Following the concept of decoupling the application from the network configuration and in concert with the PCP values defined in Table 1, 6.5.3 specifies a default, abstract VLAN interface name and associated VLAN ID value. In deployments intended to use priority-based QoS at the Ethernet layer, this abstract VLAN interface name can be used for ease of use during Connection engineering if the VLAN interface name has not explicitly been adapted. Moreover, the mapping from the abstract VLAN interface name to a concrete VLAN ID can still be adapted prior to connection establishment (see This decoupling allows for any necessary adjustments, e.g., if the default VLAN ID is already in use or deployment-specific requirements demand the use of a different VLAN ID.

Priority-based QoS at the Ethernet layer also relies on the consistent support and configuration of VLANs in the network containing UAFX Stations. Therefore, it is recommended that all Bridge Components (see 6.2) in such networks are configured to forward VLAN-tagged Ethernet frames with the VLAN IDs used by the attached UAFX Station. The overall configuration results in tagged and untagged traffic originating from a UAFX Station.

NOTE: If an End Station Component cannot receive both tagged and untagged frames on the same network interface, VLAN stripping on egress at the connected Bridge Component port or local means, e.g., ignoring the VLAN tag in the network stack, allows reception of frames that were originally sent with a VLAN tag.