Priority Tagged

The VLAN 0 Priority Tagging Support feature enables 802.1Q Ethernet frames to be transmitted with the VLAN ID tag set to zero. These frames are called priority tagged frames. Setting the VLAN ID tag to zero allows the VLAN ID tag to be ignored and the Ethernet frame to be processed according to the priority configured in the 802.1P bits of the 802.1Q Ethernet frame header.

VLAN Default Value and Priority Tagging

The system value L2QVLAN is initially set to “0” and identifies the 802.1Q VLAN Identifier. This default value indicates “priority tagging” as defined in IEEE 802.IQ Section 9.3.2.3. Priority tagging specifies that your network closet Ethernet switch automatically insert the switch port default VLAN without changing the user priority of the frame (cf. IEEE 802.1D and 802.1Q).

The VLAN ID = 0 (zero) is used to associate priority-tagged frames to the port/native VLAN of the ingress port of the switch. But some switches do not understand a VLAN ID of zero and require frames tagged with a non-zero VLAN ID.

If you do not want the default VLAN to be used for voice traffic:

• Ensure that the switch configuration lets frames tagged by the 9600 Series IP Telephone through without overwriting or removing them.
• Set the system value L2QVLAN to the VLAN ID appropriate for your voice LAN.

Another system value you can administer is VLANTEST. VLANTEST defines the number of seconds the 9600 IP Series Telephone waits for a DHCPOFFER message when using a non-zero VLAN ID. The VLANTEST default is “60” seconds. Using VLANTEST ensures that the telephone returns to the default VLAN if an invalid VLAN ID is administered or if the phone moves to a port where the L2QVLAN value is invalid. The default value is long, allowing for the scenario that a major power interruption is causing the phones to restart. Always allow time for network routers, the DHCP servers, etc. to be returned to service. If the telephone restarts for any reason and the VLANTEST time limit expires, the telephone assumes the administered VLAN ID is invalid. The telephone then initiates registration with the default VLAN ID.

Setting VLANTEST to “0” has the special meaning of telling the phone to use a non-zero VLAN indefinitely to attempt DHCP. In other words, the telephone does not return to the default VLAN.

NOTE: If the telephone returns to the default VLAN but must be put back on the L2QVLAN VLAN ID, you must Reset the telephone. See the Reset procedure in the Avaya one-X Deskphone Edition for 9600 Series IP Telephones Installation and Maintenance Guide.