Setting this object to enabled or disabled controls, at the switch-wide level, whether bridge control protocol (BPDU) transparency is active, which governs how Layer 2 control frames like spanning-tree BPDUs are handled when crossing the switch. An administrator enables this feature when the switch needs to pass through BPDUs transparently between two customer sites without participating in their spanning tree. For example, enabling zyBridgeControlProtocolTransparencyState lets a service provider switch tunnel a customer's spanning-tree BPDUs across the provider network without the provider's own switch processing them as its own STP traffic.