ic SDN App Logic Contracts SDN App Logic NBI Driver' NBI Driver' NBI Driver' SDN Northbound Interfaces (NBIs) SDN Controller NBI Agent SDN Control Logic Configure Police CDPI Driver Monitor Performance SDN Control-Data-P Interface (CDPI) Network Element Network Element SDN Datapath* SDN Datapath CDPI Agent CDPI Agent Forwarding Engine / Forwarding Engine / Element Processing Function* Processing Function* Setup Downloaded 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 The Heart and Brain of SDN Criteria to Evaluate a Controller Here comes the most significant portion of the chapter. What are the factors that are taken into account when we need to evaluate a controller? Consider this analogy; you go to an electrical shop to buy a Television. Now when you decide to buy a television, the shopkeeper asks which all remote controllers you want. He shows you three different types. As a normal person you would choose the remote of the same company of which you bought the television of. Right? So, when any organization which sets out to invest, looks for a set of features in its products. The same is the case for SDN Controllers. It might be a little lengthy but read along, it is highly significant if you are inclined towards making a career in SDN. According to the research by Ashton and Metzler (2012) the following are the major 10 salient features or let's just say 10 characteristics that a Controller must have to be identified as a "Usable/Implementable Controller". Network Virtualization This stands to be the most crucial aspect of SDN. It is not a part of SDN though; it is a separate technology which focuses on converting every deployment of network products remotely rather than installing them by hand-on. It is nothing new that came along, it has been there for a long time. VLANs (Virtual Lans) have been in production networks for decades. Another type of network virtualization is VRF. VRF is a network layer protocol where there is presence of physical routers running on their own protoc