Layer 2 protocol packets are transparently transmitted based on the following principles:
On the ingress PE of the ISP network, the destination multicast MAC address of a Layer 2 protocol packet is replaced with a specified multicast MAC address.
The devices on the ISP network determine whether to add an outer VLAN tag to the protocol packet according to the configured transparent transmission mode.
When the Layer 2 protocol packet reaches the egress, the destination multicast MAC address of the Layer 2 protocol packet is restored to the standard destination multicast MAC address according to the mapping between the specific destination multicast MAC address configured on the device and the Layer 2 protocol. In addition, the egress determines whether to remove the outer VLAN tag according to the configured transparent transmission mode, and then forwards the protocol packet to the UPE.
The Huawei devices support the following transparent transmission modes of Layer 2 protocol packets in different application scenarios:
Interface-based transparent transmission of Layer 2 protocol packets
VLAN-based transparent transmission of Layer 2 protocol packets
QinQ-based transparent transmission of Layer 2 protocol packets
In future posts we will take a closer look at the transparent transmission modes of Layer 2 protocol packets of Huawei devices.
