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Date: Thu, 6 Feb 2014 11:02:46 -0800
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Subject: Re: Errors using span interface on if_bridge(4)
From: hiren panchasara <hiren.panchasara@gmail.com>
To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>,
 Jack F Vogel <jfv@freebsd.org>
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On Sun, Feb 2, 2014 at 11:25 PM, hiren panchasara
<hiren.panchasara@gmail.com> wrote:

<skip>

> If I start tcpdump on
> interface again, the dev.ix.3.mac_stats.checksum_errs starts going up.
> Stopping tcpdump would stop the counter from incrementing.
>
> Why is that happening? I have no clue. How/why is tcpdump affecting
> this interface traffic stats in such a way?

Found the reason:

http://www.wireshark.org/faq.html#q11.1
http://sandilands.info/sgordon/segmentation-offloading-with-wireshark-and-ethtool

Putting an end to arguably the longest monologue on -net :-)

cheers,
Hiren