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Date: Thu, 17 Apr 2003 20:50:30 -0400 (EDT)
From: Garrett Wollman <wollman@lcs.mit.edu>
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To: Brooks Davis <brooks@one-eyed-alien.net>
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cc: freebsd-net@freebsd.org
cc: freebsd-stable@freebsd.org
Subject: Re: vlan0 on em0 has mtu 1496
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<<On Thu, 17 Apr 2003 17:19:04 -0700, Brooks Davis <brooks@one-eyed-alien.net> said:

> Because the vlan header takes up 4 bytes.  With em(4) devices it looks
> like fixing that should be a simple matter of raising the real
> interface's MTU to 1504.

Actually, the parent interface's MTU should not be touched.  The
link-layer header length is what needs to be increased.

-GAWollman