The state of computer network technologies has continually advanced at a rapid pace. Software Defined Networking (SDN) and Blockchain (BC) have emerged as complementary technologies providing support that facilitates greater security and greater network performance for many domains of application, including the Internet of Things (IoT) ecosystem, ideally resulting in an improvement in our collective quality of life. The proliferation of IoT devices, driven by a wide variety of use cases and its ubiquitous availability, combined with the emergence of SDN and BC, presents rich opportunities for various emerging research efforts. This paper presents a comprehensive survey of the studies in which BC and SDN have been integrated into the IoT ecosystem, referred to hereafter as BC-enabled Software- Defined IoT (BC-SDIoT). First, we discuss the motivations and drivers for integrating BC-enabled SDN and BC-SDIoT, as well as the benefits and drawbacks. Second, we categorize the relevant studies according to six key implementation objectives and ideas that combine BC, SDN, and IoT technologies to create smart, secure, and effective frameworks: Security, computing paradigms (edge and fog computing), trust management, access control & authentication, privacy, and networking. In the corresponding sections, we present the categories (i.e., problem domains) of the aforementioned novel taxonomy and discuss related studies (i.e., solutions) in depth. Finally, we outline potential major challenges, open issues, and future prospects that require further research attention and intensive endeavors for complete and ground-breaking frameworks to broaden newer research domains in BC-SDIoT. This survey paper may be a fruitful primer for a reader investigating the exploitation of BC in SDN and IoT ecosystems.

Data flows of various applications, such as video conferencing, telesurgery, online-gaming, etc., require particular treatment regarding Quality of Service (QoS) because of their sensitivity to such parameters as high bandwidth, low delay, and so on. However, provisioning of QoS-based routing services across Autonomous Systems (ASes) poses gruelling challenges due to the distributed nature and business confidentially hesitations. This study presents a novel blockchain-aided QoS-enabled inter-AS routing framework, QoSChain (QC) , by blending merits of Software-Defined Networking (SDN) and Blockchain technologies. QC framework introduces a coordination framework with mutually distrusting participants that eliminates centralized mediators in provisioning QoS among SDN-enabled ASes. Also, QC reduces the time to set up an end-to-end (E2E) path and the number of messages exchanged and processed by SDN controllers for a QoS flow. Furthermore, it alleviates the concerns of network operators regarding potentially sensitive information disclosure resulting from the required information sharing for QoS-based cross-AS paths by masking details of any confidential information. Experimental results verify the feasibility of the proposed framework on E2E QoS-based routing among SDN networks. This work aims at being a useful primer for researchers in providing insights on how blockchain can be deployed in QoS-enabled routing.

Software Defined Networking (SDN) architecture promises to mitigate limitations of traditional networking architectures in order to satisfy today's complex networking needs. However, as all new networking architectures, SDN also presents several inevitable technical challenges to be addressed by researchers. Control plane scalability is one of the crucial issues deserving more attention from both academia and industry in SDN as well. There are many existing solutions proposing a way to alleviate the control plane scalability in SDN. However, one prominent common ground they share is that they measure the control plane scalability performance in terms of typical network QoS parameters such as throughput and latency. Although these metrics may be a good performance indicators for quality of service measurement in mid-term and long-term, they may not reflect real scalability performance of control planes in SDN environments. However, a metric for scalability of control plane in SDN can provide network administrators some insights while they construct their SDN networks. In this paper, we firstly explore the roots of control plane scalability problem in SDN as well as proposed existing solutions. We then propose a metric in order to evaluate the control plane scalability in SDN. We give mathematical models of the proposed metric over different control plane designs. Further, we compare the performance of these control plane designs by extensive experiments.

All new networking architectures come with their own problems. Software Defined Networking (SDN) has its own challenges which are needed to be addressed by researchers as well. One of the crucial problems with SDN is the control plane scalability since it is a bottleneck for its evolution. As the network grows, the number of messages a controller receives also increases. This increase puts the controller scalability in the heart of problems of SDN. In this paper, we propose a hierarchy-based network architecture along with an inter-AS routing approach with QoS. We exploit idea of levels in which networks with controllers reside and a main controller, which works like a broker, is on top of them to keep the global network state and view. Our experiment results indicate that a controller in a hierarchic setting handles 50% less number of traffic than a controller in a non-hierarchic environment.