US Patent 7633890 Compatible methods and systems for multiple spanning tree protocols

A compatible method for multiple spanning tree protocols. A verification module is provided between a standard multiple spanning tree (MST) module and a LLC layer and Ethernet driver module. The verification module executes a reception verification procedure and a transmission verification procedure. The verification module, the standard MST module, and the LLC layer and Ethernet driver module are established in a switch. A bridge protocol data unit (BPDU) is received by the verification module. If the BPDU comes from the LLC layer and Ethernet driver module, the verification procedure is executed for the received BPDU. If the BPDU comes from the standard MST module, the transmission verification procedure is executed for the BPDU.