Operation Manual – QinQ-BPDU TunnelingH3C S5500-EI Series Ethernet Switches Chapter 1 QinQ Configuration1-2Figure 1-1 Single-tagged frame structure vs. double-tagged Ethernet frame structureAdvantages of QinQ:z Addresses the shortage of public VLAN ID resource.z Enables customers to plan their own VLAN IDs, without running into conflicts withpublic network VLAN IDs.z Provides an easy-to-do Layer 2 VPN solution for small-sized MANs or intranets.Note:The QinQ feature requires configurations only on the service provider network, and noton the customer network.1.1.2 Implementations of QinQThere are two types of QinQ implementations: basic QinQ and selective QinQ.1) Basic QinQBasic QinQ is a port-based feature, which is implemented through VLAN VPN.With the VLAN VPN feature enabled on a port, when a frame arrives at the port, theswitch will tag it with the port’s default VLAN tag, regardless of whether the frame istagged or untagged. If the received frame is already tagged, this frame becomes adouble-tagged frame; if it is an untagged frame, it is tagged with the port’s default VLANtag.2) Selective QinQz Selective QinQ is a more flexible, VLAN-based implementation of QinQ. Inaddition to all the functions of basic QinQ, selective QinQ can tag the frame withdifferent outer VLAN tags based on different inner VLAN IDs.
