# Practical Implementation of a Blockchain-Enabled SDN for Large-Scale Infrastructure Networks
## 2 Related Work
Models with both monopolistic ISPs and multiple CPs (Content Providers) and oligopolistic (multiple) ISPs with multiple CPs are considered and studied, in order to predict how this would affect end -users, CPs and ISPs. The complex interaction system between the mentioned players was modeled as a non-cooperative game. Based on the analysis, the differential pricing scheme can be unfair to the CPs with better QoS and can promote the situation in which the CPs with poor QoS receive more traffic, which will downgrade the experience for the end user. The study concludes that CPs with poor QoS should not be able to offer higher sponsorship to ISPs than CPs with better QoS, for the end user to have a similar or better experience. The study in [9] proposes a solution for automating NOC (Network Operations Center) tasks and helping with taking the recommended actions for maintaining the network's health and assuring SLAs (Service Level Agreements). The proposed solution is said to help ISPs balance between offering high QoS to customers in order to meet SLAs and keeping the operational costs at a minimum level. The study used supervised machine learning to train the model used in the solution and obtain automation for selecting the best action, the results in the controlled environment being similar to the ones of expert technicians. Next, articles are presented that use SDN technology in the WAN together with blockchain. The study in [10] proposes a solution to improve SDN security for IoT deployments, using blockchain. The solution proposes three key elements for every IoT deployment: IoT Application Server, SDN network and the secure gateway node introducedby this solution. This node is connected to the sensors and gathers the communication from sensors and redirects it to the SDN network nodes. The secure gateway validates the external traffic. The authenticity of the external traffic is validated using blockchain as the primary distributed encrypted archive which has the up-to-date information. The information here cannot be modified or corrupted, so the authorized nodes can keep track and verify the data generated by the IoT devices by checking the most recent blocks. In [11], a secure distributed SDN architecture is proposed for IoT using blockchain. This architecture is called DistBlockNet and adopts a secure distributed control of the network, using blockchain to improve security, scalability and flexibility without using a centralized controller. In the proposed architecture, the controllers in the IoT network are interconnected in a blockchain network-like manner to facilitate the communication between the IoT forwarding devices. There are three modules used: OrchApp, Controller and Shelter. The network traffic is monitored and filtered by the proposed modules. The architecture assures operational flexibility and incident prevention based on recurrent threats. The study claims that the architecture is agile, modular and safe, adapting dynamically to threats without any intervention from administrators. The distributed blockchain network contains verification nodes and forwarding nodes. The verification nodes ensure that the flow rules in the database are up to date. The forwarding nodes update the flow rules table from the blockchain network. The rule set obtained from a controller is verified by checking if there is synchronization with the other nodes and the rules are not altered and up to date. The work in [12] provides a comprehensive survey of SDN integration with blockchain technologies for IoT networks. It explores the potential benefits and challenges of this integration, named BC-SDIoT, and offers insights into current research and developments in this promising area. Integrating SDN with blockchain offers a feasible solution to cybersecurity challenges in IoT. Paper [13] proposes a system that uses distributed SDN controllers over different network domains for managing the inter-domain SD-WAN (Software-Defined Wide-Area Networks) networks.