[ntp:questions] NNTP server causing large jumps in time

Dave foo at coo.com
Wed May 7 07:47:46 UTC 2008


Dave wrote:
> David Woolley wrote:
>> Dave wrote:
>>> Looking at the logs on my Sun Blade 2000 running Solaris 10, I see 
>>> numerous occasions on which the time has been stepped. Looking at the 
>>> few only (today, 1/5/2008), I see it was stepped around +0.3 sec at 3 
>>> AM, then -0.4 at 4:30 am, then half an hour later at 5am it was moved 
>>> -0.6 sec, then 40 minutes later it is moved another -0.6 sec. Since 
>>> then (its now 1:30 pm), it has not changed.
>>
>> Positive and negative steps which approximately balance each other 
>> indicate a heavily loaded link with variable and asymmetric 
>> propagation delays.  Apart from local servers, or your Rubidium PPS, 
>> or reducing the traffic, the other solutions are to apply and get the 
>> ISP to apply traffic shaping to prioritise NTP traffic, or to use the 
>> tinker huff and puff option, noting the health warnings attached to it.
> 
> 
> I've changed to local servers as suggested
> 
> server 0.uk.pool.ntp.org
> server 1.uk.pool.ntp.org
> server 2.uk.pool.ntp.org
> server 3.uk.pool.ntp.org

I meant to add that perhaps an overloaded network is the problem. The 
machine only has a 256 kb/s uplink (1024 kb/s downlink), and is used as 
a web server for a small number of little used domains. Perhaps this is 
putting too much strain on it. I occasionally download large files (like 
iso images of Solaris), so I'll check if things get worst next time I do 
that.




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