- OpenFlow is a protocol-implementing Software Defined Networking, a new networking paradigm, which segregates packet forwarding and accounting from the routing decisions and advanced protocols. This segregation increases agility and flexibility and reduces operational expenses of the networking infrastructure. Despite the apparent benefits, many companies are unable to upgrade their networks to OpenFlow unless they renew their supplementary management and security infrastructures as well. The proposed solution, called NetFlow for OpenFlow (NFO) bridges the gap between trusted state-ofthe-art network monitoring infrastructures and standard OpenFlow networks. The proposed Flow Discovery technique enables the highest granularity per-flow monitoring while the Flow Assignment algorithm balances the monitoring resources to avoid overloading of routers. Overall, NFO makes the collection of flow-statistics in OpenFlow environment easier, cheaper, and more accurate.