The SDN controllers must be configured as a cluster in active/active or active/passive mode to preserve any information necessary to determine cause of a system failure and to maintain network operations with least disruption to workload processes and flows.

Failure in a known state can address safety or security in accordance with the mission needs of the organization. Failure to a known secure state helps prevent a loss of confidentiality, integrity, or availability in the event of a failure of the SDN controller. Preserving network element state information helps to facilitate continuous network operations minimal or no disruption to mission-essential workload processes and flows.