What Is a Software-Defined Wide Area Network (SD-WAN)?
SD-WAN is a software-defined approach to network connectivity that can lower operational costs and improve optimized business application experience.
Techopedia defines a software-defined wide area network or software-defined wide area networking, both abbreviated as SD-WAN, as “a wide area network that utilizes software components to control network operations”.1 Techopedia’s definition expands noting “[certain] management software virtualizes networking hardware in the same way that hypervisors and other components virtualize data center operations”.1
To better understand how SD-WAN works, it helps to first understand what a wide area network (WAN) is. Techopedia defines a WAN as a “network that exists over a large-scale geographical area, as compared to other network types, such as a local area network (LAN)”.2 LANs tend to be much more isolated than WANs, confining themselves to smaller networks in homes or business offices. WANs connect different smaller networks, such as LANs and metro area networks (MANs). This connection allows computers and users from one location to communicate with computers and users in different locations.
Techopedia notes that the SD-WAN’s software control mechanism helps manage all the different geographical pieces of its WAN, which helps to improve performance and efficiency. Specific protocols that the SD-WAN implements provide a user-intuitive interface and helps the WAN handle network traffic.1 SD-WANs can also support firewalls, gateways, virtual private network (VPN) tools and other features that increase privacy, cyber resilience and security.
SD-WAN offers businesses an optimized application experience. This application experience includes benefits like high availability for critical enterprise applications, coupled with predictable service and several hybrid active-active configurations, as opposed to active-passive configurations, links for network scenarios. SD-WAN allows for dynamic directing of application traffic using application-aware routing, providing a streamlined delivery and user experience.
Cisco notes that SD-WAN offers an “improved OpEx, replacing expensive Multiprotocol Label Switching (MPLS) services with more economical and flexible broadband, including secure VPN connections”.3 For more than 20 years, MPLS technology has helped power private connectivity. SD-WAN evolved out of this MPLS technology. Cisco continues noting that “SD-WAN can be seen as a software abstraction of MPLS technology that’s applicable to wider scenarios",3 bringing security-rich, private connections that are link and provider agnostic, and cloud-aware.
Comparatively, SD-WAN handles future scenarios using centralized policy-based, real-time traffic steering and MPLS handles these scenarios using backup links. Because SD-WAN unifies the WAN backbone, it produces comprehensive analytics throughout the global network.
Often presented as software-defined networking (SDN) for the WAN, SD-WAN is arguably the most widely deployed use case in SDN. Cisco notes that the SDN paradigm “became popular for abstracting network infrastructure in the data center and other sections within the enterprise perimeter.” SD-WAN performed similarly to SDN, however SD-WAN needed to abstract diverse elements of infrastructure, including those from different link types, geographies and SD-WAN providers.
While SDN is designed for working on LAN networks and for creating networks that can quickly be modified as needed, SD-WAN is designed for a WAN that connects different sites and supports a WAN from a large geographical area. Like an SDN, a SD-WAN removes the need for maintaining an abundance of network hardware. A SD-WAN can be used from an SDN where it provides the geographical capabilities of a SD-WAN and the scalability of an SDN.
While vendors control a SD-WAN service, an SDN is controlled by an IT administrator or user. Deployment tends to be easier for SD-WANs because users aren’t responsible for providing the service.
SD-WAN has the potential to solve a variety of cross-industry problems by using the following capabilities to create solutions:
With all the considerable capabilities and benefits that it offers, SD-WAN adoption is something that disparate businesses and organizations should consider when looking to improve their networks. SD-WAN deployment has greater potential benefits for enterprises that are reliant on IT applications that require frequent communication with the enterprise’s different geographic locations, individuals and devices.
Retail organizations that have several branch or remote offices need security-rich, cyber resilient networks that help ensure the protection of the data that it’s transmitting. This data can include credit card numbers, customer information and similar data that’s processed during payments.
Like most businesses with a wide array of employees, retail companies need networks that can support their employees and the work that they’re performing. Slow networks can result in numerous technical issues, many of which can impact productivity. SD-WAN technology helps provide organizations with the fast, efficient and security-rich networks they need to safely and reliably process transactions, and send and receive data, and for their employees to efficiently do their jobs.
Similar to the retail sector, the financial sector also benefits from the increased security and reliability that SD-WAN technology can bring to its networks. Financial organizations, such as banks, insurance firms and credit unions, require fast, reliable database access to process their customers’ transactions and information. For optimized functionality, financial networks need access to cloud services, an option not often found on private networks.
Arguably the sector that benefits the most from digital transformation is the education sector, which uses personal devices, digital curriculum and online assessments to meet the needs of today’s students. ITProPortal notes that in addition to scaling with each school or university’s bandwidth management needs, “SD-WAN allows universities to prioritize academic traffic and applications over the wants of the student population, [for example, students’ access to] streaming services, such as Netflix”.5 SD-WAN also helps schools to identify the different types of traffic, such as student, teacher, administrator and guest, and to scale according to those needs. SD-WAN is helping the education sector produce modern digital learning experiences with a higher bandwidth at a reduced cost for schools, universities, and similar public and private education institutions.
Network World notes that there are three main types of SD-WAN architecture, each with its own benefits that are generally rooted in how they use WANs. These three types of SD-WAN architectures are:
On-premises only architecture
True to its eponymous name, an SD-WAN on-premises architecture is found onsite and established using a SD-WAN box or similar plug-and-play router that performs traffic shaping from its location in real time. This onsite SD-WAN box doesn’t connect to a cloud gateway and only connects to your enterprise’s sites.
What are the benefits of on-premises only architecture?
Some of the benefits for SD-WAN on-premises only architecture include the following:
Unlike on-premises SD-WAN architecture, cloud-enabled SD-WAN architecture uses an onsite SD-WAN box that connects to a cloud gateway. This cloud gateway networks to the major cloud providers, such as Amazon Web Services (AWS), Microsoft Office 365 or Salesforce, and helps increase the performance and reliability of your enterprise’s cloud applications.
What are the benefits of cloud-enabled architecture?
Cloud-enabled architectures offer some of the same benefits of on-premises architecture, including real-time traffic shaping, increasing the performance of all WAN apps, multi-circuit load balancing, and increasing connectivity backup that improves DR.
If your enterprise’s internet circuit fails when you’re using a cloud app, then the cloud gateway can maintain that cloud session’s activity. If there’s another internet circuit, then the cloud gateway can prevent any interruption by instantaneously rerouting the cloud app to that internet circuit. With cloud-enabled architecture, cloud gateways can help improve both the performance and the reliability of cloud apps.
Cloud-enabled plus backbone architecture
The next level of cloud-enabled architecture, cloud-enabled plus backbone SD-WAN architecture, provides an onsite SD-WAN box that connects your enterprise’s site with the SD-WAN provider’s closest network point of presence (PoP). A PoP is where your enterprise’s traffic gets on the SD-WAN provider’s private, fiber optic network backbone. During the period when your enterprise’s WAN traffic is navigating the SD-WAN provider’s private backbone, it’s more likely to maintain lower levels of latency, jitter and packet loss. Lower levels of latency, jitter, and packet loss usually produce increased network traffic performance, most often with voice, video, virtual desktop and similar real-time traffic.
The SD-WAN provider’s private backbone is also directly connected with major cloud providers, such as AWS, Office 365 or Salesforce. As with non-backbone cloud SD-WAN architecture, this direct connection to major cloud providers helps increase the performance and reliability of cloud apps.
What are the benefits of cloud-enabled plus backbone architecture?
In addition to increased performance and reliability of cloud applications and increased performance of all network applications, including real-time apps, cloud-enabled plus backbone SD-WAN architecture has some other benefits. Benefits include multicircuit and ISP load-balancing, and increased DR capacity, as a result of boosted connectivity backup.
A survey recently concluded that enterprises that followed through with SD-WAN adoption received positive results, and SD-WAN users experienced the following benefits:
In an interview about WAN and SD-WAN, IBM Distinguished Engineer and Master Inventor Brian O’Connell and Distinguished Engineer Steve Currie discuss the Kyndryl SD-WAN service and the benefits enterprises experience when they migrate to it. It was argued in the interview that “SD-WAN isn’t just a new technology rollout, but a means towards new consumption models".9
Currie notes that enterprises have an incredible opportunity to “transform their IT business to drive technology to support them instead of shaping them.” He added that “businesses can shape the network to best address its market and [use] different technologies and capabilities to meet their requirements.” O’Connell notes that “customers can re-evaluate what they want their network to look like and how [it enables] their company to meet their customers’ demands”.8
It’s easy to get swept away in the rush to transform your network from a traditional and complex hardware-centric network to something flexible and modern. Today’s dynamic business needs must be met by networks that are agile and resilient, easy to manage and secure. These networks need to adopt the most recent innovations and cognitive capabilities and cut costs while fostering growth with newly enabled business models. Scalability is a must, and these networks require incorporated programmatic controls that can deploy applications anywhere from hours to minutes. SD-WAN helps meet these demands, delivering a veritable network transformation. It helps enable the application journey to the cloud with a service delivery platform that cuts cost through enabled automation, analytics and cognitive capabilities.9