Date: Tue, 12 Oct 2004 21:51:29 +0300 From: Ruslan Ermilov <ru@freebsd.org> To: Sam Leffler <sam@errno.com> Cc: freebsd-current@freebsd.org Subject: Re: Broadcom bge and 802.1Q vlan tags Message-ID: <20041012185129.GA86935@ip.net.ua> In-Reply-To: <416BFE30.2090308@errno.com> References: <9256D57F598E6C41B288AA7DB94F29C902DFB963@pgnmail1.pgnaplikace.cz> <20041012140205.GD29433@cell.sick.ru> <416BFE30.2090308@errno.com>
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On Tue, Oct 12, 2004 at 08:54:24AM -0700, Sam Leffler wrote:
> Gleb Smirnoff wrote:
> >On Tue, Oct 12, 2004 at 10:36:27AM +0200, Roub?cek Zdenek (T-Systems=20
> >PragoNet) wrote:
> >R> I have run into a problem with my Broadcom NIC (Dell LATITUDE D600).=
I=20
> >am not able to detect 802.1Q tags on incoming interface with ethereal or=
=20
> >tcpdump. All incoming packets seems like they are not coming through tru=
nk=20
> >but as native ETH frames, ie. the vlan tag is missing, probably removed=
=20
> >before being passed to tcpdump?
> >R>=20
> >R> No I have not tested NIC's behaviour on 4.X, but I is working with=20
> >linux (2.6.something kernel probably?)
> >R>=20
> >R> Any ideas what to modify or set so I can detect vlan_tag would be ver=
y=20
> >apreciated.
> >
> >As Ruslan already mentioned, it is impossible to turn off hardware VLAN
> >stripping in bge driver.
> >
> >A patch to stop tagged frames to come on trunk interface is like this:
> >
> >@@ -701,13 +657,16 @@
> > * see if the device performed the decapsulation and
> > * provided us with the tag.
> > */
> >- if (ifp->if_nvlans &&
> >- m_tag_locate(m, MTAG_VLAN, MTAG_VLAN_TAG, NULL) !=3D NULL) {
> >+ if (m_tag_locate(m, MTAG_VLAN, MTAG_VLAN_TAG, NULL) !=3D NULL) {
> > /*
> > * vlan_input() will either recursively call ether_input=
()
> > * or drop the packet.
> > */
> >- KASSERT(vlan_input_p !=3D NULL,("ether_input: VLAN not=
=20
> >loaded!"));
> >+ if (vlan_input_p =3D=3D NULL) {
> >+ /* vlan(4) is not loaded, discard frame */
> >+ m_freem(m);
> >+ return;
> >+ }
> > (*vlan_input_p)(ifp, m);
> > return;
> > }
> >
>=20
> This pessimizes normal traffic.
>=20
m_tag_locate() doesn't look like a very expensive function. And
with the "normal traffic", I don't expect to be more than one tag,
no? Also, if if_nvlans > 0, this is already "pessimized".
> We should look for a solution in the=20
> driver(s) to avoid sending packets up with tags when no vlans are=20
> configured.
>=20
I'd be opposed to such a change in behavior. The VLAN consumer can
be not only vlan(4), it can equally be the ng_vlan(4) node, etc.
Cheers,
--=20
Ruslan Ermilov
ru@FreeBSD.org
FreeBSD committer
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