Configuring Layer 2 Protocol Tunneling (By Replacing Multicast Destination MAC Address)

Some Layer 2 protocols running between user networks, such as Multiple Spanning Tree Protocol (MSTP) and Link Aggregation Control Protocol (LACP), must traverse a backbone network to perform Layer 2 protocol calculation. Therefore, Layer 2 protocol tunneling must be configured.

Usage Scenario

To allow Layer 2 PDUs from user networks to be transparently transmitted over a backbone network, configure Layer 2 protocol tunneling. Layer 2 PDUs from the user networks then travel through different Layer 2 tunnels to reach the destinations to perform Layer 2 protocol calculation.

Pre-configuration Tasks

Before configuring Layer 2 protocol tunneling, complete the following tasks:

Connect the interfaces properly.
Configure the interface type based on whether tagged packets are received.

Configuring an Edge Device to Replace the Multicast Destination MAC Address: To prevent a backbone network edge device from sending the received Layer 2 protocol data units (PDUs) to its CPU for processing and ensure that the Layer 2 PDUs are tunneled across the backbone network, configure the edge device to replace the multicast destination MAC address in Layer 2 PDUs with a specified multicast MAC address.

Enabling Layer 2 Protocol Tunneling on an Interface: If you want backbone network devices to transparently transmit Layer 2 PDUs from user networks, enable Layer 2 protocol tunneling on the device interfaces.

Verifying the Configuration of Interface-based Layer 2 Protocol Tunneling: After configuring interface-based Layer 2 protocol tunneling, check Layer 2 protocol tunneling information, such as the tunneled Layer 2 protocol names, protocol types, multicast destination MAC addresses, and specified multicast MAC addresses (group MAC addresses).