(Optional) Configuring a PW-tag Action

This section describes how to configure a PW-tag action so that a PE changes the P-Tag of packets to be forwarded over a PW in tagged mode to ensure normal communication with non-Huawei devices on an L2VPN network.

Context

On the network shown in Figure 1, CE1 and CE2 are connected to the L2VPN network through PE sub-interfaces, PE1 and CE1 are Huawei devices, and PE2 and CE2 are non-Huawei devices.

When a PE transmits multiple services over one PW, the PE adds different P-Tags to packets of different services to isolate the packets on the L2VPN network. When the packets reach the sub-interfaces of another PE on the other end of the PW, each sub-interface accepts only those packets carrying the same P-Tag as that specified on the sub-interface.

However, because the P-Tags on PE1 and PE2 may be different, PE1 cannot communicate with PE2, and users from user networks connected to CE1 and CE2 cannot communicate with each other.

Figure 1 Networking for accessing an L2VPN through sub-interfaces

To address the problem, configure a PW-tag action on the user-side sub-interface of PE1. The PE1 sub-interface changes the P-Tag of packets to that on PE2 before forwarding the packets over the PW. This allows PE1 to communicate with PE2.

Table 1 provides the default P-Tag values and the P-Tag values after the PW-tag action.

**Table 1** P-Tag values
Sub-Interface Type	Default P-Tag Value	P-Tag Value After the PW-Tag Action
Dot1q sub-interface	VLAN ID in a packet	New VLAN ID
Dot1q VLAN tag termination sub-interface	VLAN ID in a packet
QinQ VLAN tag termination sub-interface	Outer VLAN ID in a packet
QinQ stacking sub-interface	Minimum VLAN ID in the VLAN ID range specified on the sub-interface
QinQ mapping sub-interface	Fixed VLAN ID in the system

Procedure

Run system-view
The system view is displayed.
Run interface interface-type interface-number.subinterface-number
The view of a user-side sub-interface on a PE is displayed.
Run pw-tag { vlan-id | inner-vlan | outer-vlan } [ 8021p { 8021p-value | inner-vlan | outer-vlan } ]
A PW-tag action is configured so that the sub-interface changes the P-Tag of packets before forwarding the packets over the PW in tagged mode.
Run commit
The configuration is committed.