[ntp:questions] Request throughput in ntp 4.2.4p7

David Mills mills at udel.edu
Thu Jul 2 13:43:39 UTC 2009


Breck,

I have no idea what version you may be using or what your operating 
system might be doing, but the current NTP version that leaves here has 
rate controls that by default purposely discard traffic from any single 
source of over eight packets per second. Flooding a victim server with 
5000 packets per second is an issue with the national laboratories, as 
reported in a recent paper, but not a factor in the public software 
distribution.

Dave

Breck Beatie wrote:

>I've been running ntp 4.2.4p4 on my desktop.  I recently upgraded to
>4.2.4p7
>and noticed that at high ntp request rates (5000 requests per second) it
>seems
>to drop a lot of requests.  With ntp 4.2.4p4 (as packaged by kubuntu
>maintainers)
>it would drop fewer than 0.02% of incoming requests.  That is up from a
>0.00%
>drop rate for 4.0.4p0 on the same hardware.  Now with 4.2.4p7 it's
>dropping
>2.65% of ntp requests.
>
>Has anybody else noticed the drop off in request throughput?  If so, is
>there
>any perception of a "problem"?
>
>Thanks in advance.
>
>
>Breck 
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