# Practical Implementation of a Blockchain-Enabled SDN for Large-Scale Infrastructure Networks
## 6 Discussion  
As the current work is focusing on the practical details concerning the implementation and development of a blockchain-enabled SDN in the context of ISP services validations, the current research is mainly focused on the implementation of a proof of concept for future research endeavors. Future development of this idea may involve exploring custom WAN topologies for controller placement, the utilization of SDN hypervisors to better accommodate dynamic network needs and the integration of already-existing widely used applications for network management.  
In order to accommodate custom WAN topologies, ISPs would need to agree on specific decisions, and certain network developments and configurations might need to be created at the higher infrastructure interconnecting layer. Artificial Intelligence (AI) can be used to help in the deployment and coordination of multiple parties, especially with the federated learning paradigm gaining popularity in recent years. Organizing the ISP network as a decentralized federated learning federation and infusing the blockchain capabilities with AI features would drastically improve the entire system's security and authenticity verifications. The classic federated learning paradigm uses a hierarchy, where an entity has higher privileges, but in the currently proposed ISPs' scenario, a better approach is to organize the WAN SDN controllers in a flat architecture, where each of them has the same privilege.  
Modern networking brings dynamic network function programmability to an existing network. An approach to further enhance network functionality is to enhance the NFV by using network hypervisors, more precisely deploying hypervisor solutions on generic hardware devices, and allowing the hypervisors to activate and deactivate different virtual machines that enable different services that are useful in the entire federation. The CoVisor hypervisor is presented in [27], and it allows multiple SDN controllers to be run concur  
Figure 9: Packet sizes during communication between two SDN blockchain nodes.  
rently on the same computer, sharing their best features to optimize network functions. In the proposed ISP use case, the main ISP controller may employ various solutions for the different services that it agrees to participate in, and in this case, CoVisor would be an ideal enabler tool. Ref. [28] presents the Libera network hypervisor, which can create a dedicated network infrastructure for handling specific network traffic and could be used in conjunction with CoVisor by an ISP to accommodate different network policies and changing internal networks. Such hypervisor solutions are deployed in the middle layers of the network, which in this case would be an advantage for dynamic real-time network functions programmability and configurations.  
Major ISPs already use and reconfigure a large segment of their own networks using tools such as Network Cloud by DriveNets and Apstra by Juniper Networks, to name only a few. These applications, in summary, make the network behave like a cloud where various services can be enabled on various middle devices to avoid congestion and improve network functions. A new paradigm that is an evolution of modern networking is intent-based networking, which is integrated into the aforementioned technologies. These solutions are created to operate only at the internal ISP's network; however, similar solutions can be developed to help organize the upper infrastructure layer between the ISPs, where, with the help of an AI-based federated learning approach, certain features could be requested (or favored) from certain ISPs.