The statistics of complete-flush packets received
from this port on specified ring.
Instruction
When the ring recovers, master-node will receive its own
hello packets. It will send complete-flush packets,
instructing the other nodes on the ring to flush their
forwarding database.
When the nodes except master-node receive complete-flush,
they will flush forwarding database. If there is any port
blocked on that node, it will be unblocked.