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