H3C S5100-SI Operation Manual page 715

# Enable the VLAN-VPN feature on GigabitEthernet 1/0/21 of Switch B and tag the packets received on
this port with the tag of VLAN 1040 as the outer VLAN tag.
<SwitchB> system-view
[SwitchB] vlan 1040
[SwitchB-vlan1040] port GigabitEthernet 1/0/21
[SwitchB-vlan1040] quit
[SwitchB] interface GigabitEthernet 1/0/21
[SwitchB-GigabitEthernet1/0/21] vlan-vpn enable
# Set the global TPID value of Switch B to 0x9200 and configure GigabitEthernet1/0/22 as a VLAN VPN
uplink port, so that Switch B can intercommunicate with devices in the public network.
[SwitchB-GigabitEthernet1/0/21] quit
[SwitchB] vlan-vpn tpid 9200
[SwitchB] interface GigabitEthernet1/0/22
[SwitchB-GigabitEthernet1/0/22] port link-type trunk
[SwitchB-GigabitEthernet1/0/22] port trunk permit vlan 1040
[SwitchB-GigabitEthernet1/0/22] vlan-vpn uplink enable
Do not configure VLAN 1040 as the default VLAN of GigabitEthernet 1/0/12 of Switch A and
GigabitEthernet 1/0/22 of Switch B. Otherwise, the outer VLAN tag of a packet will be removed
during transmission.
In this example, both GigabitEthernet1/0/11 of Switch A and GigabitEthernet1/0/21 of Switch B are
access ports. In cases where the ports are trunk ports or hybrid ports, you need to configure the
two ports to remove the outer VLAN tags before transmitting packets of VLAN 1040. Refer to Port
Basic Configuration in this manual for detailed configuration.
Configure the devices in the public network
# As the devices in the public network are from other vendors, only the basic principles are introduced
here. That is, you need to configure the devices connecting to GigabitEthernet 1/0/12 of Switch A and
GigabitEthernet 1/0/22 of Switch B to permit the corresponding ports to transmit tagged packets of
VLAN 1040.
Data transfer process
The following describes how a packet is forwarded from Switch A to Switch B in this example.
1) As GigabitEthernet 1/0/11 of Switch A is a VLAN-VPN port, when a packet from the customer's
network side reaches this port, it is tagged with the default VLAN tag of the port (VLAN 1040).
2) The switch sets the TPID value for the outer VLAN tags of packets to user-defined value 0x9200
and then forwards these packets to the public networ through the VLAN-VPN uplink port
GigabitEthernet 1/0/12.
3) The outer VLAN tag of the packet remains unchanged while the packet travels in the public network,
till it reaches GigabitEthernet1/0/22 of Switch B.
4) After the packet reaches Switch B, it is forwarded to GigabitEthernet1/0/21 of Switch B. As the port
belongs to VLAN 1040 and is an access port, the outer VLAN tag (the tag of VLAN 1040) of the
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