H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – QinQ-BPDU Tunneling
H3C S7500E Series Ethernet Switches Chapter 1 QinQ Configuration
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Advantages of QinQ:
z Addresses the shortage of public VLAN ID resource
z Enables customers to plan their own VLAN IDs, with running into conflicts with
public network VLAN IDs.
z Provides an easy-to-do Layer 2 VPN solution for small-sized MANs or intranets.
 Note:
The QinQ feature requires configurations only on the service provider network, and not
on the customer network.
1.1.2 Implementations of QinQ
There are two types of QinQ implementations: basic QinQ and selective QinQ.
1) Basic QinQ
Basic QinQ is a port-based feature, which is implemented through VLAN VPN.
With the VLAN VPN feature enabled on a port, when a frame arrives on the port, the
switch will tag it with the port’s default VLAN tag, regardless of whether the frame is
tagged or untagged. If the received frame is already tagged, this frame becomes a
double-tagged frame; if it is an untagged frame, it is tagged with the port’s default VLAN
tag.
2) Selective QinQ
Selective QinQ is an implementation more flexible than basic QinQ. In addition to all the
functions of basic QinQ, selective QinQ can tag frames with different outer VLAN tags
based on their inner VLAN IDs.
The S7500E series implements selective QinQ by using customer VLAN IDs as match
criteria to classify frames and then tagging the frames that match a certain VLAN ID
with the outer VLAN tag defined in the associated traffic behavior.
1.1.3 Modification of the TPID Value in VLAN Tags
A VLAN tag uses the tag protocol identifier (TPID) field to identify the protocol type of
the tag. The value of this field, as defined in IEEE 802.1Q, is 0x8100.
Figure 1-2 shows the 802.1Q-defined tag structure of an Ethernet frame.