The C-tag and S-tag components that are added to all VMAN (PBN) frames include C‑ethertype and S-ethertype components that specify an ethertype value for the customer VLAN and VMAN, respectively.
Note
This feature is supported only on the platforms listed for this feature in the license tables in the Switch Engine v33.1.1 Licensing Guide document.The C-tag and S-tag components that are added to all VMAN (PBN) frames include C-ethertype and S-ethertype components that specify an ethertype value for the customer VLAN and VMAN, respectively. The I-tag used in PBBN frames also includes an ethertype value. When a VLAN or VMAN frame passes between two switches, the ethertype is checked for a match. If the ethertype does not match that of the receiving switch, the frame is discarded.
The secondary ethertype support feature applies only to VMANs. The ethertype value for VLAN frames is standard and cannot be changed.
If your VMAN transits a third-party device (in other words, a device other than an Extreme Networks device), you must configure the ethertype value on the Extreme Networks device port to match the ethertype value on the third-party device to which it connects.
The secondary ethertype support feature allows you to define two ethertype values for VMAN frames and select either of the two values for each port.
For example, you can configure ports that connect to other Extreme Networks devices to use the default primary ethertype value, and you can configure ports that connect to other equipment to use the secondary ethertype value, which you can configure to match the requirements of that equipment.
When you create a VMAN, each VMAN port is automatically assigned the primary ethertype value. After you define a secondary ethertype value, you can configure a port to use the secondary ethertype value. If two switch ports in the same VMAN use different ethertype values, the switch substitutes the correct value at each port. For example, for VMAN edge switches and transit switches, the switch translates an ingress ethertype value to the network port ethertype value before forwarding. For egress traffic at VMAN edge switches, no translation is required because the switch removes the S-tag before switching packets to the egress port.
You can set the primary and secondary ethertypes to any value, provided that the two values are different.