MC0FRED writes:
> with reference to the other NTP servers I am usually within +/- 2ms of them.
> Any ideas why the pool server thinks I am ~12ms off?

All your NTP times come from network connections. Network connections have 
latencies.

Typical latencies on the global network range from microseconds (local) to 
milliseconds (not far away) to 100ms+ (farther away or skinnier pipe).

NTP makes a simple assumption that the latency is symmetric, that the transmit 
path and receive path both have the same latencies.

>From the consistent 12ms offset that the NTP pool server sees, there is some 
>kind of asymmetric latency going on.

Asymmetric latency can be related to assymetric signaling (e.g. ADSL) but you 
don't expect traffic to be so flat to give such a consistent 12ms delay.

You might check locally, if you have any very complex routing or firewall rules 
that may in fact be adding this latency in one direction. It is unusual for the 
latency to be so consistently 12ms.

NTP local clocks can also have intentional delays added (e.g. fudge flags in 
ntpd.conf) but this seems unlikely.

Tim.
_______________________________________________
pool mailing list
[email protected]
http://lists.ntp.org/listinfo/pool

Reply via email to