OpenFlow component - Flow Table

The flow table consists of a set of entries, as shown in the following picture.

• A Match Field, specifying the conditions under which a packet is matched. This can be a combination of incoming port, Ethernet and IPv4 header files, high-layer ports, or metadata
• A Priority Field, set the precedence of the flow entry
• A Counter Field, record statistics of matching packets
• A Instruction Field, specify actions to be performed on matching packet, this field is called Actions
• A Timeouts Field, specify the maximum amount of time or idle time before the entry is expired by the switch
• A Cookie Field, used by the controller to filter flow entries. 
• A Flags Field, alter the way flows are managed. 

It is important to note that the flow table in the switch is not the same thing as the Forwarding Information Base (FIB). A FIB is a simple set of forwarding instructions mapping, at minimum, a destination address to an outgoing port. It supports destination-based switching. An OpenFlow flow table is a sequential set of instructions matching multiple fields, and taking some action based on that match - it supports flow-based switching. 

OpenFlow switch can be either OpenFlow-only or hybrid. A hybrid switch can run under both an SDN controller and the switch vendor's proprietary control plane.