Configuring Basic QinQ 135
Figure 40 VLAN Tag structure of an Ethernet frame
The device determines whether a received frame carries a service provider VLAN
tag or a customer VLAN tag by checking the corresponding TPID value. Upon
receiving a frame, the device compares the compares the configured TPID value
with the value of the TPID field in the frame. If the two match, the frame carries
the corresponding VLAN tag. For example, if a frame carries VLAN tags with the
TPID values of 0x9100 and 0x8100 respectively while the configured TPID value of
the service provider VLAN tag is 0x9100 and that of the VLAN tag for a customer
network is 0x8200, the device considers that the frame carries only the service
provider VLAN tag but not the customer VLAN tag.
In addition, the systems of different vendors may set the TPID of the outer VLAN
tag of QinQ frames to different values. For compatibility with these systems, you
can modify the TPID value so that the QinQ frames, when sent to the public
network, carry the TPID value identical to the value of a particular vendor to allow
interoperability with the devices of that vendor.
The TPID in an Ethernet frame has the same position with the protocol type field in
a frame without a VLAN tag. To avoid problems in packet forwarding and handling
in the network, you cannot set the TPID value to any of the values in the table
below.
Configuring Basic
QinQ
Follow these steps to configure basic QinQ:
Table 28 Reserved protocol type values
Protocol type Value
ARP 0x0806
PUP 0x0200
RARP 0x8035
IP 0x0800
IPv6 0x86DD
PPPoE 0x8863/0x8864
MPLS 0x8847/0x8848
IPX/SPX 0x8137
IS-IS 0x8000
LACP 0x8809
802.1x 0x888E
Cluster 0x88A7
Reserved 0xFFFD/0xFFFE/0xFFFF
User Priority CFI
DA SA VLAN Tag Etype DATA FCS
TPID VLAN ID
6 bytes 6 bytes 4 bytes
2 bytes 3bits 1 bit 12 bits
4bytes2 bytes 46 to 1500 bytes
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