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WAN aggregation, SDN the best next steps for network optimization

WAN aggregation allows continuous, high-performance networking, and software-defined networking delivers greater security, visibility and control. In this tip, expert John Burke evaluates both technologies to help you better optimize your network.

The linchpins of application delivery optimization (ADO) are now commonplace: Most WANs now include optimization,...

and most data centers have an application delivery controller (ADC) to load balance among servers and perform other services including various kinds of offload. In the continuous quest to make the wide area network better at providing the services users need, IT needs to be focusing attention next on WAN aggregation and on software-defined networking (SDN). WAN aggregation allows inexpensive Internet bandwidth and diverse last-mile WAN feeds to make connectivity continuous and high performing; SDN brings new levels of control, security and visibility to the WAN.

ADO mainstream

Nemertes Research's annual benchmark of enterprise IT has mapped the steady progress of WAN optimization from when it was a rarity back in 2005 to today, when more than 62% of companies have it or plan to deploy it in 2014 -- that's pretty much all the folks out there with a WAN big enough to optimize! Likewise, the use of load balancers and ADCs is becoming even more widespread as virtualized versions and ADC as a service (ADCaaS) options from major providers gain popularity.

Still room to improve

Of course, the backdrop for optimization continues to shift as well, and so trends in branching behavior, in connectivity and in networking technology are driving new ADO needs and technology.

Trends in branching behavior, in connectivity and in networking technology are driving new ADO needs and technology.

Nemertes Research has tracked a drive toward agile branching in the enterprise -- that is, a strategy of making branches smaller and less permanent, more attuned to market dynamics. IT needs to support this strategy by making branches easier and cheaper and faster to start up and shut down.

One of the key shifts is the rapid rise of both direct-Internet sites (those that do not send all their Internet traffic back through a data center) and Internet-only sites (those without a dedicated WAN link, most of which use a VPN across their link to the Internet to get to their data centers). This shift to Internet is driven by several trends:

•Increasing use of software as a service (which now comprises 25% of the average application portfolio).

•The decrease in prices for Internet services.

•The cost difference between Internet and dedicated WAN services.

•The fact that WAN links tend to be much slower to provision.

Folding in cheap and cheerful Internet

ADO has to expand to address the opportunities and challenges created by the rise of Internet links as WAN replacements or supplements. Link aggregation is the most important way ADO can take advantage of the Internet. ADO appliances and services need to be able to make all the connections feeding a branch look like a single, better, faster and more resilient connection. By aggregating multiple Internet links, or combinations of Internet and dedicated WAN connections, ADO devices can compensate for variations in Internet link performance while also making optimal use of cheap, easy and fat Internet pipes to improve application performance and availability.


Revolutionary changes are launching in enterprise networking at the same time IT is building the Internet-powered agile branch. SDN has moved steadily from being a Web-scale cloud-vendor science project to a broadly available feature set. SDN applications for the enterprise are appearing, and although only 6% of organizations in Nemertes' benchmark research have plans for deploying in production by the end of 2015, it's likely SDN will become a staple of enterprise networking within the next five years.

While the most obvious use cases for SDN involve changing how IT provisions and manages the data center network (and the data center components within the WAN), SDN will inevitably affect the whole network and, thus, encompass the WAN and ADO. Bringing the set of services ADO appliances can provide under general programmatic control will allow SDN controllers to use those capabilities to meet specific performance requirements and objectives with more flexibility. Of course, some kinds of ADO services may be delivered as SDN applications via generic data-plane devices, too, lessening the need for specialized appliances for many kinds of functions.

What to do now

IT needs to be exploring WAN connectivity options to improve branching agility and branch network reliability, so it needs to be exploring WAN aggregation as a part of its ADO strategy. IT should be actively testing link aggregation this year.

Likewise, IT needs to be looking ahead to SDN as the underlying organizing principle of its network in the long run, and in the medium term expect to deploy it in production -- data center, WAN and campus. In the short term, IT should be writing SDN-readiness (e.g., OpenFlow support) into requests for proposals and requirements documents for all network pur­chases. It should also be experimenting with applications, controllers and at least virtual (but preferably also physical) network assets. Free and open source apps, controllers and virtual equipment can make this low impact and quick to spin up.

Bringing both SDN and link aggregation to bear will help IT keep optimization in sync with the evolving enterprise network.

About the author:
John Burke is principal research analyst with Nemertes Research. With nearly two decades of technology experience, he has worked at all levels of IT, including as an end user support specialist, programmer, system administrator, database specialist, network administrator, network architect and systems architect. He has worked at Johns Hopkins University, the College of St. Catherine and the University of St. Thomas.

Next Steps

Get more info on WAN aggregation

Learn how to merge optimization, security and management of the WAN

Understand your choices when it comes to software-defined networking

This was last published in August 2014

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