3.1 Configuration Information:
On PE1:
#
Interface GigabitEthernet2/0/16
Undo portswitch
Mpls l2vc 111.111.111.111 90
#
On PE2:
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Interface GigabitEthernet4/0/16
Undo portswitch
Mpls l2vc 90.90.90.90 90
#
3.2 Packets Entering the Tunnel:
1. If the packet sent by CE1 carries a layer of VLAN, as shown in Figure 1, when processing into the tunnel, the V1R2 version is processed as follows:
When the encapsulation mode is Ethernet, the packets in the original packet are stripped and then forwarded to the tunnel. The packets received by PE2 are:
The V1R3 version starts processing differently from V1R2. When entering the tunnel, the VLAN in the original packet is not stripped.
2. If the packet sent by CE1 has two layers of VLANs:
When a packet enters the tunnel, the V1R2 version strips the outer VLAN:
As of V1R3, PE1 encapsulates the two VLANs in the MPLS packets and forwards them to the peer PE2.
3. If the packet sent by CE1 does not carry a VLAN, the packet encapsulates the MPLS header on the original packet and then forwards it to PE2.
3.3 Packet Outbound Tunnel:
When a packet is sent out of the tunnel, regardless of whether the packet received from the peer PE carries the VLAN information of the original packet, the version does not process any packet. The MPLS header is directly stripped and then transparently transmitted to the packet. The local CE, that is, the number of VLANs of the original packets carried in the packets sent by the PE1, is forwarded to the CE2.
3.4 Supplementary notes:
When a packet is sent to the tunnel, the V1R2 and V1R3 versions are not affected. The V1R3 version does not modify the VLAN information of the packet.
The summary of Handling of VLANs in Packets in Various Versions of L2VPN Configurations .http://forum.huawei.com/enterprise/en/forum.php?mod=viewthread&tid=453137
