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.

Context

Applications of VLAN tag termination

Inter-VLAN communication
The VLAN technology is widely used because it allows Layer 2 packets of different users to be transmitted separately. With the VLAN technology, a physical LAN is divided into multiple logical broadcast domains (VLANs). Hosts in the same VLAN can communicate with each other at Layer 2, but hosts in different VLANs cannot. The Layer 3 routing technology is required for communication between hosts in different VLANs. The following interfaces can be used to implement inter-VLAN communication:
- Layer 3 Ethernet interfaces on routers
  
  Conventional Layer 3 Ethernet interfaces do not identify VLAN packets. After receiving VLAN packets, they consider the packets invalid and discard them. To implement inter-VLAN communication, create Ethernet sub-interfaces on an Ethernet interface and configure the sub-interfaces to remove tags from VLAN packets.
Communication between devices in the LAN and WAN

Most LAN packets carry VLAN tags. Certain wide area network (WAN) protocols, such as Point-to-Point Protocol (PPP), cannot identify VLAN packets. Before forwarding VLAN packets from a LAN to a WAN, a device needs to record the VLAN information carried in the VLAN packets and then remove the VLAN tags.

When a device receives packets, it adds the locally stored VLAN information to the packets and forwards them to VLAN users.

Procedure

Configure a dot1q VLAN tag termination sub-interface.
1. Run system-view
  
  The system view is displayed.
2. Run interface interface-type interface-number.subinterface-number
  
  The view of an Ethernet sub-interface on the user side of a PE is displayed
3. (Optional) Create a user VLAN group.
  1. Run vlan-group group-id
    
    A user VLAN group is created.
  2. Run group mode { single | multiple }
    
    The working mode of the VLAN group is configured.
    - single: A VLAN group is considered as a user. This means that you cannot collect statistics about QinQ packets or deploy quality of service (QoS) policies based on a VLAN or a VLAN range.
    - multiple: VLANs and VLAN ranges in a VLAN group are considered as different users. This means that you can collect statistics about QinQ packets or deploy QoS policies based on a VLAN or VLAN range to implement refined management.
  3. Run quit
    
    Return to the view of the Ethernet sub-interface on the user side of the PE.
  Configuring a VLAN group allows you to achieve the following purposes:
  - Deploy QoS policies based on services or users so that higher priority service traffic is preferentially forwarded, improving user experience.
  - View statistics about QinQ packets to check whether a device is functioning properly.
4. Run control-vid vid dot1q-termination [ rt-protocol ] or encapsulation dot1q-termination [ rt-protocol ]
  
  The encapsulation type for a VLAN tag termination sub-interface is configured to be dot1q.
  
  Specify rt-protocol so that the dot1q VLAN tag termination sub-interface supports routing protocols.
5. Run either of the following commands:
  - To configure a dot1q VLAN tag termination sub-interface, run the dot1q termination vid low-pe-vid [ to high-pe-vid ] [ vlan-group group-id ] command.
  - To configure a dot1q VLAN tag termination sub-interface and a matching policy for the sub-interface, run the dot1q termination vid low-pe-vid [ to high-pe-vid ] { 8021p { 8021p-value1 [ to val8021p2 ] } &<1-8> | dscp { valdscp1 [ to valdscp2 ] } &<1-10> | eth-type pppoe | default } [ vlan-group group-id ] command.
  - If you do not configure a matching policy, the dot1q VLAN tag termination sub-interface terminates the VLAN tags of packets carrying the specified VLAN ID. If you configure a matching policy, the sub-dot1q VLAN tag termination sub-interface terminates the VLAN tags of packets carrying the specified VLAN ID+802.1p value/DSCP value/EthType.
  - After the dot1q termination vid low-pe-vid [ to high-pe-vid ] [ vlan-group group-id ] command is run in the Ethernet sub-interface view, the specified VLAN range belongs to the sub-interface, and any VLAN ID in the VLAN range cannot be configured together with the 802.1p value/DSCP value/EthType on other sub-interfaces.
6. Run commit
  
  The configuration is committed.
Configure a QinQ VLAN tag termination sub-interface.

The recent version of the NetEngine 8000 F only supports a VLAN group works in single mode on the QinQ VLAN tag termination sub-interface.
1. Run system-view
  
  The system view is displayed.
2. Run interface interface-type interface-number.subinterface-number
  
  The view of an Ethernet sub-interface on the user side of a PE is displayed
3. (Optional) Create a user VLAN group.
  1. Run vlan-group group-id
    
    A user VLAN group is created.
  2. Run group mode { single | multiple }
    
    The working mode of the VLAN group is configured.
    - single: A VLAN group is considered as a user. This means that you cannot collect statistics about QinQ packets or deploy quality of service (QoS) policies based on a VLAN or a VLAN range.
    - multiple: VLANs and VLAN ranges in a VLAN group are considered as different users. This means that you can collect statistics about QinQ packets or deploy QoS policies based on a VLAN or VLAN range to implement refined management.
  3. Run quit
    
    Return to the view of the Ethernet sub-interface on the user side of the PE.
  Configuring a VLAN group allows you to achieve the following purposes:
  - Deploy QoS policies based on services or users so that higher priority service traffic is preferentially forwarded, improving user experience.
  - View statistics about QinQ packets to check whether a device is functioning properly.
4. Run control-vid vid qinq-termination [ local-switch | rt-protocol ] or encapsulation qinq-termination [ local-switch | rt-protocol ]
  
  The encapsulation type for a VLAN tag termination sub-interface is configured to be QinQ.
  - Specify local-switch so that the QinQ VLAN tag termination sub-interface supports local switching.
  - Specify rt-protocol so that the QinQ VLAN tag termination sub-interface supports routing protocols.
5. Run encapsulation qinq-termination [ local-switch | rt-protocol ]
  
  The encapsulation type for a VLAN tag termination sub-interface is configured to be QinQ.
6. Run qinq termination pe-vid pe-vid [ to high-pe-vid ] ce-vid ce-vid [ to high-ce-vid ] [ vlan-group group-id ]
  
  The VLAN tag termination function is configured for the QinQ VLAN tag termination sub-interface.
  
  After you specify rt-protocol, the sub-interface terminates double-tagged packets, and both inner and outer tags must be specific VLAN IDs.
7. Run commit
  
  The configuration is committed.