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SDN Journal: Article

Software-Defined Networking: The Promise and the Reality

Building simpler networks that, with the help of virtualization, are more intelligent and cost-effective

The enterprise is increasingly resorting to cloud services for many applications ranging from efficient application hosting or low-cost backup and archiving to cloud data centers. Typically, enterprise networks are interconnected to the Cloud over low speed IP networks that are limited in capacity and flexibility.

Over the next few years, however, enterprises will leverage the cloud for larger amounts of storage as they adopt Infrastructure as a Service (IaaS) and Platform as a Service (PaaS). This in turn compels the need for a more flexible and intelligent network capable of dynamically responding to rapidly changing IT demands, without bottlenecks, security vulnerabilities or data loss.

The impact of the cloud necessitates that Enterprise IT provide more focus on server-server connectivity rather than primarily supporting client-server interactions. This shift will also affect major service providers who must evolve their networks and corresponding business models to address the cloud, including significantly more rapid provisioning, multi-tenant, elastic network bandwidth, and far lower costs per bit than capable today. These are the primary drivers behind the emergence of Software-Defined Networks.

While there are a number of hurdles to wide-spread adoption, SDN is already emerging as a viable approach for the cloud. In fact, IDC predicts the SDN market for Worldwide Enterprise/Cloud Service Providers will grow from about $360 million in revenue in 2013 to $3.7 billion by 2016, a staggering increase of more than 900 percent in just three years.

What Is Driving SDN?
There are a number of drivers for SDN, including the exponential growth in mobile broadband, cloud computing and on-demand service delivery requirements.

There's no denying that consumers and businesspeople around the globe are increasingly relying upon smartphones, tablets, and notebooks. CTIA's recent semi-annual wireless industry survey reports that the continued growth of LTE networks and corresponding strong sales for smartphones in the US have led to mobile broadband usage more than doubling over the last year. In fact, the most recent CTIA data shows that US carriers handled 1.16 trillion megabytes of data between July 2011 and June 2012, up 104 percent from the 568 billion megabytes used between July 2010 and June 2011.

Among the fasting growing applications is mobile video. According to the Gartner Market Trends: Worldwide, the State of Mobile Video, 2012 report, the size of the worldwide mobile video market was comprised of 429 million mobile video users in 2011 and is projected to grow exponentially to 2.4 billion users by 2016. Smartphones and tablet sales will contribute 440 million new mobile video users during the forecast period.

Cloud computing is also driving the need for SDN. Gartner projects the growth in public cloud services to almost double from $110B in 2012 to $210 by 2016. Such growth is accelerated by technology advancements increasing the Virtual Machine Density, and rapid migration to 10, 40 and 100G Ethernet in the Data Center. Such change enables IT to stay in front of the cost curve, as network demands far outpace the growth in their budgets.

What Is SDN Exactly?
Software-Defined Networking or SDN is one of the most exciting developments in our industry today. It has the potential to unlock innovation and upgrade network efficiencies. To put it in a nutshell, SDN is an emerging networking architecture that allows for the decoupling of the network control layer from the data transport layer. The architecture then becomes dynamic, adaptable, manageable and cost-effective.

SDN is characterized by:

  1. Programmable control of the network through open APIs that enable IT and network operators alike to tailor the behavior of the network to their individual environments.
  2. Centralized Intelligence, where network control is provided across multiple network elements through an open interface, as opposed to today's autonomous system model where control is provided by each individual network element.
  3. Abstraction, where underlying details of the lower layers are masked from the upper layers. For instance, applications may request services independent of the type of transport. Furthermore, a common set of control software can run across multiple forwarding plane chipsets/implementations.

SDN architectures facilitate network automation, virtualization, and policy management, which are essential in supporting the inherently dynamic and unpredictable networking demands by businesses and consumers alike.

SDN for Service Providers
For service providers, SDN provides a more agile and intelligent network that can be programmed to allocate bandwidth from a shared pool of resources where and when capacity is needed. Figure 1 depicts the SDN Architecture, which consists of:

  • Application Layer: Where the service creation/delivery/assurance software resides, including cloud orchestration software
  • Control Layer: Where the network software (referred to as Network Services Modules) reside that provide intelligent network control
  • Infrastructure Layer: Where the transport and switching elements reside that provide network forwarding

Figure 1: Software Defined Networking Functional Architecture

In this architecture, SDN leverages a centralized controller that acts as the "brains" of the network and oversees and supervises the entire network and instructs the switches how to create new paths to handle different flows as needed.

An SDN-enabled service provider packet network can also be made more reliable and stable through globally computed, deterministic restoration graphs. Global network control combined with real-time analytics means higher service quality with fewer resources. Bottom line - this improves the user experience and decreases costs.

SDN in the Enterprise
SDN will also simplify network operations and management for the enterprise. Both Gartner and IDC predict that the crossover point, where more than 50% of x86 server workloads are virtualized, to occur over the next year. As private cloud deployments grow, networks must be automated to integrate with the cloud orchestration/operating systems. SDN makes it easier to transition to a secure, virtualized, multi-tenant network required for the cloud.

In addition, enterprises are coping with rising bandwidth demands from video applications, especially teleconferencing and distance learning. Mobility (especially BYOD) poses new access control and security challenges. SDN architectures offer the flexibility, bandwidth elasticity, and intelligent control to redefine the capability vs. complexity tradeoff that was previously unmanageable.

SDN can close the gap between compute and the data domains, which will allow network administrators to analyze massive data sets faster and more efficiently. In turn, this improves network capacity efficiency and operations automation, while also helping to increase revenue potential and service innovation. SDN will help IT managers to significantly improve the operations of their networks and allow them to tailor their network to specific applications and IT requirements.

IT leaders can use SDN as a tool to help transform their business. For example: enterprises can foster closer relationships by offering customers greater online access to select data over the enterprise network. For instance, a financial services firm can enable large corporate customers the opportunity for third-party reporting, governance, or even analytics firms to directly access enterprise credit card information, obviating the need for intermediate sites, manual process steps, etc., that are needed to provide sufficient isolation. An SDN would create virtual network partitions governed by stringent and limited access policies and security to minimize unauthorized access.

By providing direct access via the enterprise network, users are afforded a more responsive and current user experience, while simplifying network access and reducing costs.

Where We're at with SDN Today
Trends such as mobility, server virtualization, cloud computing, and the need to rapidly respond to changing business conditions place significant demands on the network - demands that today's conventional network architectures were not designed to support. SDN promises to provide a new, dynamic network architecture that transforms traditional network backbones into more intelligent service-delivery platforms.

While SDN adoption is at an early stage, it will take time before SDN predominates. Server, storage and other network infrastructure vendors are just beginning to implement SDN enablers such as OpenFlow into their product lines. We anticipate that wide-scale product availability will not come over the next few years. Additionally, organizations like the Open Networking Forum (ONF) are working aggressively to develop and standardize SDN architecture and practices, as well as the OpenFlow interface.

Carriers are in the earliest stages of SDN adoption. But, SDN is not necessarily new. For example, one of Ciena's largest service provider customers maintains that its Ciena CoreDirector-based mesh optical network is, in fact, an example of a software-defined network, which has been operational for many years. It is also important to note that in the enterprise, SDN is poised to happen in the data center first.

Early movers such as Google, which built G-Scale, a massive SDN effort, offer plenty of inspiration. G-Scale includes Google-built routers and switches embedded with the OpenFlow protocol, which can be programmed to automatically create and reconfigure connections between its data centers located all over the world for maximum resource efficiency. According to Google, this has helped to dramatically improve network utilization and substantially reduce overall costs.

Based on efforts such as Google's and others, there is no doubt that SDN will be critical in helping enterprises and service providers build simpler networks that, with the help of virtualization, are more intelligent and cost-effective.

More Stories By Marc Cohn

Marc Cohn is a Senior Director of Market Development at Ciena Corporation, where he is focused on Ciena’s strategy for Software Defined Networking (SDN). He is also the Vice-Chair of the Market Education committee for the Open Networking Foundation (ONF).

For over 20 years, Marc has drove and promoted successful communications products for systems, software, semiconductor, and services firms serving the Data Communications and Telecommunications markets. Prior to joining Ciena, he held senior marketing and product management roles with IP Infusion, Micrel, Amdocs, Lucent Technologies, Alidian Networks, and International Network Services.

Marc earned a MS EE degree from the University of Southern California where he was a Hughes Fellow, a BS EE degree in Electrical Engineering and was the first Computer Engineering graduate from the University of Missouri.

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Most Recent Comments
Michael Bushong 08/01/13 12:44:00 PM EDT

This is a solid writeup. When one technology trend hits, it is interesting. But we have three or four that are all landing (arguably all in support of cloud, yet another trend). With SDN, Big Data (analytics to drive some of the intelligence in SDN), DevOps (the programmatic glue that stitches it all together), and even things like photonic switching, we could be seeing a massive upheaval - the kind of once-in-a-generation change that leaves the landscape forever different.

With all of this change, I suspect that buyers will need to more aggressively take action. This requires a different type of leader - more change management than technology procurement. It will be interesting to see how this plays out and where adoption moves quickly and where it stalls.

-Mike Bushong (@mbushong)
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