Enterprises are looking alternatives for Multiprotocol Label Switching (MPLS) after so many years of use, with the hope of reducing their connectivity costs – related to hard cost savings. Enterprises spend a fortune on a managed MPLS network. This network is often a capacity restriction because more capacity substantially increases overall costs. SD-WAN is promising to break that paradigm by augmenting or replacing MPLS with affordable Internet last-mile connectivity.

But first, what is SD-WAN? Its acronym means “software-defined wide area network.”. A WAN is a connection between local area networks (LANs) separated by a considerable distance (from a few miles to thousands of miles). The term software-defined implies the WAN is managed and programmatically configured. So, it can be easily and rapidly adapted to meet changing needs. 

The means of control in SD-WAN connections are centralized. It often resides in a SaaS application running on a public cloud. Control is unattached from the hardware to simplify network management and improve the delivery of services. SD-WAN appliances (and virtual appliances) follow operational rules passed down from the central controller. It dramatically reduces the need to manage gateways and routers on an individual basis.

It also has multi-connection and multi-transport because SD-WAN gateways support hybrid WAN, which implies that each portal can have multiple connections using different transports. A virtual private network (VPN) is typically set up across each WAN connection for security. Consequently, the SD-WAN can be an overlay spanning a diverse communications infrastructure.

The policy based-management is what determines where dynamic path selection will lead to traffic and what level of priority (quality of service, or QoS) it has. Business intentions are implemented as policies via the central management console. New and updated policies are translated into operational rules and downloaded to all SD-WAN gateways and routers under control.

Cost savings can be realized by sending file back-ups across a broadband Internet connection. WAN traffic that requires a high level of security can be restricted to private connections between sites and required to pass through a robust security stack when entering the organization.

Another feature of SD-WAN is a dynamic path selection. It means the ability to automatically and selectively route traffic onto one WAN link or another, depending on network conditions or traffic characteristics. Packets may be led onto a particular link because another link is down or not working very well, or to balance network traffic across all available links. SD-WAN can also identify packets by application, user, source/destination, etc. and send them down one path or another based on those characteristics.

An additional characteristic of SD-WAN is the ability chain it together with other network services. WAN optimization (acceleration) is often combined with SD-WAN to improve network and application performance. Internet traffic leaving and entering a branch office may be routed across a VPN to a cloud-based security service to strike a balance between performance, security, and cost.

SD-WAN significantly increases ROI by improving IT agility, performance, and efficiency

The ROI should be in double digits, and you should expect to break even within a few months of completing your deployment. Make sure to plan your roadmap with your SD-WAN vendor and confirm that they can quantify ROI for your custom use-cases.

The price tag shouldn’t be the primary consideration with SD-WAN. If you focus solely on the initial investment, you’ll lose sight of the bigger picture, which is the ROI you should experience within a year of implementation.

SD-WAN promises an improvement in network agility. For DIY enterprises, it offers to automate network changes and increase network resistance. However, it does add “one more box to manage.” 

For companies that prefer a managed service, a new co-managed model enables IT to make quick network changed through a self-service model, while the service provider maintains the SD-WAN service itself.