QinQ (Double Tagging) for Service Providers Chapter 14RADWIN 2000 User Manual Release 2.6.50 14-2IEEE 802.1Q is used as the encapsulation protocol to implement this mechanism over Ether-net networks.QinQ (Double Tagging) for Service ProvidersQinQ is useful for Service Providers, allowing them to use VLANs internally in their “transportnetwork” while mixing Ethernet traffic from clients that are already VLAN-tagged.Figure 14-2: Separating client data streams using double taggingThe outer tag (representing the Provider VLAN) comes first, followed by the inner tag. InQinQ the EtherType = 0x9100. VLAN tags may be stacked three or more deep.When using this type of “Provider Tagging” you should keep the following in mind:• Under Provider Tagging, the system double-tags egress frames towards the Provider’snetwork. The system adds a tag with a VLAN ID and EtherType = 0x9100 to allframes, as configured by the service provider (Provider VLAN ID).• The system always adds to each frame, tags with VLAN ID and EtherType = 0x9100.Therefore,• For a frame without a tag – the system will add a tag with VLAN ID andEtherType = 0x9100 so the frame will have one tag• For a frame with a VLAN tag – the system will add a tag with VLAN ID andEtherType = 0x9100 so the frame will be double-tagged• For a frame with a VLAN tag and a provider tag – the system will add a tag withVLAN ID and EtherType = 0x9100 so the frame will be triple-tagged and so onVLAN UntaggingVLAN Untagging means the removal of a VLAN or a Provider tag.Port FunctionalityThe VLAN functionality is supported by all LAN and SFP ports in the IDU.Each port can be configured how to handle Ethernet frames at the ingress direction (whereframes enter the IDU) and at the egress direction (where frame exit the IDU).The configuration is independent at each port.
