UMN:CLI User ManualV5812G216If QinQ is configured on the V5812G, it transmits packets adding another Tag to originalTag. Customer A group and customer B group can guarantee security becausetelecommunication is done between each VLANs at Double Tagging part.Double tagging is implemented with another VLAN tag in Ethernet frame header.Preamble Destination Source 802.1Q VLAN Tag Type/Length LLC Data FCSTPID 8100 Priority Canonical 12-bit identifierVLAN Ethernet FramePreamble Destination Source 802.1Q VLAN Tag Type/Length LLC Data FCSVLAN TagTPID 8100/9100 Priority Canonical 12-bit identifier TPID 8100 Priority Canonical 12-bit identifierEthernet Frame using 802.1Q TunnelingFig. 8.4 QinQ FramePort which connected with Service Provider is Uplink port (internal), and which connectedwith customer is Access port (external).Tunnel PortBy tunnel port we mean a LAN port that is configured to offer 802.1Q-tunneling support. Atunnel port is always connected to the end customer, and the input traffic to a tunnel portis always 802.1Q tagged traffic.The different customer VLANs existing in the traffic to a tunnel port shall be preservedwhen the traffic is carried across the networkTrunk PortBy trunk port we mean a LAN port that is configured to operate as an inter-switch link/port,able of carrying double-tagged traffic. A trunk port is always connected to another trunkport on a different switch. Switching shall be performed between trunk ports and tunnelsports and between different trunk ports.8.1.9.1 Double Tagging OperationStep 1 If there is no SPVLAN Tag on received packet, SPVLAN Tag is added.SPVLAN Tag = TPID : Configured TPIDVID : PVID of input portStep 2 If received packet is tagged with CVLAN, the switch transmits it to uplink port changing toSPVLAN + CVLAN. When TPID value of received packet is same with TPID of port, itrecognizes as SPVLAN, and if not as CVLAN.Step 3 If Egress port is Access port (Access port is configured as Untagged), remove SPVLAN. Ifegress port is uplink port, transmit as it is.
