1. A method of pro-active protection of packet-optical transport in a software defined network (SDN) controller, the method comprising: defining, by the SDN controller, a proactive protection threshold criterion based on based on a plurality of optical system performance metrics; collecting, by the SDN controller, at least one measurement for each of the plurality of optical system performance metrics; determining, by the SDN controller, whether the proactive protection threshold criterion is met based on at least one of the collected measurements; selecting, by the SDN controller, a protection mechanism and defining a protection threshold criterion on a condition that the proactive protection threshold criterion is met; initiating, by the SDN controller, one or more proactive protection events based on the selected protection mechanism; determining, by the SDN controller, whether the protection threshold criterion is met; and implementing, by the SDN controller, one or more protection events on a condition that the protection threshold criterion is met.