Configuring Qinq; Operation - HP A5830 Configuration Manual

Configuring QinQ

CVLANs, also called inner VLANs, see the VLANs that a customer uses on the private network. SVLANs,
also called outer VLANs, see the VLANs that a service provider uses to carry VLAN tagged traffic for
customers.
QinQ is a flexible, easy-to-implement Layer 2 VPN technology based on IEEE 802.1Q. QinQ enables the
edge device on a service provider network to insert an outer VLAN tag in the Ethernet frames from
customer networks, so that the Ethernet frames travel across the service provider network (public network)
with double VLAN tags. QinQ enables a service provider to use a single SVLAN to serve customers who
have multiple CVLANs.
The IEEE 802.1Q VLAN tag uses 12 bits for VLAN IDs. A device supports a maximum of 4094 VLANs.
This is far from enough for isolating users in actual networks, especially in MANs.
By tagging tagged frames, QinQ expands the available VLAN space from 4094 to 4094 × 4094. QinQ
delivers the following benefits:
Releases the stress on the SVLAN resource.

Enables customers to plan their CVLANs without conflicting with SVLANs.

Provides an easy-to-implement Layer 2 VPN solution for small-sized MANs or intranets.

Enables the customers to keep their VLAN assignment schemes unchanged when the service

provider upgrades the service provider network.

Operation

The devices in the public network forward a frame only according to its outer VLAN tag and obtain its
source MAC address into the MAC address table of the outer VLAN. The inner VLAN tag of the frame is
transmitted as the payload.
Figure 48 Typical QinQ application scenario
VLANs 1 to 20
Customer
network B
PE 1
Customer
network A
VLANs 1 to 10
CE 3
VLAN 4
IP network
VLAN 3
Public network
CE 1
VLANs 1 to 10
CE 4
VLAN 3
VLAN 4
CE 2
VLANs 1 to 20
145
Customer
network A
PE 2
Customer
network B