Dipping Your Toe: SD-WAN As Your First SDN

By now, you’ve probably heard about software-defined networking (SDN).  SDN can:

  • Separate the control plane of the network, which makes decisions about how traffic should be moved from place to place, from the data plane, which actually moves the packets
  • Virtualize networks, making it possible to overlay one or more logical networks on a given physical network infrastructure
  • Make networks fully programmable, to make possible automated network provisioning as well as automatic, dynamic, adaptive response to changing enterprise needs.

These capabilities are perfect for organizations increasingly automating and virtualizing their data centers as they build out private or hybrid cloud capabilities.  Data centers often seem like the logical first place to deploy SDN.

But there’s a catch: data centers are mission-critical, and most CIOs frown on the idea of rolling out an emerging technology as a mission-critical component in a mission-critical environment. Several companies we work with have experienced outages, hiccups, and challenges as they deploy SDN in their data center. Although their teams had expected issues to crop up and were able to resolve the outages reasonably quickly, a crisis is never optimal—and many don’t have the excess staff capacity needed to plan for and deal with such issues in their data centers while also maintaining necessary service levels.  Their staffs are stretched too thin to experiment, and they need either more hardened technology with well-tested deployment processes, or a lower risk environment in which to get comfortable with the concepts.

Enter SD-WAN. For networking professionals keen to test-drive the automation, programmability, and versatility that SDN provides, a better first step is likely to be implementing SDN in the wan.

SD-WAN implementations can offer easier and lower-risk opportunities to redefine a core network through software, and achieve radical improvements in performance, cost, and reliability even without requiring a significant re-architecture of mission critical infrastructure.

SD-WAN devices provide a secure, managed set of overlay networks across dynamically load-balanced network links (the more the merrier). Setting and refining policies in a central management console allows wholesale changes in WAN behavior to be effected without having to reconfigure all the routers in the WAN.

For example, it is typical in a WAN to set a policy for high-priority, latency-sensitive traffic that grants it top priority across the currently lowest-latency connection(s) available.  In a traditional WAN, this involves a lot of manual operations, often router by router configuration, and the routing tends to be all or nothing—you use one link for the traffic unless it fails, then fail over to another, and the failover can be slow (in network terms: taking tens of seconds to minutes).

In an SD-WAN, the decision about which link to use can be dynamic and real-time—made every second, or many times a second, or even packet by packet, with traffic rerouted as quickly as a problem with performance is detected.  (Think of this as similar to the way Google Maps delivers driving directions for your car: you’re automatically redirected to the least-congested or fastest route in real time.)  And, significantly, it is far easier to add new kinds of traffic to the priority class with a truly centralized management tool that treats the WAN as one holistic thing rather than myriad individual links and routers.

Here’s how to get started: Take a look at your existing WAN (likely MPLS, perhaps with a mix of carrier Ethernet and broadband/business Internet services thrown in). Look for sites that are currently experiencing either capacity or reliability issues, or both. Are you having challenges delivering high-volume applications like streaming video? Are outages interfering with business activities? Or are there applications you’d like to deploy, but lack the bandwidth for?

Locate a handful of such sites in your network, and deploy SD-WAN devices there, along with an additional circuit (Internet is usually fastest and easiest). You should see an increase in capacity and a reduction in outages at those sites—without affecting the rest of your network.

An added advantage is that with many SD-WAN devices, you’ll also get advanced reporting and monitoring capabilities. So you’ll have a better sense of what’s going on within your network, as well.

In sum, if you’re intrigued by the possibility of SDN but reluctant to muck about in the data center, deploying SD-WAN is a great starting point.

Categories: Software Defined WAN (SD-WAN), Application Performance/Application Quality