[ntp:hackers] RE: Interpetation of RFC 1305 and NTP determination

Lister, John A [LTD] John.Lister at embarq.com
Thu Sep 21 16:18:45 PDT 2006


 
Quote from RFC1305

"However, when these servers are at approximately the same distance, the
computation may result in random selections among them as the result of
normal dispersive delays. Ordinarily, this does not degrade accuracy as
long as any discrepancy between the primary servers is small compared to
the synchronization distance. If not, the filter and selection
algorithms will select the best of the available servers and cast out
outlyers as intended."


Question I have:

We have two Stratum 2 NTP clocks (Server A, Server B) located similar distance from a Stratum 3 Client. 

*	Server A has a time of 11:11:01 
*	Server B has a time of 11:12:01

Stratum 3 Client comes on line with a time of 11:13:00.

 

Assuming the algorithm determines both server clocks are equal in value: Should Client disregard the servers since the times are not in sync and run stand alone, or pick one of the servers and synchronize?

My understanding:

1.	local clock is higher Stratum level 
2.	local clocks are considered to be "Last Resort"

The Client should pick a Server (Stratum 2) and synchronies. Most likely be Server B if all other implications are equal due to closer time from local.

 

Your feedback would be greatly appreciated.

 

Thank You

John Lister

Network Architect III

Embarq Corporation.



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