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Date:      Tue, 12 Oct 2004 09:24:15 -0400
From:      "Don Bowman" <don@sandvine.com>
To:        "Ruslan Ermilov" <ru@FreeBSD.org>
Cc:        Gleb Smirnoff <glebius@FreeBSD.org>
Subject:   RE: Broadcom bge and 802.1Q vlan tags
Message-ID:  <A8535F8D62F3644997E91F4F66E341FC9E34F8@exchange.sandvine.com>

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From: Ruslan Ermilov [mailto:ru@FreeBSD.org]
> On Tue, Oct 12, 2004 at 08:32:38AM -0400, Don Bowman wrote:
> > Roub?cek Zdenek:
> > >=20
> > >  Hello current
> > >=20
> > >  I have run into a problem with my Broadcom NIC (Dell=20
> > > LATITUDE D600). I am not able to detect 802.1Q tags on=20
> > > incoming interface with ethereal or tcpdump. All incoming=20
> > > packets seems like they are not coming through trunk but as=20
> > > native ETH frames, ie. the vlan tag is missing, probably=20
> > > removed before being passed to tcpdump?
> >=20
> >  ...
> >=20
> > do you have if_vlan loaded? try 'kldload if_vlan'.
> > This happens automatically if you create a vlan interface, but
> > you may not have one if you are just sniffing.
> >=20
> There appears to be a bug with drivers that support VLAN tag
> striping in hardware in case no VLAN interfaces are configured.
> In this case, ether_demux() will just proceed like if it was
> an untagged Ethernet frame.  glebius@ promised to fix this bug.
>=20
> Zdenek, unfortunately, the bge(4) driver doesn't allow the
> user to disable hardware vlan tag striping (like, e.g., the
> em(4) driver allows), so you cannot watch VLAN frames on this
> box using tcpdump or ethereal.

I believe you can work around it by creating a vlan interface,
even if not connected.
that is, if its the same bug that i've run into with em.



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