Configuring a VLAN Tag Termination Sub-interface to Transmit the VPN Service

Virtual private network (VPN) services are classified into L2VPN services and L3VPN services. You can configure VLAN tag termination sub-interfaces on the PEs to connect VPNs to enable the interworking between the CEs and users.

Usage Scenario

Table 1 shows a typical application scenario in which VLAN tag termination sub-interfaces transmit VPN services.

**Table 1** VLAN tag termination sub-interfaces transmitting VPN services
VPN Service	Application
L2VPN	When a VLAN tag termination sub-interface is used to access a L2VPN network, this sub-interface needs to be bound to a Virtual Switching Instance (VSI) or virtual private wire service (VPWS) to enable Layer 2 communication.
L3VPN	When a VLAN tag termination sub-interface is used to access an L3VPN network, this sub-interface needs to be bound to a VPN instance to enable Layer 3 communication.

Pre-configuration Tasks

Before you configure a VLAN tag termination sub-interface to transmit IP services, plan user VLANs so that packets received by the VLAN tag termination sub-interface carry one or two VLAN tags.

Configuring a VLAN Tag Termination Sub-interface: A virtual local area network (VLAN) tag termination sub-interface can be a dot1q VLAN tag termination sub-interface or a QinQ VLAN tag termination sub-interface. In dot1q/QinQ termination, a device identifies whether a packet has one tag or two tags. The device then forwards the packet after stripping one or both tags or discards the packet.

(Optional) Configuring a PW-Tag Action: This section describes how to configure a PW-tag action so that a PE changes the P-Tag of packets to be forwarded over a PW in tagged mode to ensure normal communication with non-Huawei devices on an L2VPN network.

Configuring VPN Services: After you configure the VLAN tag termination sub-interface, you need to configure VPN services so as to enable users to communicate with each over an L2VPN or an L3VPN.

Verifying the VPN Service Configuration on the VLAN Tag Termination Sub-interface: After you configure VPN services on the VLAN tag termination sub-interface, verify the configuration.