[ntp:hackers] Does ntpd need to whine more ?

Poul-Henning Kamp phk at phk.freebsd.dk
Mon Oct 3 10:45:02 UTC 2005

In message <43410902.nailKAX17KIJN at mini-me.trailing-edge.com>, Tim Shoppa write
>> I'm also wondering the wisdom of not slamming the poll rate back
>> to 64 seconds when the shift register runs empty.
>Slamming back to minpoll when a host becomes unreachable is a fairly
>evil behavior (and also one that OpenNTPD has).  What good does
>polling a sick host (either broken, or nonresponsive due to network
>difficulties) more often do?

First: you don't have to slam it back down until it replies first time.

Second: do the math and you can see your argument is bogus:

10000 hosts at 1/64 seconds = 156 packets/second. (< 100kbit/sec).

If you host cannot deal with that, it has no business being A NTP
server (any more ?).

>If you implicitly do not trust the PLL behavior of tuning local drift,

I _explicitly_ do not trust NTPDs PLL, and have therefore written my
own But that is an entirely different matter.

This is about how long time a client spends after reachability is
restored before the clock is locked again (and wether it should
have told you more loudly that it had lost reachability).

Several hours is waayy too long IMO.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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