571 packets transmitted, 1571 received, 0% packet loss, time 20468ms
> rtt min/avg/max/mdev = 0.702/0.845/1.168/0.090 ms
>
> But when ntpd is allowed to climb to 1024-second polls, it gets almost
> no replies.

Check the server wrappers/firewall/switch allowing incoming unsolicited
packets on port 123. If you "enable stats"+"statistics rawstats" or watch
packets on the server, you should see whether requests are making it into
the server and replies out. As other posters have suggested, it could be
a port blocking timeout anywhere along either path between the two ntpds.

-- 
Take care. Thanks, Brian Inglis


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