[ovs-discuss] RSTP in VLAN

[Matthias May]

On 14/02/2019 16:48, Ben Pfaff wrote:
> On Wed, Feb 13, 2019 at 08:43:56AM +0100, Matthias May via discuss wrote:
>> Hi
>> I've run into the situation where I need to receive/transmit VLAN-tagged RSTP frames.
>>
>> I can not find any information on anyone ever doing that with OVS.
>> Any pointers on how to do that?
>>
>> What I've tried so far:
>> A rule on the bridge in question:
>> ovs-ofctl add-flow br0 "table=0 priority=2000 dl_dst=01:80:c2:00:00:00/ff:ff:ff:ff:ff:ff actions=strip_vlan,NORMAL"
>> I expected at least the receive path to work with this.
>> However in syslog I still get
>> daemon.debug ovs-vswitchd: ovs|00010|rstp_sm(handler20)|DBG|br0, port 1: Bad STP or RSTP BPDU received
>> When a vlan tagged BPDU is received.
> 
> It looks to me like this can only happen if the port has OVS's RSTP
> support enabled on it.  Did you enable RSTP support on the port in
> question?
> 

Hi Ben
Yes RSTP is enabled on the port in question.
I added some debug traces and it seems that the VLAN header is used as
part of the payload.
--> The checks on a valid RSTP/STP frame always fail because the part
where protocol-identifier, version and message type are supposed to be
it's just statically 0x8100.

I'm not sure why it's happening the way it's happening, but it seems the
frame is consumed by the bridge before any rules are applied to it (slow
path?).
I suggest to move this discussion to the thread on the dev-list next to
the proposed patch.

BR
Matthias