Overview of Software Defined Networking (SDN)

The aim of this report is to throw light on the Software Defined Network, which is a revolutionary technology that is capable of revolutionizing networks through Control Planes and decoupling the data. This can be helpful in providing much end-to-end controls, flexibility, and agility that has been necessary for the cloud computing. This report presents a literature review on the SDN that describes about its layers, comparison with traditional networks and advantages and disadvantages over the traditional networks. A critical analysis has also been proposed in this report to describe the security issues and the countermeasures for these issues associated with the application of SDN.

SDN (Software-Defined Network) and its layers

Figure 1: depicting the three layers of the SDN

(Source: [3])

As described in the above picture, SDN consist of three layers including “data forwarding layer, control layer and application” as infrastructure layer, control layer and application layer. The lower layer is also described as data plane that is comprised of forwarding the network elements [7]. It is responsible for forwarding the data, gathering statistics, and monitoring the local information. Above this layer, there is control layer (control plane) that is responsible for the management and programming of the forwarding plane and thus defines the network routing and operations at the other end. It might comprise more than one or one software controllers “that communicate with the forwarding network elements through standardized interfaces, which are referred to as southbound interfaces [2].” Thereafter, the top most layer is the application layer, which is helpful in introducing additional network features for example manageability and security, assisting control layer or forwarding schemed and many more. [1] stated “it can receive global and abstracted view of the same network.

Comparison of Advantages 

The biggest drawback of the traditional network was that there was not any availability of the resource visibility at the network layer however, SDN is capable of providing network resource visibility. This allows the centralized controller to monitor the resource requirement. In traditional networks decision-making and intelligence are spread within the network and in SDN, it has been a centralized controller that can be helpful in reducing complexities [3]. Thus, SDN provides a simplified network hardware and eliminates the complexity with the layers of protocols. Traditional network deployment was much complex as even troubleshooting includes the archaic tools whereas, SDN’s centralized controller has the characteristic to be programmed.

Comparison of SDN and Traditional Networks

Comparison of Disadvantages

It has been much time consuming as compared to that of the traditional networks and that could be a major concern for the implementation of SDM network. Other drawback of SDM is that it is more expensive as compared to the traditional ones as the prototype has been made using the same material that has been used in the final product [6]. Because of the internal stresses passed through the layering process, the SDM prototype is weaker than that of the final product.

Critical Security Issues in SDN

Tunnel Bypassing and Packet Encryption: It is easy to treat the different payloads in the SDN because it has adopted the “flow-based forwarding scheme” that certainly allows the intruder to customize the packets in this network [4]. After the packets travelled to the other end, the inner packets automatically gets routed, decapsulated, and decrypted as it is based on the new network policy. Malicious users could use this window to skip the networking border and thus enters the control policy of the network.

DDoS Attacks: the control layer of the SDN is vulnerable to DDoS (Distributed Denial of Service) attacks as more than one compromised hosts distributing in the same network would might flood with packets to the network. [8] explains “Since not all rules will already be available in the switches’ tables, many queries will be generated and sent to the controller which ends up utilizing the controller’s processing power causing legitimate queries to be delayed or dropped.”

Compromised Controller Attacks: the intruders might be able to gain access to the controller through keeping the switches controlled through compromising or programming the controller. This compromised controller could be used to as a platform for the execution of the malicious code or drop each and every incoming traffics.

Mitigation and Countermeasures

For the above security issues, following are the countermeasures respectively:

Tunnel Bypassing and Packet Encryption can be addressed through the construction of models that is capable of identifying the type of encrypted packet’s load type on the basis of the traffic statistics analysis for example arrival timing of the interpacket or analyzing the message length and many more [5].

The solution for the second issue can be described as the replication that could be helpful in managing the network through multiple physical controller’s manager despite of the single user or controller. Whereas, the forwarding plane should be operating while the single programmer is involved in the configuration of the whole network.

There is the need of the resiliency against the third type of attack mentioned above and this type of attack could be fought with control replication [4]. Although, this solution will only be applicable if every controller has been installed within a single platform in manner to share and transfer the same threat or vulnerability and force the intruder to enter every one network once it enters the network of the single controller.

Conclusion

Based on the above report it can be concluded that SDN has been an innovative and emerging technology that could revolutionized the networking business. Through the embracement of the network automation, the organization would be able to significantly enhance the flexibility of the network and save a very large time. This paper discusses the three layers of the SDN and explained about the advantages and disadvantages of the SDN. It can be concluded that despite of have certain security issues the SDN is a far better technology for the networking as compared to those of traditional networking concepts and it could be much applicable and secure in the real-life implementation.

References

• Alvizu, R., Maier, G., Kukreja, N., Pattavina, A., Morro, R., Capello, A. and Cavazzoni, C., 2017. Comprehensive survey on T-SDN: Software-defined networking for transport networks. IEEE Communications Surveys & Tutorials, 19(4), pp.2232-2283.
• Baktir, A.C., Ozgovde, A. and Ersoy, C., 2017. How Can Edge Computing Benefit From Software-Defined Networking: A Survey, Use Cases, and Future Directions. IEEE Communications Surveys & Tutorials, 19(4), pp.2359-2391.
• Karakus, M. and Durresi, A., 2017. A survey: Control plane scalability issues and approaches in Software-Defined Networking (SDN). Computer Networks, 112, pp.279-293.
• Karakus, M. and Durresi, A., 2017. Quality of service (qos) in software defined networking (sdn): A survey. Journal of Network and Computer Applications, 80, pp.200-218.
• Khan, S., Gani, A., Wahab, A.W.A., Guizani, M. and Khan, M.K., 2017. Topology discovery in software defined networks: Threats, taxonomy, and state-of-the-art. IEEE Communications Surveys & Tutorials, 19(1), pp.303-324.
• Lee, S., Kim, J., Shin, S., Porras, P. and Yegneswaran, V., 2017, June. Athena: A framework for scalable anomaly detection in software-defined networks. In Dependable Systems and Networks (DSN), 2017 47th Annual IEEE/IFIP International Conference on(pp. 249-260). IEEE.
• Rawat, D.B. and Reddy, S.R., 2017. Software defined networking architecture, security and energy efficiency: A survey. IEEE Communications Surveys & Tutorials, 19(1), pp.325-346.
• Tsai, S.C., Liu, I.H., Lu, C.T., Chang, C.H. and Li, J.S., 2017. Defending cloud computing environment against the challenge of DDoS attacks based on software defined network. In Advances in Intelligent Information Hiding and Multimedia Signal Processing(pp. 285-292). Springer, Cham.