Compatibility with 802.1Q-2014
It seems that we might not be fully compatible with the definition of VLAN Bridge in 2020-02-19-802.1Q-tagging.txt. The good news is that HDL is pretty-well implemented, it is simply not correctly configured in the software. Some points from reading 802.1Q-2014:
- the default VID for handling untagged and priority-tagged traffic is VID=1
- all received untagged and priority-tagged frames are "internally" tagged with VID=1 and untagged on transmission, unless configured differently.
- One cannot tag with PVID=0, one cannot change configuration of VID=0, it seems there is no VID=0 in the VLAN data base
- by default, only VID=1 is untagged on transmission
- from all the above, it seems that if a priority frame is received on a port, it will surely not be sent out as priority frame (which is strange...) - see page 74, section 6.9.1:
The value of the vlan_identifier parameter is as follows: e) The value contained in the VID field, optionally translated using the VID translation table, if the frame is VLAN-tagged; f) The value of the PVID for the Port, if Port-and-Protocol-based VLAN classification is not supported and the frame is untagged, Priority-tagged, or the VID translation table is supported and the translated VID value (relay VID) is zero; g) As determined by Port-and-Protocol-based VLAN classification (6.12) if that capability is implemented and the frame is untagged or Priority-tagged or the VID translation table is supported and the translated VID value (relay VID) is zero.
- it seems that our "DISABLED" mode of port is illegal: one cannot admit NULL tags, ever
- overriding of priority seems odd as well (I did not understand from the standard that it is possible)