# A Systematic Literature Review on Military Software Defined Networks
## 2 Related Work  
To the best of the authors' knowledge, no systematic literature review has been conducted earlier on the topic of military SDN. Nevertheless, it must be noted that some of the articles that we encountered, and present in our study, include comprehensive related work sections. In lack of such an earlier study, we have identified a set of stimulating previous surveys and literature reviews, focusing on aspects related to SDN with generic scope, or application domains distinct to the one discussed here. These articles have been utilized as a basis for our study in terms related to research methods, sources, and presentation of results. [PERSON] et al. [1] conducted a systematic literature review on challenges and effects of SDN until June 2014, identifying 44 relevant articles. The authors highlight and discuss topics such as decoupling hardware from software, network management, programmability, and maintenance. Accordingly, they classify the articles in terms related to their contents, as addressing or discussing SDN challenges (6: know-how, 10: demand, 19: implementation), and effects (27: features, 15: management, 10: economic factors). After an extended analysis on these topics, the authors draw related conclusions including that: _\"the analyzed papers mostly describe software defined networking on a very detailed mathematical and technological basis, making it very hard for enterprises and organizations to assess if the technology can have a specific business impact.\"_. [PERSON] et al. [2] provided a literature review on SDN research topics, challenges and solutions, providing a classification of research challenges in SDN, corresponding ongoing research efforts, and a comparison of those. Although this study is not formated as a systematic literature review, it provides a comprehensive overview and discussion of the utilized technologies, methods and open issues, such as load balancing, scalability, and security. Furthermore, [PERSON] et al. [3] provided a survey on SDN at 2015, discussing the latest developments in this research area at that time. The article is not examining in depth specific topics, but it provides a generic and comprehensive overview of SDN theory, but also related research efforts on a wide variety of topics, such as processing optimization, policy and rule validation, network virtualization, and maintenance. [PERSON] et al. [4] conducted a systematic literature review on SDN, seeking to classify research papers published on SDN, investigate existing challenges and opportunities, highlight the evolution of the SDN paradigm, and identify the main contributors in the area. This article has been identified to present the most concrete methodology and presentation of results among the related literature reviews, therefore elements of our methodology (see Section 3) across the undertaken studies for this article have been influenced by its structure. Another well structured and highly influential (605 citations by December 2017) survey on SDN, has been conducted by [PERSON] et al. [5]. As described by the authors _\"This paper offers a comprehensive survey of software-defined networking covering its context, rationale, main concepts, distinctive features, and future challenges.\"_ The authors begin with a comprehensive description of the SDN paradigm discussing elements such as terminology, definitions, the standardization process, and historical overview. Furthermore, they provide a bottom up survey of existing studies across architectural elements such as: programming languages, network applications, interfaces, operating systems, and infrastructure. Finally, this article provides a summary of ongoing research efforts and challenges in eight categories, including resilience and scalability, security and dependability, controller platforms. [PERSON] et al. [6], provided a survey on SDN, focusing on the analysis of the current state of the art and research challenges.