What is SD-WAN?

This is the first post in a series that we are doing on an exciting new technology available for business called “SD-WAN”, or Software Defined Wide Area Network.  We will be posting articles on the various types of SD-WAN, how they work and what sorts of problems they solve, but the first post is to give you the definition of SD-WAN and what applications it can have for your business.

What is SD-WAN?

SD-WAN is a technology that enables companies to use “commodity” internet connections, such as cable or broadband, to create secure, reliable and high-performance networks.  It does this primarily by combining multiple internet connections and managing them as one optimized connection.  An SD-WAN simplifies the management and operation of a WAN by decoupling (separating) the networking hardware from its control mechanism.   It is especially useful for networks that carry voice, video and cloud-application traffic because an SD-WAN will always use the most reliable connection for all traffic and it can prioritize traffic on congested networks.

Research firm Gartner has defined an SD-WAN as having four required characteristics:

  • The ability to support multiple connection types, such as internet, MPLS, frame relay and higher speed LTE wireless communications
  • The ability to do dynamic path selection, for load balancing and failover
  • A simple interface that is easy to configure and manage
  • The ability to support VPNs, and third party services such as WAN optimization controllers, firewalls and web gateways

The features of SD-WAN are reliability, quality of service (QoS), simplified network management and flexible deployment options.  The reliability comes from the technology’s ability to detect network outages on a link and switch traffic over to a working link.  SD-WAN supports QoS by having application awareness, which allows it to give priority to the most critical applications (usually voice and video).  Almost all SD-WAN implementations also provide simpler network management through the use of centralized administration – enabling admins to monitor and change network configuration from a central Graphical User Interface.  Finally, SD-WANs are flexible because they can be deployed using cheap and accessible network connections, rather than much less flexible T1’s or Metro-E connections. This allows an SD-WAN to be set up for a new location and added to the corporate network quickly, without waiting for long construction timelines.

What is SD-WAN Used For?

SD-WAN solves some old business problems in a new way, but it also solves some new ones.  We will have an upcoming article that addresses these applications in greater detail, but here are some highlights.

Failover, Network Reliability – Failover is the ability to switch to a backup network connection if your primary connection fails.  Because an SD-WAN is always choosing the best connection for your internet traffic, if one connection should fail, it will automatically switch your traffic to a different connection.  Moreover, a typical backup connection  is only used in the case of a failure on the main connection, which means that the backup connection is idle unless your main connection fails. That means you end up paying for bandwidth that you only use in emergencies.  An SD-WAN will use both connections all the time, so you can use your backup connection as additional bandwidth even while the main connection is operating.

Voice/Video Quality – One of the issues with internet connections is that they don’t support QoS, or Quality of Service, by themselves.  QoS is a technology that allows you to prioritize network traffic that is very sensitive to network congestion, like voice and video, over other traffic that is not sensitive, like email or file transfer. Adding SD-WAN to your corporate network allows you to provide QoS between corporate sites, and certain types of SD-WAN (explained later) even give you the ability to provide QoS over the public internet.

Corporate Network, MPLS Replacement – SD-WAN by itself cannot be used to replace MPLS networks, but combined with a technology called VPN, or Virtual Private Networking, it is a viable replacement or enhancement for MPLS networks. The issue with MPLS is that it depends on highly reliable and expensive network connections and it also requires the user to buy connections from a single vendor.  An SD-WAN can create highly reliable connections by combining cheaper commodity connections from multiple vendors, so by overlaying your SD-WAN connections with site-to-site VPN connections, you can replace an expensive and inflexible MPLS network with an SD-WAN network.  An SD-WAN can even include MPLS connections, so it can be overlaid onto existing networks.  We’ll discuss the pros and cons of MPLS replacement in a future post.

Cloud Optimization – SD-WAN is an internet optimization technology, so it should improve access to all of your cloud-based applications.  On top of that, many SD-WAN vendors are peering with cloud providers like, Microsoft Azure, Amazon AWS, Salesforce and many hosted voice providers to offer direct-peered, or near-peered access to those platforms.  These peering relationships will give you direct, high performance access to business-critical applications, with the security and failover protection offered by SD-WAN.

What’s Next?

Our next post on SD-WAN will cover how the technology works and the advantages of different implementations.  If you have any questions in the meantime about how SD-WAN can have an impact on your business, please feel free to contact us.

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