On 2014-01-24 10:42, William Unruh wrote:
On 2014-01-23, David Woolley <[email protected]> wrote:
On 23/01/14 13:06, Marco Marongiu wrote:
3) second filter: a new value for the error that fits the majority of
these C references is calculated; the L references that don't fit in
this error interval are called "outlyers"; the S=C-L references that
remain are considered;
Ones that don't fall within the the largest mutually consistent set of
error bounds are called "false tickers", not "outlyers".
4) peer selection: among the references in S, the one that has the
smallest dispersion is selected, and ntpd will "follow" it until the
next evaluation of the data collected from the sources.
This is used for the figurehead peer that defines the stratum and error
statistics. All the ones that are valid and not outlyers or false
tickers will be tracked for time synchronisation purposes. (The is a
hysteresis mechanism that means that the system peer will not change as
often as the description implies.)
Does it use the time from that one, or some sort of "average"? Since the
queries of the different servers occur at different times (separated by
about and hour, given the initial filter at poll 10) how does it take the
averagei
if it uses the average?
Every packet received goes thru the processes below and may update the system
clock.
[adapted from How NTP Works
http://www.eecis.udel.edu/~mills/ntp/html/warp.html#arch]
NTP Software Architecture
Remote Peer/Poll System Clock
Servers Processes Process Discipline
Process
+--------+. +-----------+. +------------+ .
| |->| |. | | .
|Server 1| |Peer/Poll 1|->| | .
| |<-| |. | | .
+--------+. +-----------+. | | .
. ^ . | | .
. | . | | .
+--------+. +-----------+. | | +-----------+.
| |->| |. | Selection |->| |. +------+
|Server 2| |Peer/Poll 2|->| and | | Combine |->| Loop |
| |<-| |. | Cluster | | Algorithm |. |Filter|
+--------+. +-----------+. | Algorithms |->| |. +------+
. ^ . | | +-----------+. |
. | . | | . |
+--------+. +-----------+. | | . |
| |->| |. | | . |
|Server 3| |Peer/Poll 3|->| | . |
| |<-| |. | | . |
+--------+. +-----------+. +------------+ . |
...................^.........................................|.....
| . V
| . +-----+
+--------------------------------------| VFO |
+-----+
Clock
Adjust
Process
--
Take care. Thanks, Brian Inglis
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