Flow tables contain rules that tell the switch how to handle packets. Each rule matches on packet headers and specifies an action.
Match fields include: Ingress port, Ethernet MAC addresses, VLAN ID, IP addresses, IP protocol, TCP/UDP ports.
Actions include: Forward to port, drop, send to controller, modify headers, push/pop VLAN tags.
Rule example:
Match: TCP destination port , destination IP
Action: Forward to port
Rules have priorities. Higher priority rules match first.