[ntp:questions] different request pattern

arne_woerner at yahoo.com arne_woerner at yahoo.com
Mon Jun 30 08:19:57 UTC 2008


hi!

when i  implemented my own ntp client, i found, that modern clocks
(acpi) have a quite stable drift... even when the cpu frequency
changes a lot...

so i could achieve quite good results with 5000 seconds between each
request and just one request at a time... with 5 servers i ask each
server once in 25000 seconds... if a server is a false ticker i can c
it when i compare the "offset per second" (ops) to previous ops of
this server and the other servers... i c typical offsets of below 10ms
using an adsl line with round-trip times of about 60ms...

wouldn't that help to reduce the load on the ntp servers?
at least if leaf nodes would do it like that (just in case that my
algorithm leads to less accurate time)...?

then i found that the official ntpd algorithm doesnt propagate false
tickers to its clients fast enough, so that they start building a
strange average offset (instead of overruling the bad source) and show
the old (false ticker) refid or even a completely messed up refid in
"ntpq -pn"... but possibly that server is not maintained so good,
although it is run by a university...

bye
arne




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