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Date:      Mon, 14 Jan 2002 14:58:49 -0800
From:      Luigi Rizzo <rizzo@icir.org>
To:        chkno@dork.com
Cc:        freebsd-ipfw@FreeBSD.ORG
Subject:   Re: ip_dummynet.c:"*** OUCH! pipe should have been idle!"
Message-ID:  <20020114145849.A70496@iguana.icir.org>
In-Reply-To: <200201142246.g0EMkXC05128@chk.phattydomain.com>
References:  <20020114141539.A70340@iguana.icir.org> <200201142246.g0EMkXC05128@chk.phattydomain.com>

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> Rules 49 & 51 are in place because of my other issue.  By setting
> the pipe's queue value to less than 20 slots I can make rule 51
> count orders of magnitude more packets than rule 49.  I was wondering
> if this was standard behavior.  The problem seems to dissapear as
> long as I keep the pipe queue large.  See -questions for that thread.

I have an explaination for this.

When the queue overflows, you get an ENOBUFS error, which natd
detects and handles by retransmitting the packet at a later time
(not a very good idea, I'd say that natd should just drop the packet
in this case. The "fix" might be trapping the ENOBUFS error in
usr/src/sbin/natd.c:FlushPacketBuffer() and returning as if the
transmission was successful).

> > Also, if the problem is easily reproducible, please
> > let me know if you are interested in testing some patches
> 
> The OUCH event is not reproduceable.  It happened in the middle of
> the night, & has only happened once so far.

eh, then all i can say is wait and see if it happens again...
in the meantime i will have a closer look at the code.

> The large port range issue seems more related to ipfw than dummynet,

i am not sure what is the issue there... do thing work if you
reduce the upper limit to 65534 ? In this case it might just be
a problem with unsigned short comparisons...

	cheers
	luigi
-----------------------------------+-------------------------------------
  Luigi RIZZO, luigi@iet.unipi.it  . Dip. di Ing. dell'Informazione
  http://www.iet.unipi.it/~luigi/  . Universita` di Pisa
  TEL/FAX: +39-050-568.533/522     . via Diotisalvi 2, 56126 PISA (Italy)
  Mobile   +39-347-0373137
-----------------------------------+-------------------------------------

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