[ntp:questions] NTP request retry?

Charles Elliott elliott.ch at verizon.net
Tue Jan 28 03:05:37 UTC 2014


Have you considered the possibility that the computer has an "energy saver"
NIC, 
and NTPD activity is insufficient to wake it?

C Elliott

-----Original Message-----
From: questions-bounces+elliott.ch=verizon.net at lists.ntp.org
[mailto:questions-bounces+elliott.ch=verizon.net at lists.ntp.org] On Behalf Of
Rob
Sent: Monday, January 27, 2014 1:11 PM
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] NTP request retry?

Marco Marongiu <brontolinux at gmail.com> wrote:
> On 01/26/2014 08:08 PM, Rob wrote:
>> My hypothesis is that the ARP entry for the NTP server has timed out, 
>> and when ARP has to resolve an entry in some implementations the 
>> first packet is always lost (it is not cached pending a reply).
>> When the cycle is 1024 seconds, the ARP entry has again timed out the 
>> next poll cycle and the issue is the same.
>
> If you believe that it is the problem, and you own the servers you're 
> polling, then you may set maxpoll so that the polling interval is 
> always smaller then the ARP cache timeout.

Despite lots of tracing I still cannot really pinpoint the problem.

The only thing I see is that ping has absolutely zero loss and all usual
protocols work fine, but ntp indicates a high loss when there is no other
network activity.

When the network is kept busy, ntp works fine as well.
Very strange.

However, I do not like to "fix" it by increasing frequency, it may not even
help.  I'd like to have some "burst until there is a reply, up to X tries"
option.
It appears to be a function of other NTP clients, but not of ntpd.

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