Implementation Of Qinq; Adjusting Tpid Values Of Qinq Packets - H3C S9500 Series Operating Manual

Operation Manual – QinQ
H3C S9500 Series Routing Switches
small-sized metropolitan area networks (MANs) or intranets with Layer 3 switches
operate as the core layer devices.
QinQ provides you with the following benefits:
Saves public network VLAN IDs.
You can have VLAN IDs of your own, which do not conflict with public network
VLAN IDs.
Provide simple Layer 2 VPN solutions for small-sized MANs or intranets.

1.1.2 Implementation of QinQ

QinQ can be implemented on S9500 series switches in the following ways:
1) Enabling VLAN VPN on ports
With VLAN VPN enabled, a received packet is tagged with the default VLAN tag of the
port no matter whether or not the packet carries a VLAN tag. Otherwise, the packet is
transmitted with the default VLAN tag carried.
2) Configuring traffic classification-based nested VLANs
Traffic classification-based nested VLANs is also called flexible QinQ. It is a kind of
QinQ implemented in a more flexible way. You can specify to perform the following
operations on packets that match specified ACL rules:
Setting the outer VLAN tags
Modifying the outer VLAN tags

1.1.3 Adjusting TPID Values of QinQ Packets

Tag protocol identifier (TPID) is a portion of the VLAN tag field. IEEE 802.1Q specifies
the value of TPID to be 0x8100.
The structure of the Tag field of an Ethernet frame defined by IEEE 802.1Q is as
follows:
Figure 1-2 The structure of the VLAN Tag field of an Ethernet frame
By default, a S9500 series switch uses 0x8100 as the value of the TPID field, which is
defined by IEEE 802.1Q. But S9500 series switches can also adjust the TPID values of
QinQ packets. This ensures S9500 series switches are compatible with devices coming
from other vendors even through the later use other TPID values (such as 0x9100 or
0x9200) in the outer tags of QinQ packets.
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Chapter 1 QinQ Configuration