This value, carried in a trap, is a numeric code indicating why an OpenFlow instance's connection to its controller was dropped, such as echo timeout, hello failure, or VRF deletion. An admin cares because it lets the admin immediately diagnose the cause of a controller disconnect without manual investigation, speeding up SDN troubleshooting. For example, a value of 2 in the trap means the connection dropped due to an echo timeout, while 8 would indicate the VRF's global port went down.