UDP packet loss

Rick Jones rick.jones2 at hp.com
Thu Jun 8 18:40:55 UTC 2006

Patrick Klos <pklos at osmium.mv.net> wrote:
> In article <e69ccs$cbm$1 at sf1.isc.org>, Pavel Urban  <urbanp at mlp.cz> wrote:
>>     948795842 packets received
>>     149802 packets to unknown port received.
>>     214635022 packet receive errors
>>     1003702082 packets sent
>>  I've tried to increase system udp receive buffer 10x and then 100x
>>  with no noticable effect. Do I have to change something in Bind,
>>  too? Or am I completely wrong?

> I'd say your biggest problem is the 214 million packet receive
> errors!  Find the source of those errors, and you'll likely take
> care of your problem.  Your machine is tossing 1 out of every 4 or 5
> packets!

IIRC, 99 times out of 10 those packet receive errors are the socket
buffer overflowing.

Now, to actually get a larger socket buffer, you may need to tweak the
sysctl settings _and_ something in the named config file.  Sysctl to
raise the limit and named config file to make sure that named doesn't
"undo" it by asking for something smaller.

However, that will only help if the issue is occasional bursts of
requests and the average request rate remains within the limits of the
server.  If the average request rate is higher than the server can
satisfy, no increase in the socket buffer will help.

rick jones
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

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