Operation Manual – VLAN-VPNH3C S5600 Series Ethernet Switches Chapter 2 Selective QinQ Configuration2-2VIPVLAN101~200UserVLAN8 ~100IP PhoneVLAN201~300VLAN 8~300VLAN 1001~1003ServerVLAN8~100VIP ServerVLAN101~200VoIP DeviceVLAN201~300SwitchAPublic NetworkVLAN1001/1002/1003Figure 2-1 Diagram for a selective QinQ implementationIn this implementation, Switch A is an access device of the service provider. The usersconnecting to it include common customers (in VLAN 8 to VLAN 100), VIPs (in VLAN101 to VLAN 200), and IP telephone users (in VLAN 201 to VLAN 300). Packets of allthese users are forwarded by Switch A to the public network.After the selective QinQ feature and the inner-to-outer tag mapping feature are enabledon the port connecting Switch A to these users, the port will add different outer VLANtags to the packets according to their inner VLAN tags. For example, you can configureto add the tag of VLAN 1002 to the packets of IP telephone users in VLAN 201 to VLAN300 and forward the packets to the VoIP device, which is responsible for processing IPtelephone services.To guarantee the quality of voice packet transmission, you can configure QoS policiesin the public network to reserve bandwidth for packets of VLAN 1002 and forward thempreferentially.In this way, you can configure different forwarding policies for data of different type ofusers, thus improving the flexibility of network management. On the other hand,network resources are well utilized, and users of the same type are also isolated bytheir inner VLAN tags. This helps to improve network security.