A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> In defence and emergency operations, integration between multiple wireless networks offers the choice of selecting the connection best suited to the type of information transferred, while at the same time expanding the coverage area in regions where only certain networks are available. Without effective command and control systems, response units at the operational edge, where critical real time information is generated and consumed, become “information islands”. Controlling network traffic at higher echelons, in order to make better use of the limited network bandwidth available, improves the situational picture at the control centre and competence of emergency response units on the field. Traffic prioritization, remote network control, and multiple radio integration are three important criteria we are considering in the design of a two-level hierarchical software defined networking architecture for wireless networks, which expand on other SDN properties such as network agility, scalability, and programmability. We have built a prototype with multiple radio interfaces that can provide backhaul for response units by selecting the interface with the highest available throughput, where both policies and configuration can be programmed remotely. Even if our primary use case is geared towards emergency services, military communications challenges share many of the characteristics of emergency operations. <s> BIB001 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> Battlefield networking (BN) considers each network entity as a network in itself, composed of several communication technologies usually interconnected by multiple satellites. In this context, we must consider the intrinsic properties of military contexts to apply SDN in BN to get more flexibility and programmability in network-centric operations. For instance, BN considers several communication technologies, as well as the distinct application requirements on the traffic transmitted over BN in terms of QoS and security features in dynamic environments, where flexible network-centric operations are mandatory. In this article, we define an SDBN architecture that adapts SDN technology to BN, enabling SDNbased applications, methods, and policies. To the best of our knowledge, the proposed architecture in this article is the first one aimed at integrating BN and SDN into dynamic and heterogeneous network-centric environments. <s> BIB002 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> New services put a lot of pressure on the tactical networks, always requiring more bandwidth, service differentiation and agility. In this paper we propose a framework for managing traffic in future tactical networks. Our solution is based on the Mobile Edge Cloud (MEC) architecture and its close interaction with Software Defined Networking (SDN). The whole facilitated by the spread of Software-Defined Radios (SDR) in tactical radios. We have implemented our architecture in a proof of concept and tested it with 2 tactical scenarios. Our experiments show that centralizing the intelligence in the MEC allows to guarantee the requirements of the tactical applications either by adapting the waveform parameters, or through changing the radio interface or even by reconfiguring the applications. More generally, the best decision can be seen as the optimal reaction to the wireless links variations. <s> BIB003 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> Software-Defined Networking (SDN) provides the potential for highly configurable, automated networks by separating the control and forwarding functions of network devices. While SDN appears to have many potential benefits for coalition tactical networking, including rapid reconfigurability and improved network situational awareness, there are significant obstacles to overcome. In particular, the low bandwidth and unreliability that characterize military communication links necessitate a highly resilient control plane, and the exposure of the control plane on the wireless medium presents a new vector for attack. This paper presents the results of a TTCP Workshop on SDN for coalition tactical networking, including an SDN architecture based on protected core networking, a summary of the benefits and challenges, an identification of vulnerabilities, weaknesses and threats and proposals for future work. <s> BIB004 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> The demand for real-time data in a modern battlefield is increasing exponentially. As a result, current military network paradigms and architectures are struggling to cope with increasing capacity demands at the tactical edge. Unfortunately, rescaling existing network architectures will not be a permanent solution to the problem. Therefore, in this paper, we propose a 3- tiered Software Defined Networking (SDN) architecture consisting of heterogeneous Dense Networks (DenseNets), which is a highly condensed deployment of relatively small, lowpowered femtocells, at the tactical edge. The proposed 3-tiered SDN architecture abstracts the Land Tactical Network (LTN) as the Physical Layer, the Battlefield Tactical Network (BTN) as the Control Layer, and the Joint Task Force Headquarters (JTFHQ) as the Management Layer. The simulation and results confirm the architecture’s capability for providing interoperability between heterogeneous communications equipment and supporting high capacity demands within limited and unreliable networking infrastructure in battlefield environments. <s> BIB005 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> Network-centric warfare is a no-way-back trend in modern military operations. The application of this concept ranges from upper-level decision making echelons to troop guidance on the battlefield, and many studies have been carried out in this area. However, most of these are concerned with either the higher-level strategic networks, that is, the networks linking the higher echelons with abundant resources, satellite communications, or even a whole network infrastructure, or high-end TEN, representing resource-rich troops in the field, with military aircraft, battleships, or ground vehicles equipped with powerful wireless communication devices and (almost) unrestricted energy resources for communication. However, these studies fail to take into account the "last-mile TEN," which comprises resource constrained communication devices carried by troopers, equipping sensor nodes deployed in the field or small unmanned aerial vehicles. In an attempt to fill this gap in the studies on battlefield networking, this article seeks to combine software-defined and delay-tolerant approaches to support the diverse range of strict requirements for applications in the last-mile TEN. <s> BIB006 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> The explosive growth in the worldwide use of Unmanned Aerial Vehicles (UAVs) has raised a critical concern with respect to the adequate management of their ad hoc network configuration as required by their mobility management process. As UAVs migrate among ground control stations, associated network services, routing and operational control must also rapidly migrate to ensure a seamless transition. In this paper, we present a novel, lightweight and modular architecture which supports high mobility and situational-awareness through the application of Software Defined Networking (SDN) and Network Function Virtualization (NFV) principles on top of the UAV infrastructure. By combining SDN+NFV programmability we can achieve a robust migration of UAV-related network services, such as network monitoring and anomaly detection as well as smooth UAV migration that confronts high mobility requirements. The proposed container-based monitoring and anomaly detection Network Functions (NFs) as employed within our architecture can be tuned to specific UAV types providing operators better insight during live, high-mobility deployments. We evaluate our architecture against telemetry from over 80 flights from a scientific research UAV infrastructure showing our ability to tune and detect emerging challenges. <s> BIB007 </s> A Systematic Literature Review on Military Software Defined Networks <s> Architectures <s> Real-time systems (RTS) require dependable delay guarantees on delivery of network packets. Traditional approaches for providing such guarantees for mission critical applications require the use of expensive custom built hardware and software resources. We propose a novel framework that reduces the management and integration overheads of the traditional approaches by leveraging the capabilities (especially global visibility and management) of Software-defined networking (SDN) architectures. Given the specifications of flows requiring real-time guarantees, our framework synthesizes paths through the network and associated switch configurations that can meet the requisite delay requirements for real-time flows. Using exhaustive simulations as well as emulations with real switch software, we show the feasibility of our approach. <s> BIB008
A multitude of articles in this category investigate topics related to network monitoring and control. Nobre et al. BIB002 proposed a battlefield networking architecture, enabling the deployment of SDN based applications and policies. The article examines in detail the benefits and disadvantages of (i) centralized, (ii) hierarchical, and (iii) federated approaches, comparing the two later and discussing in detail the supported policy based management solutions. Furthermore, the authors briefly discuss security implications and proceed by examining two use cases related to (i) bidirectional video streaming, and (ii) task coordination. Overall, the article is comprehensive and consistent with current research trends, although further evaluation is suggested. Furthermore, Zacarias et al. BIB006 proposed a joint exploration of the SDN and Delay Tolerant Network (DNT) concepts, in order to address the specific constraints and problems arising at the last-mile Tactical Edge Networking (TEN). The proposed approach takes under consideration the resource constrained devices used by troops in the field, while it benefits from the programmability of SDN, and the ability of DTN to handle link outages. Two use cases are examined in order to highlight the applicability of the proposed architecture. The first sets out a scenario that highlights some of the SDN features within network partitions supporting a non-elastic application. The second use case deals with the management of communication between heterogeneous nodes in the TEN, which spread across different partitions. Mihailescu et al. BIB001 suggested a prototype framework for (i) network control, (ii) traffic prioritization management, and (iii) radio/protocol integration, with the use of SDN for emergency response and military networks. Initially, the article contributes with a two-tier hierarchical SDN controller setup, which exposes a modular interface for the management of wireless networks. Furthermore, the authors proposed a framework that allows the integration and interoperability across distinct wireless network technologies. Both frameworks are presented in detail, related to the desired functionalities of (i) traffic prioritization, (ii) remote network management, and (iii) multiple radio integration. Accordingly, the authors present the results of their initial evaluation process, presenting a small scale prototype implementation. The article investigates an interesting research path, but further evaluation and development is required, since the presented validation approach is small in scale for comprehensively highlighting the overall benefits. Moreover, Phemius et al. BIB003 described an architectural framework for traffic management in tactical networks, combining elements of Mobile Edge Cloud (MED) and SDN, to allow optimal network reactivity to the wireless link variations. The proposed framework can be decomposed into four layers, namely: the (i) "waveform layer" which consists of the multiple deployed programmable radios, the (ii) "SDN layer" which contains a virtual switch and the SDN controller, the (iii) "application management layer" which is mapped to the MED where the applications run, and the (iv) "mobile edge controller" which is a module that bridges the other three layers. Channel state information are periodically measured and aggregated at the controller, which routes the traffic in accordance with these information and dedicated policies deployed within the "mobile edge controller", in order to detect network saturation or bottlenecks and react accordingly. The authors have implemented the proposed architecture in a test-bed that emulates a platoon level tactical network, abstracting the backbone infrastructure, towards the validation of their results. The utilized test-bed is described in detail within the article, while two distinct scenarios are used for validation purposes that primarily relate to network management. Further validation is proposed, given the limited size of the examined topology, but also limitations related to node mobility and communication patterns, which have not been captured extensively under the realistic characteristics of tactical deployments. Nonetheless, the experimentation method is sound and provides viable insights towards future work, which as the authors suggest will include extended configurations. White et al. BIB007 proposed an SND and Network Function Virtualization (NFV) based architecture, within the highly mobile environment of Unamaned Aerial Vehicles (UAV) infrastructures. The proposed architecture aims at (i) improving situational awareness for pilots and payload operators during UAV missions, (ii) increasing continuity of services in deployments with weak backbone infrastructure, (iii) reduction of latency in applications related to situational awareness, and (iv) reduction of the requirements imposed on the backbone infrastructure in cases of outages or traffic spikes. Each UAV is defined as a host, with mobile ground vehicles operating as switches, which route traffic towards the pilots in command and mission payload operators, in accordance with predefined OpenFlow rules. The chained containers hosting the VNFs (Virtual Network Functions) are located in the ground vehicles, while the SDN controller is located at the central command center. The authors implement their architecture with Linux based chained containers for instantiation of the VNFs and the Python SDN controller. Validating their architecture, the authors utilize scenarios that focus on pilot saturation with alerts. The results support an improvement of situational awareness, due to the programmability of reports related to emerging challenges, and an overall improvement in terms of resilience. Furthermore, high mobility patterns are supported through the integrated distributed selection of resilient links with sufficient capacity and availability. Kumar et al. BIB008 describe a framework that leverages the benefits of the SDN paradigm, in order to guarantee end-to-end timing constraints in safety critical Real Time Systems (RTS). The advantage of using SDN in such systems is that it provides a centralized mechanism for developing and managing the system. Furthermore, such a global view is useful in providing the end-to-end delay limitation guarantees that are required. As the authors suggest, another advantage is that the hardware/software resources needed to implement the proposed framework are limited. A prototype is implemented as an application that uses the northbound Application Programming Interface (API) for the controller, which accepts a specification of flows that contain a classification, bandwidth requirements, and the delay constraints of each individual flow. The proposed solution is evaluated using the following two methods: (i) a performance exploration of the path layout algorithm design, and (ii) an empirical evaluation using Mininet, which demonstrate the effectiveness of the end-to-end delay guaranteeing mechanisms. As noted, most hardware switches limit the maximum number of queues that can be allocated to flows, while the presented realization mechanism reserves only one queue per port for each flow, leading to the depletion of available queues. Moreover, Spencer and Willink BIB004 provide a basic evaluation of SDN within coalition networks, and address research challenges related to the dynamic ecosystem of military networks. In particular, the authors focus on dynamic wireless networks and network controller topologies, by presenting the identified challenges and vulnerabilities. The challenges are reflected by the constraints of military networks such as (i) limited bandwidth, (ii) unreliable wireless connectivity, (iii) dependencies of the network controllers, (iv) east-west control plane channels, and (v) data integrity in open networks. Overall, the main contribution of this article, is to present a summary of related challenges identified within the proceedings of a TTCP-C3I (The Technical Cooperation Program-Command, Control, Communications and Information Systems) group. Finally, investigating design and management systems, Elgendi et al. BIB005 propose a three-tiered SDN architecture of heterogeneous and highly dense low-power femtocells at the tactical edge, aiming to satisfy the increasing capacity demands while simplifying the management overhead and increasing scalability. The proposed architecture consists of (i) the physical layer, based on dense low-power femtocells, (ii) the control layer which acts as a local controller, and (iii) a management layer which acts as a global controller. Routing and Quality of Service (QoS) decisions are made at the control layer in coordination with the management layer, the latter also being responsible for handovers. Furthermore, the authors focus on mobility and session management, describing in detail the developed sequential processes and required subsystems. The authors use the Mininet simulator in order to validate their results and evaluate the suggested architecture. The results suggest that within the utilized scenario, the proposed three-tier architecture reduces the delay, while increasing the throughput. Furthermore, the performance of the suggested architecture is evaluated in different mobility scenarios, suggesting that in low speeds a smooth flow rate among femtocells is achievable, while in speeds over 30 km/h the use of hotspots or macrocells is required in order to enhance connectivity. The utilized simulation scenarios are aligned with the high level architectural requirements of tactical networks, although limitations in terms of the deployed number of nodes and mobility models are visible.