Re: Broadcom bge and 802.1Q vlan tags

On Tue, Oct 12, 2004 at 09:24:15AM -0400, Don Bowman wrote:
> 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_at_ 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.
> 
Yes, sure.  But you still won't be able to see the VLAN frame
in this case (because VLAN information is stripped in h/w).


Cheers,
-- 
Ruslan Ermilov
ru_at_FreeBSD.org
FreeBSD committer