Software Defined Network
▶ Introduction

Software Defined Network (SDN) is an emerging network architecture where the network control is decoupled from forwarding and is directly programmable. This migration of control, formerly tightly bound in individual network devices, into accessible computing devices enables the underlying infrastructure to be abstracted for applications and network services, which can treat the network as a logical or virtual entity.

Figure 1 depicts a logical view of the SDN architecture. Network intelligence is (logically) centralized in software-based SDN controllers, which maintain a global view of the network. As a result, the network appears to the applications and policy engines as a single, logical switch. With SDN, enterprises and carriers gain vendor-independent control over the entire network from a single logical point, which greatly simplifies the network design and operation. SDN also greatly simplifies the network devices themselves, since they no longer need to understand and process thousands of protocol standards but merely accept instructions from the SDN controllers.

Fig. 1. SoftwareDefined Network Architecture

Perhaps most importantly, network operators and administrators can programmatically configure this simplified network abstraction rather than having to hand-code tens of thousands of lines of configuration scattered among thousands of devices. In addition, leveraging the SDN controller’s centralized intelligence, IT can alter network behavior in real-time and deploy new applications and network services in a matter of hours or days, rather than the weeks or months needed today. By centralizing network state in the control layer, SDN gives network managers the flexibility to configure, manage, secure, and optimize network resources via dynamic, automated SDN programs. Moreover, they can write these programs themselves and not wait for features to be embedded in vendors’ proprietary and closed software environments in the middle of the network.

In addition to abstracting the network, SDN architectures support a set of APIs that make it possible to implement common network services, including routing, multicast, security, access control, bandwidth management, traffic engineering, quality of service, processor and storage optimization, energy usage, and all forms of policy management, custom tailored to meet business objectives. For example, SDN architecture makes it easy to define and enforce consistent policies across both wired and wireless connections on a campus.

Likewise, SDN makes it possible to manage the entire network through intelligent orchestration and provisioning systems. The Open Networking Foundation is studying open APIs to promote multi-vendor management, which opens the door for on-demand resource allocation, self-service provisioning, truly virtualized networking, and secure cloud services.

Thus, with open APIs between the SDN control and applications layers, business applications can operate on an abstraction of the network, leveraging network services and capabilities without being tied to the details of their implementation. SDN makes the network not so much “application-aware” as “application-customized” and applications not so much “network-aware” as “network-capability-aware”. As a result, computing, storage, and network resources can be optimized.

▶ Research Issues

  • Efficient resource management for QoS in SDN
  • Centralized controller architectures API of SDN
  • CCN/ICN with SDN
  • Wireless communication with SDN
  • Network Virtualization techniques based on SDN

  • ▶ References

    1. Opennetwork :
    2. Openflow :
    3. NOX :
    4. N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner, “Openflow: enabling innovation in campus networks,” SIGCOMM Comput. Commun. Rev., vol. 38, no. 2, pp. 69?74, Mar. 2008.
    5. ONF, “Software-defined networking : the new norm for networks,” ONF(Open Network Foundation) White Paper, 2012. pp.279?292, 1992.
    6. N. Gude, T. Koponen, J. Pettit, B. Pfaff, M. Casado, N. McKeown, and S. Shenker, “Nox: towards an operating system for networks,” SIGCOMM Comput. Commun. Rev., vol. 38, no. 3, pp. 105?110, Jul. 2008.

    ▶ Achievements

    1. 문승일, 강형규, 홍충선, 이성원, "OpenFlow 기반의 네트워크에서 QoS를 보장하는 경로 관리 시스템", 한국통신학회 2012년 통신망운용관리학술대회 (KNOM 2012), 2012.5.3~4(4)
    2. 문승일, 강형규, 홍충선, 이성원, "OpenFlow 기반의 네트워크에서 QoS를 보장하는 최적의 경로 생성 알고리즘", 2012 한국컴퓨터종합학술대회(KCC 2012), 2012.6.27~29(29)
    3. 문승일, Rossi Kamal, 홍충선, 이성원, “OpenFlow 기반 네트워크에서의 Opportunistic 경로 플로우 관리”, 한국정보과학회, 제 39회 추계학술발표회(KIISE 2012), 2012.11.23~24(23)
    4. Seung Il Moon, Rossi Kamal, Choong Seon Hong, Sungwon Lee, "Towards Opportunistic Flow Management in OpenFlow", The 13th IFIP/IEEE Symposium on Integrated Network and Service Management (IM 2013), 27-31 MAY 2013, GHENT, BELGIUM