Understanding Terminologies and Protocols of SDN

Posted on by FS.COM

Software Defined Networking (SDN) seems to be generating so much attention among the developments in the networking industry in 2016. As a new technology evolves, many terminologies and protocols try to define and describe their true meaning and purpose. Today’s post explores some SDN buzzwords and protocols which help readers to understand them better.

SDN Overview

Software Defined Networking (SDN) is comprised of multiple kinds of network technologies designed to make the network more flexible and agile. It is a programmable network that is configured using open software, so that it can be configured based on change in the requirement during deployment time as well as at later stage. The network architecture of SDN is quite a different concept from the traditional networking. As we know, in traditional networking architecture, network devices consist of both control plane and data plane. But SDN places the control plane function on an SDN controller which communicates with a physical or virtual switch data plane through a protocol called OpenFlow. As shown in the following picture, you can see how SDN differ from the traditional networking.


SDN Buzzwords

Whenever new technologies evolve, the need for consistent terminology is heightened. When we read the reference or articles about SDN, we will frequently meet these words:

SDN buzzwords

  • SDN: SDN, namely software defined networking, is an general term encompassing several kinds of network technologies aimed at making the network as agile and flexible as the virtualized server and storage infrastructure of the modern data center.
  • SD-LAN: SD-LAN is short for software defined local area network. It is built on the principles of SDN to create a new approach to adaptable, flexible, and cost-effective wireless and wired access network.
  • SD-WAN: SD-WAN, namely software-defined wide area network, is a specific application of SDN technology applied to WAN connections, which are used to connect enterprise networks such as branch offices and data centers that are over large geographic distances.
  • Open-Flow: Protocol used to configure flows, flow tables and TCAMs (Ternary Content-Addressable Memories).
  • OpenDaylight: OpenDaylight refers to an open, standards-based SDN controller platform project hosted by the Linux Foundation.
  • OpenStack: OpenStack is an open source “cloud operating system”. It is used to creat and manage pools of cloud resources.
  • CloudStack: CloudStack refers to an open source cloud computing software for creating, managing and deploying infrastructure cloud services.
  • Orchestration: Orchestration is a system to automatically create, initialize, coordinate & manage physical and virtual resources for cloud service delivery.
  • OSS: OSS is operation support system for short. It is a set of programs that help a communications service provider monitor, control, analyze and manage a telephone or computer network.
  • SDN Controller: An SDN controller is an application in SDN that manages flow control to enable intelligent networking. SDN controllers are based on protocols, such as OpenFlow, that allow servers to tell openflow switches where to send packets.
  • White Box Switch: White box switches, also called openflow switches, refer to network switches which come with an installed operating system, forwarding packets in a SDN environment. White box switches all rely on an operating system.
  • NFV: Network functions virtualization (NFV) is an initiative to virtualize the network services that are now being carried out by proprietary, dedicated hardware. It is highly complementary to SDN, but not dependent on it (or vice-versa).


SDN Protocols

While talking about SDN protocols, people always remember the OpenFlow. Actually, SDN is not equal to OpenFlow. In addition to the OpenFlow, there are other SDN protocols applied in SDN.


  • OpenFlow: OpenFlow, considered as the first SDN standard, defines an open protocol that enables an SDN Controller to interact with the forwarding plane of network devices.
  • NETCONF: NETCONF refers to a device (physical or virtual) configuration and management protocol which allows for configuration, data retrieval and event notification.
  • OF-Config: The ONF (Open Networking Foundation) specification for configuration of devices in an OpenFlow network. Specifies NETCONF over TLS (Transport Layer Security) with XML data models.
  • XMPP: Extensible Messaging and Presence Protocol is used by some (i.e. Juniper) as an alternative to OpenFlow. Preferred by some due to its maturity as a protocol.
  • OpFlex: A Cisco proprietary protocol proposed as an alternative to OpenFlow. Departs from a basic tenant of SDN in that control intelligence remains in the networking infrastructure.



SDN is not a new word now, but there are still many things of SDN required to be explored. As a newbie come to SDN, the first step is to understand the terminologies and protocols. Actually, the words of SDN are far more than those mentioned above, and that’s for you to discover. If you have any thought, experience, and knowledge about SDN to interact with us, you can send e-mail over info@fs.com.

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