# A Systematic Literature Review on Military Software Defined Networks
## 4 Identified Significant Research Contributions
### Control Systems
Furthermore, the authors propose the adoption of this method to SDNs, for the enforcement of protection policies (during message forwarding decisions) in accordance with specific node and link attributes. The aforementioned statement is promoted as a suggestion by the authors, while deployment and validation is required. [PERSON] et al. [32] proposed a distributed flow controller for mobile ad hoc networks, seeking to provide dynamic reconfiguration and to improve security. The functions of the controller are (i) provisioning of AAA (authentication, authorization and accounting) services, (ii) flow management across the network nodes, (iii) centralized network traffic control, and (iv) enforcement of security policy. Unicast, multicast and broadcast communication is supported, while suitable mechanisms are provided for the management of topology changes. A core component of the proposed system is the selection mechanism, which establish the number of required controllers and their prioritization. This mechanism is mathematically analyzed, and tested within a test-bed consisting of seven wireless nodes providing positive initial results. The article provides a small scale validation, while further testing is recommended, primarily related to the size of the network and the tested mobility patterns. Furthermore, [PERSON] et al. [55] proposed a set of novel architecture designs for SDN-enabled mobile ad hoc networks in the tactical edge, discussed the challenges raised by the ad hoc and coalition network environment, and presented corresponding solutions. The proposed approaches build on experimental evaluations, utilizing theoretical results from SDN deployments in large backbone networks. The study provides useful insights on the examined environment, yet security related aspects could benefit from further evaluation. [PERSON] et al. [26] described an optimization algorithm that can be used for prioritizing service requests in military operations. According to the article, when a network does not have enough resources to serve all requests, these can be prioritized based on a predefined policy. To enable service prioritization, a set of resources that are required by the service must be prioritized. In the context of SDN, this primarily concerns prioritization of traffic on network devices. The authors suggest precombining these resources into groups, and proposed an algorithm to optimize this precombination. The authors suggested two models of optimization, where the provided results show that precombination of resource dispatching improves the network performance. Furthermore, [PERSON] et al. [33] proposed a DIstributed SDN Control (DISCO) plane which allows handling the distributed and heterogeneous nature of modern mission-critical networks. The proposed approach relies on a per domain organization, where each DISCO controller is in charge of an SDN domain, using a lightweight and manageable publish-subscribe mechanism for sharing aggregated local and network-wide information with neighbor SDN controllers. Furthermore, the authors demonstrate how DISCO dynamically adapts to heterogeneous network topologies, while providing classic functionalities such as end-point migration and being resilient enough to survive disruptions and attacks. The authors implement DISCO on top of Floodlight, an OpenFlow controller, and the Advanced Message Queuing Protocol (AMQP). The network is emulated using Mininet to create topologies and instantiate Open vSwitch switches and virtual hosts. Mininet is hosted on a dedicated VM (Virtual Machine) and the controllers are hosted on separate VMs. To measure performance, the authors show an evaluation of its functionalities on an emulated SDN according to two use cases: (i) inter-domain connectivity disruption and (ii) migration of a virtual machine. The results show how DISCO dynamically adapts to heterogeneous network topologies, while being resilient enough to survive disruptions and attacks, and further being able to provide classic functionalities such as end-point migration.