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 <matthias....@neratec.com> >>> >>> 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. BR Matthias [1] https://community.extremenetworks.com/extremeswitching-eos-230140/what-happens-if-an-s-series-receives-tagged-rstp-bpdus-7765211 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev