Users Guide

Layer 2 Protocol Tunneling
Spanning tree bridge protocol data units (BPDUs) use a reserved destination MAC address called the bridge group address,
which is 01-80-C2-00-00-00.
Only spanning-tree bridges on the local area network (LAN) recognize this address and process the BPDU. When you use VLAN
stacking to connect physically separate regions of a network, BPDUs attempting to traverse the intermediate network might be
consumed and later dropped because the intermediate network itself might be using spanning tree (shown in the following
illustration).
Service Provider Bridging 731