Software Defined Networking

Describe about the Software-Defined Networking for Open Networking Foundation?

Software defined networking and network function virtualization are being considered as the next breakthrough tool in the field of the computer networking technology. Through this paper, we aim to provide a detailed discussion of the basic concepts of this much studied technology.

The Concept

Software defined networking or SDN is one such approach to the management of computer networks which would allow the system administrators to manage the services provided by the network by the abstraction of superior level functionalities [9].  The control plane of a data network is used to select the destination whereas the data plane consists of the technologies and methods that are used for the transportation of data packets from the source to the selected destination. The decoupling of these two systems facilitates the abstraction process which is the key concept of the SDN technology.

The OpenFlow protocol is considered as the backbone of the SDN architecture: according to this protocol, a SDN essentially has the following characteristics:

Directly programmable: The network, being decoupled from the underlying data plane, supports extensive programming [4].

Agile: The traffic flow of the network can be automatically adjusted to meet the dynamic changes in traffic.

Centrally managed: Changes applied in the central controller (that are used for the maintenance of the global view of the entire network) is reflected throughout the network [2].

Programmatically configured: Dynamic and automated SDN programs can be used for configuring, managing, optimizing and securing the hardware and software components of the network.

Supported by open standards: The SDN architecture is supported by open standards, which eases out the tasks of designing the network and operating it [7].

The figure below provides a graphical representation of the essential components of a Software defined networking or SDN architecture.

Figure a: A schematic diagram of software defined networking architecture

(Source : [5] )

A detailed description of some of the essential components of a software defined networking architecture has been provided in the following section:

Business applications: The tools which are available to the end consumers, like that of the video conferencing tools, the supply chain management applications, the CRM application tools, etc [5].

The networking and security services: The methods and techniques that are used to provide relentless and secured networking services to the consumers. A large number of applications residing in layers 4 to & of the OSI model fall under this category: some such examples being security capabilities like firewalls, intrusion detection and prevention systems, WOC s, ADCs, etc [7].

Pure SDN switches: The pure SDN switches allow the central controller to manage all the functionalities of a traditional network switch.

Hybrid switches: These switches allow the simultaneous functioning of the SDN switches and the traditional switches associated with a particular network.

Hybrid Networks: A network supported by both SDN switches and traditional network switches, is often referred to a hybrid network [4].

North bound API: The application program interfaces that allow transactions between the control layer and the business application layer are considered as the north bound APIs. At present, there exists no standard north bound API [5].

Network Function Virtualization

South bound API: The application program interfaces that allow transactions between the control layer and the infrastructure layer are considered as the south bound APIs. Protocols that support such communication processes include the following:

Extensible messaging and presence protocol (XMPP)

Network Configuration Protocol [8]

iii. OpenFLow

The  Concept

One of the primary reasons behind the growing popularity of Software Defined Networking or the SDN is the fact that this particular architecture provides the facilities of network virtualization: a characteristic which allows the optimization and management of the network resources irrespective of their actual physical location, organization, and specification [1]. 

The virtualization of data networks is not at all a new concept:  virtual LANS or VLANS, virtual private networks or VPNs and virtual routing and forwarding (VRF)  are of the instances of network virtualization that have long been practiced by network administrators [12]. However, in the context of software defined networking, network function  virtualization refer to the process of defining and designing a network that would be able to provide end to end communications in a manner that the communication process is not affected by the behavior of the underlying physical resources of the network.

Figure b: A schematic diagram of Network Function Virtualization

(Source :  [12]

In this section of the paper, we provide a detailed description on how network function virtualization is achieved in software defined networks.

The methods used for such implementation include the following:

Technique 1: The Fabric-based network virtualization

One of the most common methods of implementing network virtualization is to run the functionality as an application or tool that would run on the SDN controller [11].  The said application would leverage the OpenFlow protocol, besides defining the virtual network.  The virtual network is defined by the policies that are used for mapping the flow of the data by the utilization of the headers of layer 4 to 7.

Technique 2: The Overlay-based network virtualization

Network virtualization can also be achieved by the utilization of encapsulation and tunneling procedures that would ultimately lead to the formation of several network structures relying on a common network of physical resources.  The resulting network architecture is often referred to as the overlay-based network virtualization [3].

The advantages of utilizing the software defined networking or SDN architecture, along with network function virtualization, are:

i. Provision of a centralized network: All software defined networking or SDN structures can be operated centrally, thus facilitating the optimized management of the network resources [3].

Enterprise management: A software defined network provides the network administrators to conduct experiments with the virtual networks without affecting the underlying network of physical resources.

iii. Granular security: One of the primary advantages of using software defined data networks is that such networks provide the mechanism for maintaining the security of the entire network and the devices connected to it in a centralized way [12].

Low operational costs: It has already been mentioned in section 2 of this paper that software defined networking or SDN architectures are supported by open standards: thus the cost of maintaining and operating such network architectures is much lower as compared to other network architectures.

Reduced capital investments: As software defined networking or SDN architectures facilitate the formation of virtual networks without making any changes to the underlying network of physical resources.

The following factors pose serious challenges when it comes to the implementation of software defined networking or SDN architectures in an organization:

Addressing the dynamic real-time changes: Although software defined networking or SDN architectures facilitate making dynamic and real time changes in the structure of the virtual networks, yet the unavailability of standardized protocols and methods for doing the same limits the utilization of the aid application [10].

Accommodating the on-demand changes of the network: The SDN architecture allows the network administrators to devise new networks dynamically. However, the platforms that are designed for the maintenance of the networks are not adequate for handling dynamic on-demand changes [6].

The discussion made in the sections above clearly indicate that in spite of the fact that the software defined networking or SDN architectures provide a wide range of facilities over the traditional data networks, yet the successful implementation and management of such networks have yet not been reported by many [6]. Extensive research is being carried out in this particular domain of computer science and technology and organizations like Ericson have reported that initial prototype models would soon be available.

However, it has to be kept in mind that SDN is essentially an architecture and not a technology by itself: and the development of technological application that would be supported by the SDN architecture are also being researched on.  Thus, it can be safely said the practical implementation of SDN architecture would be possible shortly [8]

Conclusion

The primary concepts of software defined networking and network virtualization have been discussed in this paper. The paper is based on information collected through secondary research works, which indicate that software defined networking architectures, in spite of existing in research levels, have the potential to drastically change the way in which network administrators take control of data networks. It is expected that the practical implementation of the said architecture would be able to provide the much needed agile and dynamic characteristics to the process of development of virtual data networks.

References

[1] Opennetworking.org, “Software-Defined Networking (SDN) Definition – Open Networking Foundation”, Opennetworking.org, 2016. [Online]. Available: https://www.opennetworking.org/sdn-resources/sdn-definition. [Accessed: 04- Feb- 2016].

[2]R.  Jain, “Introduction to Introduction to Software Defined Software Defined Networking (SDN) Networking (SDN)”, 2016. [Online]. Available: https://www.cse.wustl.edu/~jain/cse570-13/ftp/m_16sdn.pdf. [Accessed: 04- Feb- 2016].

[3]H.  Wen, P.  Tiwary and T.  Le-Ngoc, “Multi-perspective virtualization and software-defined infrastructure framework for wireless access networks”, Mobile Networks and Applications, vol. 20, no. 1, pp. 19-31, 2014.

[4]A.  Gladisch and W.  Kellerer, “Software defined networking and network function virtualization”, it – Information Technology, vol. 57, no. 5, 2015.

[5]Y.  Li and A.  Vasilakos, “Editorial: Software-Defined and Virtualized Future Wireless Networks”, Mobile Networks and Applications, vol. 20, no. 1, pp. 1-3, 2015.

[6]L.  Zhou, G.  Peng and N.  Chand, “Demonstration of a novel software-defined Flex PON”, Photonic Network Communications, vol. 29, no. 3, pp. 282-290, 2015.

[7]B.  Khasnabish, B.  Choi and N.  Feamster, “JONS: Special Issue on Management of Software-Defined Networks“, J Netw Syst Manage, 2015.

[8]L.  Liao, M.  Qiu and V.  Leung, “Software Defined Mobile Cloudlet”, Mobile Networks and Applications, 2015.

[9]D.  Bercovich, L.  Contreras, Y.  Haddad, A.  Adam and C.  Bernardos, “Software-Defined Wireless Transport Networks for Flexible Mobile Backhaul in 5G Systems”, Mobile Networks and Applications, vol. 20, no. 6, pp. 793-801, 2015.

[10]H.  Zamat and C.  Nassar, “Introducing software defined radio to 4G wireless: Necessity, advantage, and impediment”, Journal of Communications and Networks, vol. 4, no. 4, pp. 1-7, 2002.

[11]Y.  Wang, J.  Bi and K.  Zhang, “Design and Implementation of a Software-Defined Mobility Architecture for IP Networks”, Mobile Networks and Applications, vol. 20, no. 1, pp. 40-52, 2015.

[12]S.  Rass, B.  Rainer, M.  Vavti, J.  Göllner, A.  Peer and S.  Schauer, “Secure Communication over Software-Defined Networks”, Mobile Networks and Applications, vol. 20, no. 1, pp. 105-110, 2015.

[13]M.  Yang, Y.  Li, D.  Jin, L.  Zeng, X.  Wu and A.  Vasilakos, “Software-Defined and Virtualized Future Mobile and Wireless Networks: A Survey”, Mobile Networks and Applications, vol. 20, no. 1, pp. 4-18, 2014.