Concepts And Terms - H3C S3600V2 SERIES Layer 2-Lan Switching Configuration Manual

Figure 69 Application scenario of two-to-two VLAN mapping
QinQ or selective
QinQ
PE 1
CE a1
Site 1 and Site 2 are in VLAN 2 and VLAN 3, respectively. The VLAN assigned for VPN A is VLAN 10
in the SP 1 network and VLAN 20 in the SP 2 network.
If Site 1 sends a packet to Site 2, the packet is processed on the way to its destination using the following
workflow:
When the packet tagged with VLAN 2 arrives at the edge of network SP 1, PE 1 tags the packet
1.
with outer VLAN 10 through basic QinQ or selective QinQ.
When the double-tagged packet enters the SP 2 network, PE 3 replaces the outer VLAN tag (VLAN
2.
10) with VLAN 20. Because the packet is destined for Site 2 in VLAN 3, PE 3 also replaces the
inner tag (VLAN 2) of the packet with VLAN 3. This process is two-to-two VLAN mapping.
When PE 4 receives the packet with the new VLAN tag pair, it removes the outer VLAN tag and
3.
forwards the packet to VLAN 3.
For more information about basic QinQ and selection QinQ configurations, see

Concepts and terms

Figure 70 shows a simplified network to help explain the concepts and terms that you might encounter
when you work with VLAN mapping.
Figure 70 Basic concepts of VLAN mapping
Uplink traffic—Traffic transmitted from the customer network to the service provider network.
•
VLAN 10 VLAN 2 Data
SP 1
VLAN 2 Data
VPN A
Site 1
Two-to-two VLAN
mapping
PE 2 PE 3
Traffic
204
QinQ or selective
VLAN 20 VLAN 3 Data
SP 2
VLAN 3 Data
VPN A
Site 2
"Configuring
QinQ
PE 4
CE a2
QinQ."