R0106-HP MSR Router Series Layer 2 - LAN Switching Configuration Guide(V7)

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The devices in the service provider network forward a tagged frame according to its SVLAN tag only. The
CVLAN tag is transmitted as part of the frame's payload.
Figure 30 Typical QinQ application scenario
As shown in Figure 30, customer network A has CVLANs 1 through 10. Customer network B has
CVLANs 1 through 20. The service provider assigns SVLANs 3 and 4 to customer networks A and B,
respectively.
1. When a tagged Ethernet frame from customer network A arrives at PE1, the PE tags the frame with
SVLAN 3. When a tagged Ethernet frame from customer network B arrives at PE1, the PE tags the
frame with SVLAN 4.
2. The double-tagged Ethernet frame is then transmitted over the service provider network and arrives
at the other PE. The PE removes the SVLAN tag of the frame before sending it to the target CE.
QinQ implementations
QinQ is enabled on a per-port basis. The link type of a QinQ-enabled port can be access, hybrid, or
trunk. The QinQ tagging behaviors are the same across these types of ports.
A QinQ-enabled port tags all incoming frames (tagged or untagged) with the PVID tag.
• If an incoming frame already has one tag, it becomes a double-tagged frame.
• If the frame does not have any 802.1Q tags, it becomes a frame tagged with the PVID.
Protocols and standards
• IEEE 802.1Q, IEEE Standard for Local and Metropolitan Area Networks-Virtual Bridged Local Area
Networks
• IEEE 802.1ad, IEEE Standard for Local and Metropolitan Area Networks-Virtual Bridged Local Area
Networks-Amendment 4: Provider Bridges
PE 1
Service provider network
Internet
PE 2
Data flow
VLANs 1 to 20
Customer
network B
CE 3
Customer
network A
VLANs 1 to 10
CE 1
VLANs 1 to 10
Customer
network A
CE 4
VLANs 1 to 20
Customer
network B
CE 2
DataSVLAN 4 CVLAN B
DataSVLAN 3 CVLAN A DataSVLAN 4 CVLAN B
DataSVLAN 3 CVLAN A
DataCVLAN B
DataCVLAN BDataCVLAN A
DataCVLAN A