The switch determines whether a received frame carries a VLAN tag by checking the TPID value. For
example, if a frame carries a VLAN tag with TPID value 0x8100, but the configured TPID value is 0x9100,
the switch considers that the frame does not carry any VLAN tag.
The systems of different vendors might set the TPID of the outer VLAN tag of QinQ frames to different
values. For compatibility with these systems, 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, allowing
interoperability with the switches of that vendor.
The TPID in an Ethernet frame has the same position as the protocol type field in a frame without a VLAN
tag. To avoid problems in packet forwarding and handling in the network, do not set the TPID value to
any of the reserved values.
Table 20
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
Protocols and standards
IEEE 802.1Q:
IEEE standard for local and metropolitan area networks: Virtual Bridged Local Area
Networks
QinQ configuration task list
Complete the follows tasks to configure QinQ:
Task
Remarks
Required
Configuring selective QinQ (available only on the A3100 v2 EI)
Optional
Configuring the TPID value in VLAN tags
Optional
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