Re: [EXT] Re: [PATCH v6 3/3] net: dsa: ocelot: Add support for QinQ Operation

[Vladimir Oltean <olteanv@gmail.com>]

Hi Hongbo,

On Thu, Sep 17, 2020 at 02:37:59AM +0000, Hongbo Wang wrote:
> > On Wed, Sep 16, 2020 at 10:28:38AM +0000, Hongbo Wang wrote:
> > > Hi Vladimir,
> > >
> > > if swp0 connects with customer, and swp1 connects with ISP, According
> > > to the VSC99599_1_00_TS.pdf, swp0 and swp1 will have different
> > > VLAN_POP_CNT && VLAN_AWARE_ENA,
> > >
> > > swp0 should set VLAN_CFG.VLAN_POP_CNT=0 &&
> > VLAN_CFG.VLAN_AWARE_ENA=0
> > > swp1 should set VLAN_CFG.VLAN_POP_CNT=1 &&
> > VLAN_CFG.VLAN_AWARE_ENA=1
> > >
> > > but when set vlan_filter=1, current code will set same value for both
> > > swp0 and swp1, for compatibility with existing code(802.1Q mode), so
> > > add devlink to set swp0 and swp1 into different modes.
> >
> > But if you make VLAN_CFG.VLAN_AWARE_ENA=0, does that mean the switch
> > will accept any 802.1ad VLAN, not only those configured in the VLAN database
> > of the bridge? Otherwise said, after running the commands above, and I send a
> > packet to swp0 having tpid:88A8 vid:101, then the bridge should not accept it.
> >
> > I might be wrong, but I thought that an 802.1ad bridge with
> > vlan_filtering=1 behaves the same as an 802.1q bridge, except that it should
> > filter VLANs using a different TPID (0x88a8 instead of 0x8100).
> > I don't think the driver, in the way you're configuring it, does that, does it?
>
> hi Vladimir,
> you can refer to "4.3.3.0.1 MAN Access Switch Example" in VSC99599_1_00_TS.pdf,
> By testing the case, if don't set VLAN_AWARE_ENA=0 for customer's port swp0,
> the Q-in-Q feature can't work well.
>
> In order to distinguish the port for customer and for ISP, I add devlink command,
> Actually, I can modify the driver config directly, not using devlink,
> but it will be not compatible with current code and user guide.

I asked this on the Microchip Support portal:

-----------------------------[cut here]-----------------------------

VLAN filtering only on specific TPID
------------------------------------

I would like to configure a port with the following behavior:
- The VLAN table should contain 802.1ad VLANs 1 and 10. VLAN ingress filtering
  should be enabled.
- An untagged frame on ingress should be classified to 802.1ad (TAG_TYPE=1)
  VLAN ID 1 (the port-based VLAN). The frame should be accepted because 802.1ad
  VLAN 1 is in the VLAN table.
- An ingress frame with 802.1Q (0x8100) header VLAN ID 100 should be classified
  to 802.1ad (TAG_TYPE=1) VLAN ID 1 (the port-based VLAN). The frame should be
  accepted because 802.1ad VLAN 1 is in the VLAN table.
- An ingress frame with 802.1ad (0x88a8) header VLAN ID 10 should be classified
  to 802.1ad (TAG_TYPE=1) VLAN ID 10. The frame should be accepted because
  802.1ad VLAN 10 is in the VLAN table.
- An ingress frame with 802.1ad (0x88a8) header VLAN ID 100 should be
  classified to 802.1ad (TAG_TYPE=1) VLAN ID 100. The frame should be dropped
  because 802.1ad VLAN 100 is not in the VLAN table.
How do I configure the switch to obtain this behavior? This is not what the
"Provider Bridges and Q-in-Q Operation" chapter in the reference manual is
explaining how to do. Instead, that chapter suggests to make
VLAN_CFG.VLAN_AWARE_ENA = 0. But I don't want to do this, because I need to be
able to drop the frames with 802.1ad VLAN ID 100 in the example above.

-----------------------------[cut here]-----------------------------

Judging from the fact that I received no answer whatsoever, I can only
deduce that offloading an 8021ad bridge, at least one that has the
semantics that Toshiaki Makita described here,
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=1a0b20b257326523ec2a6cb51dd6f26ef179eb84
is not possible with this hardware.

So I think there's little left to do here.

If it helps, I am fairly certain that the sja1105 can offer the
requested services, if you play a little bit with the TPID and TPID2
values. Maybe that's a path forward for your patches, if you still want
to add the generic support in switchdev and in DSA.

Thanks,
-Vladimir