Software-Defined Networking Is Here

We need a new network that's programmable and elastic. Software-defined networking (SDN) is emerging as the answer.

January 15, 2014

9 Min Read
Software-Defined Networking Is Here

By Khali Henderson

Houston, we have a problem! Basically, we’ve created a situation over the last few years wherein our computing has become virtual and dynamic, but our networking architecture remains static. So, we can initiate Microsoft SharePoint on a virtual machine in a hour, but we can’t bring up the bandwidth needed to run it during the same window of time. This is a simplistic example, but it underscores the point: We need a new network that can respond to the variable demands for connectivity and capacity. It needs to be programmable and elastic. It needs to be intelligent and application-aware. It needs to be virtualized not unlike servers and storage are today. And, for many, it needs to be based on software-defined networking (SDN).

Identified by Gartner Inc. as a top 10 strategic technology trend for 2014, SDN is an up-and-coming architecture that separates the control plane from the data plane in networking equipment, so that network intelligence and state are logically centralized, and the underlying network infrastructure is abstracted from applications.

In other words, SDN brings a similar degree of agility to networks that abstraction, virtualization and orchestration have brought to servers, Gartner analyst Joe Skorupa explains in a March 25, 2013, blog. The key takeaway is that SDN enables scalable and flexible networks that adapt to changing business needs.

“SDN’s ability to decouple network logic and policies from underlying network equipment allows for a more programmable network,” said Rohit Mehra, vice president of network infrastructure at research firm International Data Corp (IDC). “Providing better alignment with underlying applications, this programmability allows for greater levels of flexibility, innovation and control in the network. Logic and policies that can be defined, changed and modified result in a more dynamic network, providing the scale network administrators so desperately crave.”

This promise has gained the attention of enterprises and service providers as well as their incumbent networking vendors and a slew of startups like Big Switch. There are even several open source industry projects, such as OpenFlow and OpenDaylight, focused on developing protocols and platforms supporting SDN (see the special section, Open Source SDN Projects, following this article).  

Infonetics Research said among the vendors shipping SDN products in 2013 were Alcatel-Lucent, Big Switch, Brocade, Cisco, Cumulus, Dell, Extreme, HP, Huawei, IBM, Juniper, Midokura, NEC, Pica8, Plexxi, Plumgrid, VMware and more. The few early deployments for SDN, including those by Google, NTT, AT&T, Verizon, DT, BT and China Mobile, are in large data centers of cloud service providers and large enterprises, the research firm said.

This momentum is expected to propel the global  SDN ecosystem network infrastructure, applications, control plane solutions and professional services from $360 million in 2013 to $3.7 billion in 2016, IDC predicted in December 2012. A year later, in December 2013, Infonetics forecast a similar market opportunity for SDN technologies in enterprise and data center networking, growing to a $3.1 billion market by 2017. North America, where SDN got its start, will claim nearly 50 percent of the market in the next four years, the research firm said.

What’s Driving SDN?

The need for SDN is being driven by confluence on changes in the way we communicate and compute primarily the move to server virtualization, the explosion in mobile device use and the adoption of cloud-based services.

Each of these has caused network traffic to change. The Open Networking Foundation (ONF), authors of OpenFlow, explained in an April 2012 white paper on SDN that in the past, client-service applications generated “north-south” traffic between one client and one server, but today’s applications are distributed across multiple virtual machines, which exchange traffic flows with each other, creating “east-west” machine-to-machine traffic before returning data to the end user in a classic “north-south” pattern. Mobile users accessing applications from multiple devices, anywhere at any time further complicate traffic patterns as does enterprise use of cloud computing, which generates additional WAN traffic.

Conventional networks fall short under these circumstances, ONF stated, arguing they are:

  • Too complex Changes require so many touch points (often at the device level) that networks are left relatively static to minimize the risk of service disruptions.

  • Vulnerable It’s difficult to apply networkwide policies for access, security, quality of service, etc., particularly to mobile users, leaving organizations open to breach, or regulatory non-compliance.

  • Unable to scale Oversubscription no longer works to scale networks that have unpredictable traffic patterns as do today’s virtualized data centers or mega-Web companies like Google and Facebook with thousands of servers and big data flows.

  • Vendor dependent Responding to user demands for new capabilities is hindered by vendor product cycles and proprietary interfaces.

What Makes SDN Better?

In contrast, SDN is a new approach to designing, building and operating networks that allows systems administrators to quickly provision and program network connections on the fly without requiring physical access to the network’s hardware devices, explained analysts at Techaisle. They noted that SDN is like virtualizing the network in the sense that each switch may be part of multiple networks but subject to changes by a master network controller.

ONF explained the SDN architecture similarly: “Network intelligence is centralized in software-based 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.” (See graphic, Software Defined Network Architecture, below.)

The result is enterprises and service providers gain the ability to:

  • have vendor-independent control of the entire network from a single logical point, simplifying network design and operation

  • programmatically configure the network rather than writing lines of configuration code for thousands of devices

  • alter network behavior in real-time

  • deploy new applications and network services in hours or days instead of weeks or months

  • write SDN programs rather than wait for vendors as is customary in today’s closed software environments

  • implement common network services routing, multicast, security, access control, bandwidth management, traffic engineering, quality of services, optimization, policy management using APIs

What Are the SDN Use Cases?

Data Centers/Service Providers. Networking large data centers will be the first battleground for SDN, according to IDC in a March 2013 report. This will be driven by the requirements for hyperscale networked data centers built by specialist cloud providers like Rackspace, Amazon, Google and Microsoft, and, over time, by carriers like Verizon, AT&T, BT, Orange Business, NTT DATA, SingTel and Tata Communications, the research firm noted.

ONF said SDN offers communications, cloud and other service provider scalability and automation needed for utility computing by easing rollout of customer and on-demand services as well as self-service tools. The standards group also said SDN makes it easier to support multitenancy and to ensure network resources are deployed optimally.

Enterprises. “While a great deal of attention has been directed toward SDN in data center networks and service provider networks, it can also be applied to campus networks and enterprise WANs,” said Gartner’s Skorupa.

Infonetics Research agreed. “Wide scale in-use SDN deployments will occur first in the data center with large enterprise and cloud service providers, followed closely by the enterprise LAN,” said Cliff Grossner, Ph.D., directing analyst for data center and cloud at Infonetics in December 2013. “We’re already seeing significant use cases for SDN in the enterprise LAN providing security and unification of wired and wireless networks, and enabling BYOD.”

On enterprise campuses, for example, SDN’s centralized and automated control support voice/data/video convergence and anytime, anywhere access by enabling policy enforcement across wired and wireless infrastructures, according to ONF.

Enterprises also benefit from the same SDN advantages afforded to data center and cloud service providers. In the data center, SDN supports network virtualization, which enables scalability, while in a cloud environment, SDN allows network resources to be allocated in an elastic way, enabling rapid provisioning, ONF said.

Small and Medium Businesses. According to Techaisle there is even opportunity for SDN in the small and medium business market a haven for channel partners to the tune of $204 million by 2016. “SMBs that have some knowledge about SDNs exhibit enhanced interest to adopt them in next 12-18 months with the objective of reducing their network-related capex and managing their growth in cloud, mobility, big data technology usages,” the researchers said, noting SMBs that have virtualized their services and storage will be the early adopters.

A good SDN use case for SMBs could include implementation of virtual routed network on hypervisors, a Web-based unified management application for provisioning, monitoring and control of the entire distributed network. However, most SMBs will look for solutions with embedded SDN vis-a-vis HP’s new BYOD bundle that includes end-to-end management software and switches with integrated wired and wireless capabilities, and is extended with software-defined security.


was developed by the Open Networking Foundation (ONF), a user-driven organization dedicated to the promotion and adoption of software defined networking (SDN) through open standards development. OpenFlow allows direct access to and manipulation of the forwarding plane of network devices such as switches and routers, both physical and virtual. Separating the control from the forwarding allows for more sophisticated traffic management than is feasible using access control lists (ACLs) and routing protocols. Board Members: Deutsche Telekom, Facebook, Goldman Sachs, Google, Microsoft, NTT Communications, Verizon and Yahoo!

is a collaborative project at The Linux Foundation focused on building an open, standards-based software defined networking (SDN) controller platform that is suitable for deploying in a variety of production network environments. In addition to a modular controller framework, OpenDaylight is expected to include support for a number of standard and emerging SDN protocols, network services such as virtualization and service insertion, well-defined application APIs and data plane elements including physical device interfaces and virtual switch enhancements. Platinum & Gold Members: Brocade, Cisco, Citrix, Ericsson, IBM, Juniper, Microsoft, NEC, Redhat and VMware.

OpenStack Networking
, aka Neutron, is not a substitute for but a complement to OpenFlow and OpenDayLight. It is part of the OpenStack cloud operating system, which controls large pools of compute, storage and networking resources through a dashboard that gives administrators control while empowering their users to provision resources through a Web interface. Neutron is a pluggable, scalable and API-driven system for managing networks and IP addresses to ensure the network will not be the bottleneck or limiting factor in a cloud deployment and to give users real self-service, even over their network configurations. Neutron includes plug-ins that enable interoperability with various commercial and open source network technologies, including routers, switches, virtual switches and SDN controllers. Platinum & Gold Members: Aptira, AT&T, Canonical (Ubuntu), CCAT,  Cisco, Cloudscaling, Dell, DreamHost,  eNovance, Ericsson,  Hitachi, HP, Huawei, IBM, Intel, Juniper Networks, Mirantis,  Morphlabs,  Nebula,  NEC, NetApp, Piston Cloud, Rackspace, Redhat, SUSE, VMware and Yahoo!

Khali Henderson is editor-in-chief of Channel Partners.
Twitter: @khalihenderson


Learn more in the session, “SDN: Networking for the Cloud Age” at the Channel Partners Conference & Expo, Feb. 26-28, 2014, in Las Vegas.

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