The SDN (Software-Defined Networking) area evolves rapidly and encompasses a wide area for exploration.To figure out the area which needs sufficient investigation, it is important to consider the research gaps and novel problems. Based on major research issues and detected gaps, we provide a detailed outline on SDN:

Main Research Issues

1. Scalability

• Research Problems: As the network size expands, the centralized form of SDN controllers can become a significant barrier.
• Difficulties:
• While the number of switches extends, the resource usage of controllers also expands.
• In extensive distributed networks, occurrence of time delays.
• Among several controllers, load balancing might be difficult.
• Potential Research Gaps:
• Regarding the multi-controller platforms, state synchronization and distributed decision-making techniques must be processed in an effective manner.

2. Network Security

• Research Problems: SDN networks are vulnerable to novel security attacks due to the centralization and scripting.
• Difficulties:
• Control Plane Security:
• Controllers are influenced by DDoS assaults.
• There is a necessity of verification and approval of API requests.
• Data Plane Security:
• Impaired switches and switch spoofing is one of the main concerns.
• Manipulation of harmful flow rule.
• Potential Research Gaps:
• For the management purpose and data planes, it is crucial to create lightweight and effective intrusion detection techniques.
• Considering the SDN components, integrity and particularity is very essential.

3. Fault Tolerance and Reliability

• Research Problems: Overall network is interrupted due to the breakdown of SDN controller or communication links.
• Difficulties:
• It results in considerable network suspension time because of network breakdown.
• Rapid regeneration and rerouting is efficiently needed for link and switch breakdowns.
• Potential Research Gaps:
• To improve fault resilience, dynamic control placement could be beneficial.
• Effective failure identification and rapid routing techniques needs to be implemented.

4. Quality of Service (QoS) and Traffic Engineering

• Research Problems: Across various traffic groups, it is significant to assure the persistence of QoS and routing traffic dynamically.
• Difficulties:
• Expenses of controller processing are expanded, as the effective flow rule installation rises.
• Path selection and actual-time traffic prioritization might be complex.
• Potential Research Gaps:
• Specifically for dynamic QoS management, implement machine learning-based traffic classification techniques.
• In order to prevent table overflows, flow table management techniques are very important.

5. Network Slicing and Virtualization

• Research Problems: The distributions of physical networks into several virtual networks are included in the network slicing process.
• Difficulties:
• Among slices, it could be difficult for resource utilization and separation.
• Impactful and effective regeneration of network slices are required.
• Potential Research Gaps:
• For network slicing, execute actual-time observation and efficient resource distribution techniques.
• On the basis of multi-tenant SDN networks, it demands productive SLA (Service-Level Agreement) implementation.

6. Multi-Domain and Heterogeneous Networks

• Research Problems: Considering the diverse mechanisms and protocols, synthesization of numerous network fields could be complicated.
• Difficulties:
• Coordinating with various protocols and management models could be a significant issue.
• It requires cross-domain routing and policy implementation.
• Potential Research Gaps:
• As regards multi-domain orchestration, regulated southbound and northbound APIs should be utilized.
• Beyond fields, implement the effective techniques for policy transcription and application.

7. Controller-Switch Communication Protocols

• Research Problems: OpenFlow might not include all application scenarios, even though it is the ideal and original protocol for the SDN network.
• Difficulties:
• Across versions, it results in emergence of issues such as OpenFlow scalability and compatibility.
• It can be difficult to handle hybrid network protocols.
• Potential Research Gaps:
• Novel southbound protocols such as gRPC and P4Runtime must be created and assessed.
• For specific network platforms, design a portable and extensible protocol.

8. Programmable Data Planes

• Research Problems: It exhibits issues, even though programmable switches like P4 offer close-grained control.
• Difficulties:
• While keeping up with high performance, dynamic packet processing is very essential.
• Among current protocols and diverse P4 targets, compatibility is considered as the main problem.
• Potential Research Gaps:
• Superior abstractions are needed for programmable data plane scripting.
• Particularly for several hardware targets, regular and flexible models are critically important.

9. Energy Efficiency

• Research Problems: In extensive-scale networks, expansion of energy usage is a key concern.
• Difficulties:
• While decreasing the energy usage, network performance required to be maintained.
• The energy usage of SDN switches and controllers must be improved.
• Potential Research Gaps:
• In SDN devices, there is a necessity of power control algorithms.
• Energy-optimized traffic engineering techniques.

10. Intent-Based Networking (IBN)

• Research Problems: The translation process of superior business intents into minimal- level network tactics could be complex.
• Difficulties:
• The translation of automated intents into concrete network set ups might be difficult.
• Intent disputes identification and solution.
• Potential Research Gaps:
• For intent disputes identification and resolution, offer efficient AI-based methods.
• To verify and observe the consistent intents, implement dynamic models.

Conclusion

In SDN (Software-Defined Networking) projects, the above mentioned research problems and gaps critically emphasize the realistic issues. To develop SDN networks as more secure, scalable and productive, this research area provides vast possibilities for sufficient investigation and discoveries.

Suggestions for Future Analysis

1. Scalability:

• Through lightweight state synchronization, explore the distributed control plane models.

2. Security:

• For SDN components, examine the blockchain-oriented trust management.

3. Traffic Engineering:

• To forecast the actual-time traffic and QoS management, implement deep learning frameworks.

4. Multi-Domain Orchestration:

• Intend-oriented policy translation model has to be created for multi-domain SDN.

5. Programmable Data Planes:

• Clarify the data plane programming by designing high-level language abstractions.

What is the best topic for a PhD on software defined networking SDN and network virtualization?

On the subject of SDN (Software Defined-Networking) and network virtualization, select a compelling as well as practically attainable topic for your PhD project. Incorporating both SDN and network virtualization, we propose a model topic:

Suggested Topic

Title: “Adaptive and Secure Network Slicing Framework Using Intent-Based Software-Defined Networking for Multi-Domain 5G Networks”

Research Inspiration

The requirements for portable, secure and scalable network management is extended broadly due to the occurrence of 5G networks. SDN efficiently accesses the network slicing and to address various application demands, network virtualization ensures to send isolated virtual networks (slices). In portable resource distribution, cross-domain interoperability and security, the current models are still addressing the similar issues.

Significant Goals

1. Adaptive Network Slicing:

• For the process of accommodating with modifications of traffic patterns and application requirements, formulate an intent-based network slicing model.
• By using machine learning algorithms, execute proactive resource distribution.

2. Cross-Domain Slice Management:

• Across various network fields, develop a unified API model for effortless slice management.
• Among several SDN controllers, verify the compatibility and integrity of policies.

3. Security and Isolation:

• In order to reduce cross-slice assaults and assure traffic isolation, apply security techniques.
• Especially for secure multi-domain network slicing, implement blockchain or distributed ledger technologies.

4. Performance Optimization:

• To explain integrity, throughput and latency, utilize traffic engineering techniques to enhance slice performance.

Research Queries

1. How can network slicing be produced adaptable for efficient traffic patterns and application necessities?
2. How can secure and effortless network slicing be accomplished over several authority domains?
3. What security mechanisms are needed to verify traffic isolation among slices?
4. How intent-based networking can enable dynamic resource allocation in network slicing?

Research Methodology

1. Literature Review:

• Conduct an extensive analysis on virtualization algorithms, current network slicing models and SDN architectures.
• In flexible resource distribution, multi-domain compatibility and security, detect the involved problems and gaps.

2. Framework Design and Development:

• Intent-Based Network Slicing Module:
• For intended description and translation, develop a northbound API.
• Establish intent dispute identification and resolution techniques.
• Adaptive Resource Allocation Module:
• Reinforcement learning methods are applied for impactful resource distribution.
• An optimization engine needs to be created for actual-time resource management.
• Multi-Domain Slice Management Module:
• To manage the cross-domain slice, create a standard API.
• For secure policy implementation, execute DLT (Distributed Ledger Technology)
• Security and Isolation Module:
• Particularly for secure multi-domain network slicing, make use of blockchain technology.
• By means of programmable data planes, design traffic isolation techniques.

3. Simulation and Experimentation:

• To simulate a multi-domain 5G network platform, deploy NS-3, Containernet or Mininet.
• Regarding the cross-domain interoperability, acquire the benefits of numerous SDN controllers such as Floodlight, OpenDaylight and ONOS.
• Network slicing model needs to be established and its performance is assessed.

4. Evaluation Metrics:

• Adaptability: As a means to accommodate transforming traffic patterns, evaluate the potential of models.
• Isolation: Traffic isolation capabilities among slices should be examined.
• Latency and Throughput: Use latency and throughput metrics to evaluate the slice performance.
• Scalability: Across several fields, examine the scalability of the model.

5. Comparative Analysis and Refinement:

• In opposition to current slicing solutions, contrast the intended model.
• According to simulation findings and comparative analysis, optimize the design.

Anticipated Contributions

1. To accommodate effective traffic and application demands, an innovative intent-based network slicing model could be developed.
2. For effortless cross-domain network slicing, a secure and standard API might be created.
3. Security techniques are getting advanced for traffic isolation and policy implementation.
4. In 5G networks, improve the slice performance through optimization techniques.

 Critical References

1. Hu, Y., et al. (2021). “Intent-Based Network Slicing Management for 5G.” IEEE Network.
2. Khan, F. A., & Goudar, R. H. (2020). “Network Slicing Framework for 5G Using SDN and NFV: A Survey.” IEEE Access.
3. Foukas, X., et al. (2017). “Network Slicing in 5G: Survey and Challenges.” IEEE Communications Magazine.