H3C Technologies H3C S12500 Series Switches - Manual (Page 205)

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Figure 68 VLAN termination for inter-VLAN communication
LAN-WAN communication
Most packets sent out of LANs carry VLAN tags, but some WAN protocols such as ATM, Frame Relay,
and PPP cannot recognize VLAN-tagged packets. Therefore, before sending VLAN-tagged packets to a
WAN, the sending port must locally record VLAN information and remove VLAN tags from the packets.
VLAN termination can help implement this purpose. You can configure VLAN interfaces to enable
LAN-WAN communication.
As shown in
Figure 69 , the VLANs of the customer network are called customer VLANs (CVLANs), and
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 69 VLAN termination enables LAN-WAN communication
VLAN termination networking solutions
The following QinQ termination networking solutions are available.