Broadcom bge and 802.1Q vlan tags

Don Bowman don at sandvine.com
Tue Oct 12 06:24:17 PDT 2004


From: Ruslan Ermilov [mailto:ru at FreeBSD.org]
> On Tue, Oct 12, 2004 at 08:32:38AM -0400, Don Bowman wrote:
> > Roub?cek Zdenek:
> > > 
> > >  Hello current
> > > 
> > >  I have run into a problem with my Broadcom NIC (Dell 
> > > LATITUDE D600). I am not able to detect 802.1Q tags on 
> > > incoming interface with ethereal or tcpdump. All incoming 
> > > packets seems like they are not coming through trunk but as 
> > > native ETH frames, ie. the vlan tag is missing, probably 
> > > removed before being passed to tcpdump?
> > 
> >  ...
> > 
> > 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.
> > 
> 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.
> 
> 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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