[ntp:questions] Re: where should we update sys_rootdispersion?

David L. Mills mills at udel.edu
Sat Sep 6 19:39:13 UTC 2003


Over the ten years since rfc-1305 some implementation details have
evolved, so don't treat the procedure functional description as
concrete. However, and as I restated in a recent message on this list,
the dispersion increases at constant rate, but is reset when a clock
update is received. Details are in the architecture briefing on the NTP
project page linked from www.ntp.org.

The usual cause of elevated dispersion is either dropped packets or no
updates received for a very long time.


donglingd at hotmail.com wrote:
> Hi,
>    could somebody let me know in which procedure we should update
> sys_rootdispersion? I saw some old code update sys_rootdispersion in
> clock_update procedure after calling clock_select() while ntpv4 code update
> this system veriable in local_clock(). Which one is correct?
>     I saw some how sys_rootdispersion is very big which cause all the
> packets send from this boxs are dropped by remote peer since header test8
> failed. I try to figure out how come sys_rootdispersion become that big.
> could anybode let me know how sys_rootdispersion is supposely caculated and
> update? what could be the cause?
> Thanks so much!
> -dongling
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