On Mon, Feb 18, 2019 at 12:07:54PM +0100, Matthias May wrote: > On 15/02/2019 01:28, Ben Pfaff wrote: > > On Fri, Feb 15, 2019 at 12:27:11AM +0100, Matthias May wrote: > >> On 14/02/2019 20:17, Ben Pfaff wrote: > >>> On Thu, Feb 14, 2019 at 10:58:48AM +0100, Matthias May via dev wrote: > >>>> There are switches which allow to transmit their BPDUs VLAN-tagged. > >>>> With this change OVS is able to receive VLAN-tagged BPDUs, but still > >>>> transmits its own BPDUs untagged. > >>>> This was tested against Westermo RFI-207-F4G-T3G. > >>>> > >>>> Signed-off-by: Matthias May <[email protected]> > >>> > >>> Thanks for the patch. > >>> > >>> To me, it seems really odd to treat packets with and without an > >>> arbitrary VLAN header the same way. I could see it if the VLAN header > >>> had VID 0 or 1 or some other specified value, but it seems unusual to > >>> ignore it entirely. Is this standardized or a de facto standard of some > >>> kind? > >>> > >> > >> I totally agree. > >> To me a VLAN header has nothing lost on a BPDU of a (R)STP frame, simply > >> because (R)STP is not per VLAN. > >> > >> However the fact is that there are switches which are transmitting > >> frames on a VLAN. > >> > >> With this change we simply ignore the VLAN header if is present. The > >> meaning of the BPDU doesn't cheange. The provided information still is > >> not per VLAN and applies to all ports the same. > >> > >> This patch does not add the ability to transmit VLAN tagged BPDUs for > >> the same reasoning above: RSTP/STP is not supposed to be per VLAN. > >> I was thinking about adding to the patch that one can specify a VLAN via > >> config and only BPDUs with the configured VLAN are accepted. I guess > >> this is what you propose: only accept vlan tagged BPDUs on a specified > >> VLAN. > >> Having such a config-parameter would also enable to transmit the BPDUs > >> VLAN tagged. But I'm still of the opinion that this only suggests that > >> one could have an (R)STP tree per VLAN. > > > > I see we are basically in agreement, but I'd like more information, if > > you have it. > > > > Do the switches that transmit RSTP on a VLAN transmit it on a particular > > VLAN like 0 or 1? (Maybe they are transmitting them as priority-tagged > > frames for some reason?) If so, then it would be possible to accept > > just that VLAN. > > > > Hi Ben > The switch I tested against has config options to specify with which VLAN the > BPDUs should be transmitted. > From the tests I did, for this switch it doesn't matter if the received BPDUs > are tagged or not. The VLAN header is > simply ignored. > I have an open question with the vendor regarding this. > > I did some digging on the net how other switches handle this. E.g at [1]. > From what I get, switches which allow tagged BPDUs simply ignore the header. > > I started reading the 802.1d-2004 and 802.1q-2018, but so far haven't found > anything which specifies how this situation > should be handled.
I guess networking doesn't always make total sense. It's a shame. I applied the patch to master, thanks! _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
