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WAN, the sending port must record and remove the VLAN information of the packets. VLAN interfaces
or Layer 3 Ethernet subinterfaces can be used for LAN-WAN communication.
As shown in
the VLANs of the service provider network are called service provider VLANs (SVLANs). When a packet
carrying a CVLAN tag enters the service provider network, it is tagged with a SVLAN tag, and
forwarded based on the SVLAN tag. When the packet is to be forwarded to an external WAN, the
gateway (Device) must perform VLAN termination for the packet and remove the two layers of VLAN tags
from the packet before sending the packet to the WAN.
Figure 46 VLAN termination enables LAN-WAN communication
L2 Switch A
Add a CVLAN tag
VLAN termination configuration task list
Complete the following tasks to configure VLAN termination:
Task
Configuring TPID for VLAN-tagged packets
Enabling a QinQ termination-enabled interface/subinterface to transmit
broadcast and multicast packets
Configuring QinQ termination
Configuring TPID for VLAN-tagged packets
IEEE 802.1Q inserts a four-byte VLAN tag field between the DA&SA field and the type field to carry
VLAN-related information in an Ethernet frame header.
field in Ethernet II encapsulation. Other Ethernet encapsulation formats include 802.2 LLC, 802.2 SNAP,
and 802.3 raw.
Figure 47 Subfields in the VLAN Tag field
Figure
46, the VLANs of the customer network are called customer VLANs (CVLANs), and
L2 Switch B
Enable QinQ, and
add a SVLAN tag
Layer 2 network
Figure 48
compares the structure of a Dot1q packet and that of a QinQ packet.
Device
Packets
Create a Layer 3 Ethernet
subinterface or VLAN
interface to perform QinQ
termination
Figure 47
shows the subfields in the VLAN tag
121
WAN
Remarks
Optional
Optional
Required
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