[ntp:questions] frequency adjusting only

David L. Mills mills at udel.edu
Fri May 2 17:58:27 UTC 2008


Brian,

The longest delay NTP response was from the Moon, as simulated at JPL. 
Next step is the Mars orbiters and then the rovers. JPL discovered the 
max distance threshold had to be increased to handle the Moon delay.

The longest lived NTP headbanger was when I used ARPAnet IMP 29 back in 
the late 70s. The banger continued without response until the ARPAnet 
was dismantled in the early 90s. There are folks that have been banging 
on our racket.udel.edu at its 128.4.1.1 address since 1981.

So far, not response has arrived before the request was sent. The code 
even checks for that. I'll let you know.

Dave

Brian Utterback wrote:

> David L. Mills wrote:
> 
>> Suspecting such could be the case between NTP servers and clients, I 
>> designed an experiment to detect such things and found small but 
>> significant LRD effects with lags up to TWO WEEKS! At short lags up to 
>> several network turns this can be explained by packet lengths, 
>> buffering, retransmissions, etc., but at much longer lags you have to 
>> look for routing flaps, provisioning changes, etc.
>>
> 
> Dave, are you saying that you saw an instance of a NTP response arriving 
> 2 weeks after the request was sent?
> 
> Brian Utterback




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