Record the block reason of the port.
notBlock (1) means that the port is not in block state,.
blockForProtocol (2) means that the port is blocked by stp protocol to avoid loop.
blockForRootGuard(3) means that the root guard flag of bridge is set and a better message received from the port,and the port is blocked.
blockForBPDUGuard(4) means that the port has been configured as an edge port and receive a BPDU and thus blocked.
blockForLoopGuard(5) means that the port is blocked for loopguarded.