wfBrSrBaseStpBridgeID 1.3.6.1.4.1.18.3.5.1.1.2.1.33

The Spanning Tree Bridge ID assigned to this bridge. It is a 8-octet string. The first two octets make up the bridge priority, and the last six are the MAC address of this bridge, which is commonly the MAC address of the first port on the bridge.