This Counter64 counts the number of times the transparent firewall flooded a frame out to all egress interfaces because the destination MAC address wasn't found in its bridge table, accumulated since the last reboot. An admin uses it to gauge how often the bridge is falling back to flooding rather than making a direct forwarding decision, which can indicate an incomplete or thrashing MAC address table. A high flood rate on a stable network would prompt an admin to check whether the bridge table is too small or aging out entries too aggressively.