Survey of Promising Technologies for 5G Networks <s> Infrastructure Layer. <s> A flexible and programmable forwarding plane is essential to maximize the value of Software-Defined Networks (SDN). In this paper, we propose Protocol-Oblivious Forwarding (POF) as a key enabler for highly flexible and programmable SDN. Our goal is to remove any dependency on protocol-specific configurations on the forwarding elements and enhance the data-path with new stateful instructions to support genuine software defined networking behavior. A generic flow instruction set (FIS) is defined to fulfill this purpose. POF helps to lower network cost by using commodity forwarding elements and to create new value by enabling numerous innovative network services. We built both hardware-based and open source software-based prototypes to demonstrate the feasibility and advantages of POF. We report the preliminary evaluation results and the insights we learnt from the experiments. POF is future-proof and expressive. We believe it represents a promising direction to evolve the OpenFlow protocol and the future SDN forwarding elements. <s> BIB001 </s> Survey of Promising Technologies for 5G Networks <s> Infrastructure Layer. <s> Software Defined Networking envisions smart centralized controllers governing the forwarding behavior of dumb low-cost switches. But are "dumb" switches an actual strategic choice, or (at least to some extent) are they a consequence of the lack of viable alternatives to OpenFlow as programmatic data plane forwarding interface? Indeed, some level of (programmable) control logic in the switches might be beneficial to offload logically centralized controllers (de facto complex distributed systems) from decisions just based on local states (versus network-wide knowledge), which could be handled at wire speed inside the device itself. Also, it would reduce the amount of flow processing tasks currently delegated to specialized middleboxes. The underlying challenge is: can we devise a stateful data plane programming abstraction (versus the stateless OpenFlow match/action table) which still entails high performance and remains consistent with the vendors' preference for closed platforms? We posit that a promising answer revolves around the usage of extended finite state machines, as an extension (super-set) of the OpenFlow match/action abstraction. We concretely turn our proposed abstraction into an actual table-based API, and, perhaps surprisingly, we show how it can be supported by (mostly) reusing core primitives already implemented in OpenFlow devices. <s> BIB002 </s> Survey of Promising Technologies for 5G Networks <s> Infrastructure Layer. <s> OpenFlow is catalyzing the deployment of software defined networking (SDN) technologies around the globe. In practice, however, compatibility issues hinder the deployment of an OpenFlow control plane on a number of network platforms. The FP7 ALIEN project addresses this problem by introducing a Hardware Abstraction Layer (HAL) which enables OpenFlow capabilities on legacy network elements. This paper presents the implementation of a HAL on programmable network platforms with multi-core CPUs and summarizes the implementation experience gained in the process. <s> BIB003 </s> Survey of Promising Technologies for 5G Networks <s> Infrastructure Layer. <s> This paper describes an experimentally-tested approach towards programmability for legacy network elements in the software-defined networking architecture. As OpenFlow is a leading control-plane protocol enabling SDN in modern networks, yet not all equipment is compatible with this framework. This problem is addressed in ALIEN, the FP7 research project, where Hardware Abstraction Layer (HAL) for non-OpenFlow capable devices is introduced. This paper describes outcomes of the project, and specifically, gives a set of examples of the successful implementation of OpenFlow through the HAL on 'alien' devices. <s> BIB004
The underlying infrastructure layer in SDN consists of switching devices that are interconnected to communicate in a single physical network. In SDN, these forwarding devices are generally represented as basic forwarding hardware or device. These devices are connected wirelessly, using optical fibers, optical wires, cloud networks, and so forth. They maintain connection with the controller through an open interface known as the southbound interface. In most SDNs, OpenFlow is used as the open southbound interface. OpenFlow is a flow-oriented protocol and has switches and port abstraction for flow control. OpenFlow. The OpenFlow protocol maintained by ONF  is a fundamental element for developing SDN solutions and can be treated as an encouraging consideration of any networking abstraction. OpenFlow, the first leading authorized communications interface linking the forwarding and controls layers of the SDN architecture, allows manipulation and control of the forwarding plane of network devices (e.g., switches and routers) both physically and virtually. OpenFlow helps SDN architecture to adapt to the highbandwidth, dynamic nature of user applications, adjust the network to different business needs, and interestingly reduce management and maintenance complexity. Figure 4(a) shows the model of the OpenFlow protocol whereas the algorithm is shown in Figure 4 (b). When a new flow or packet reaches, some lookup manner originates in the primary lookup table and concludes either with a match in the flow tables or with an error depending on the rules specified by the controller. When the packets do not acknowledge what to do with a distinct incoming packet, default information to forward the packet to the controller is "send to controller" in the case of any unmatched entry. If a link or port change is triggered, event-based messages are sent by forwarding devices to the controller. Once the rules are matched with the flow rules, the rule's counter is incremented and actions based on the set rules start getting executed. This could lead to forwarding of a packet, after modifying some of its header fields to a specific port or (i) dropping of the packet and (ii) reporting of the packet back to the controller. The summary some of the most significant characteristics of the data plane  . However, OpenFlow is not the only available southbound interface for SDNs. There are other API proposals such as Forwarding and Control Element Separation (ForCES)  ; Open vSwitch Database (OVSDB)  ; Protocol-oblivious Forwarding (POF) BIB001  ; OpFlex  ; OpenState BIB002 ; Revised OpenFlow Library (ROFL) BIB003 ; Hardware Abstraction Layer (HAL)  BIB004 ; and Programmable Abstraction of Data path (PAD)  .