the acceptable action on the deployed piece of apparatus (Wilkins, 2014). FLOW TABLES Flow tables area unit the basic knowledge structures in associate degree SDN device. These flow tables allow the device to estimate inward certain packets and take the appropriate action supported the contents of the packet that has simply been established. Packets have sometimes been received by networking devices and evaluated supported sure fields. These actions might absorb forwarding the packet to a precise port, dropping the packet, or flooding the packet on all ports, within the middle of others. Associate degree SDN device isn't essentially completely different except that this basic operation has been rendered additional general and additional programmable through the flow tables and their associated logic. Flow tables comprises variety of prioritized flow entries, every of that characteristically consists of 2 mechanisms: match fields and actions. Match fields area unit accustomed assess against inward certain packets. Associate degree inward certain packet is compared against the match fields in priority order, and also the 1st whole match is chosen. Actions area unit the commands that the network device ought to perform if associate degree inward certain packet matches the match fields specific for that flow entry. Match fields will have wildcards for fields that aren't applicable to a specific match. As an example, once corresponding packets based mostly simply on science address or subnet, all different fields would be wild carded. Similarly, if corresponding on solely waterproof address or UDP/TCP port, the opposite fields area unit unsuitable, and consequently those fields area unit wild carded. Betting on the appliance necessities, all fields are also vital, within which case there would be no wildcards. The flow table and flow entry constructs allow the SDN application developer to own a good vary of potentialities for corresponding packets and taking appropriate actions. (How SDN Works, n.d.) Downloaded: 4/15/