Huawei Quidway S3900 Series Operation Manual page 940

Operation Manual – VLAN VPN
Quidway S3900 Series Ethernet Switches-Release 1510
Note:
The following describes how a packet is forwarded from Switch A to Switch C.
As the Ethernet1/0/1 port of Switch A is a VLAN-VPN port, when a packet from the
user's private network side reaches Ethernet1/0/1 port of Switch A, it is tagged with
the default VLAN tag of the port (VLAN 10) and is then forwarded to Ethernet1/0/2
port.
Because Ethernet1/0/2 port is configured with VLAN-VPN TPID, Switch A changes
the TPID value in the outer VLAN Tag of the packet to 0x9100 and forwards the
packet to the public network.
The packet reaches Ethernet3/1/2 port of Switch B in the public network. Switch B
forwards the packet in VLAN 10 to Ethernet3/1/1.
The packet is forwarded from Ethernet3/1/1 port of Switch B to the network on the
other side and enters Ethernet1/0/2 port of Switch C. Then Switch C forwards the
packet in VLAN 10 to its Ethernet1/0/1. As Ethernet1/0/1 port is an access port,
Switch C strips off the outer VLAN tag of the packet and restores the original packet.
It is the same case when a packet travels from Switch C to Switch A.
After the configuration, the networks connecting Switch A and Switch C can receive
data packets from each other.
Huawei Technologies Proprietary
1-8
Chapter 1 VLAN-VPN Configuration