SD-WAN is a lot of different things to different people and partners. So – what is it and how did it evolve? Why aren’t all SD-WANs equal, and what should you consider before you choose? What are the benefits? Read on for a quick introduction to all things SD-WAN.

What is SD-WAN: The background
Software-Defined WAN (SD-WAN), manages and optimizes a wide area network, and is designed to address the changing use of enterprise networks due to the growth of cloud computing and mobile devices. It is a more flexible solution than MPLS, better supporting a distributed and mobile workforce, and is more reliable and scalable than VPN-based WAN.

SD-WAN is implemented as a network of SD-WAN appliances connected by encrypted tunnels. Each SD-WAN appliance is connected to a set of network services (typically MPLS and some Internet services) and monitors the availability and performance of each of these services. Traffic reaching an SD-WAN appliance is classified based on application and prioritized using a set of centrally-managed priorities before being sent out over the best available network link.

SD-WAN makes it possible to replace MPLS, which is expensive and time-consuming to connect to new locations. It also allows security functionality to be distributed to the network edge, making it unnecessary to send all traffic through the enterprise datacenter for scanning before forwarding it to cloud services, a practice that increases latency and degrades application performance.

By converging networking and security functionality, an SD-WAN can eliminate the need to deploy expensive point security products at branch locations. An SD-WAN with a large network of globally-distributed points-of-presence (PoPs) can provide high-performance, secure networking with centralized management and visibility

The evolution
SD-WAN developed and deployed by most vendors follows proprietary models and will do so for many years to come. What has evolved and will help break down vendor lock-in solutions is the ability to support Network Functional Virtualization (NFV) on generic x86 hardware. This has led to a number of innovative approaches:

  • Using x86 NFV hardware means you can avoid vendor specific hardware, operating systems and management platforms.
  • Utilise more powerful and innovative chipsets and hardware solutions as soon as they come onto the market allows for increased performance and scalability.
  • Choose hardware from generic providers or select a vendor for x86 hardware (such as Juniper NFX or Cisco ENCS).
  • The rise of Open SD-WAN initiatives will drive a rise in the number of vendors providing solutions at the CPE than you may otherwise have used in the past.

Not all are equal
SD-WAN by most vendors differs greatly and not all vendors are equal. Many vendors fail to deliver beyond Active/Active paths to make the transition to bonded services.  Bonding allows elevated performance while still maintaining critical QOS criteria.

How to choose?
The selection of SD-WAN should be based on:

  • Economics
  • Tunnel Bonding requirements
  • Path Selection options
  • Application Policy Based Routing
  • Virtual Topology needs
  • SLA and QOS targets
  • Price Selection

The five benefits of SD-WAN:

  1. Reduced WAN costs. MPLS bandwidth is expensive, and it can take weeks or months to provision a new MPLS link, compared to days with SD-WAN and a mix of fixed and wireless solutions. The benefit should be thought of as reducing higher carrier prices services than MPLS service.
  2. Enhanced WAN performance. MPLS is very effective at routing traffic between two static locations, but the growth of the cloud and cloud native services makes this less useful to businesses. SD-WAN’s policy-based routing allows traffic to be optimally sent through the network based on the needs of the application and connected services running over the links.
  3. Improved WAN agility. SD-WAN also provides much more agile networking than MPLS. With SD-WAN the network layer is abstracted away from the applications, allowing the use of a variety of different transport mechanisms throughout the WAN. The different paths and technologies are utilized by the SD-WAN orchestrator to deliver seamless application delivery.
  4. Simplified WAN management. With MPLS, an organization may need to deploy a variety of standalone appliances to manage WAN optimization and security. With SD-WAN, these operations can be centralized, allowing organizations to scalably manage growing networks.
  5. Increased WAN availability. Finally, SD-WAN can provide dramatic redundancy and availability improvements over MPLS. With MPLS, adding redundant links is expensive. SD-WAN on the other hand, can route traffic over a different transport mechanisms at different cost in the case of additional demand or on failover during an outage.