What is SD-WAN and why will you use it someday?

Software-defined wide area networks (SD-WAN) are increasingly becoming the more efficient and cost-effective approach for businesses in Australia and around the world to manage their networks.  

Estimates suggest that 34% businesses globally will be investing in software defined wide area network (SD-WAN) and secure access service edge (SASE) in 2021, and the global SD-WAN market size is projected to reach US$4,137 million by 2027. This suggests that SD-WAN is well and truly on its way in, but what is it and is it something your business needs to keep on your radar?

What is SD-WAN?

You've probably heard of the term "software defined" bandied about thanks to the wide acceptance of software defined networking (SDN) and software defined storage.

SD-WAN is related to SDN in that they're both software-defined. SDN is an architecture that is meant for internal data centres at a campus or headquarter location, whereas SD-WAN is a technology you can buy.

The term is gaining attention for good reason, as the main benefit of software defined technology is flexibility, extra speed, and a better way to keep up with digital innovation.

While the technology isn't new, and neither is centralised WAN management. However, combining the centralisation with the technology's ability to dynamically share network bandwidth across connection points is making this approach popular.

What makes SD-WAN what it is?

According to Gartner, there are four requirements for a system to qualify as an SD WAN. These are:

1. An SD WAN solution provides a lightweight replacement for traditional WAN routers and are agnostic to WAN transport (that is, they support Multiprotocol Label Switching [MPLS], internet, 4G/LTE, etc.)
2. An SD WAN solution allow traffic to be distributed across multiple WAN connections in an efficient and dynamic fashion based on business and/or application policies
3. An SD WAN service dramatically simplifies the complexity associated with management, configuration, and orchestration of WANs
4. An SD WAN service must provide a secure VPN and have the ability to integrate additional network services

Business applications of SD-WAN

Organisations can use SD WAN technology for a variety of business applications, including:

• Aggressively moving applications to the public cloud
• Moving toward a hybrid WAN topology
• Reducing traditional business-class carrier service budgets
• Simplifying WAN management
• Reducing the cost of existing WAN remote branch equipment, often during a refresh cycle
• Managing a large number of remote branches
• Deploying video or other high-bandwidth, real-time applications to branch office locations
• Maintaining limited or no IT personnel on-site in remote branches.

Redmond Inc., a supplier of industrial and commercial products, uses SD-WAN to provide a reliable connection for phones, point of sale (POS), and fax networking to 10 branch offices from a central office based in Utah, USA. It's a far easier job today than it was a year ago, according to the company's technical project manager, Aaron Gabrielson.

SD-WAN particularly helped when it came to regional-based offices where traditional networking measures are often difficult and expensive. Gabrielson can now purchase cheap commercial-grade internet connections at rural branch sites and provide the sites with enough bandwidth to use voice over IP (VoIP) and process credit card transactions.

Centralised WAN management is also beneficial, notifying Gabrielson of any issues via a single interface and allowing him to easily manage and change bandwidth allocations where needed.

WAN versus SD-WAN

Many enterprises manage WAN at their branch by deploying a complex system of routers, WAN path controllers, WAN optimisers, firewalls, and other components. This is an expensive and high-maintenance approach.

SD-WAN bypasses this complexity by bundling together the important features of WAN infrastructure - path selection, and low cost.

Gartner estimates this approach can render SD-WAN up to two and a half times cheaper than traditional WAN infrastructure.

For example, a 250-branch WAN over three years is estimated to cost US$1,285,000 in a traditional WAN architecture. With an SD WAN deployment, it's only US$452,500.

The ability to use commodity routers is the biggest savings, along with staffing and a small decrease in router maintenance and support.

The benefits of SD-WAN

An SD-WAN approach offers businesses three key benefits:

1. Simplified management and operation

2. Reduced costs

3. Increased visibility and security.

1. SD-WAN provides agility via improved management

Gartner estimates that SD-WAN improves the time it takes for enterprises to provision network changes at branches by between 50% to 90%, due to simplifying operation, orchestration and zero-touch configuration. This, in turn, improves branch turn-up times.

2. SD-WAN reduces costs

Enterprises can anticipate significant savings by replacing traditional WANs with SD WAN technology. These savings come from reduced CapEx from infrastructure, software, and support costs at branch locations.

(Find out more about the benefits of shifting to OpEx for IT spending)

There is also reduced OpEx due to reduced personnel needed to provision, manage, and troubleshoot equipment. Finally, enterprises can save on NSP costs due to better utilisation of WAN connections as SD-WAN dramatically improves load sharing across multiple ports.

3. SD-WAN improves branch availability

SD-WAN improves overall availability of branches due to simplified failover as an SD WAN solution dynamically assign traffic to links based on application-centric policies, versus only IP addresses and circuits. Thus, they can more easily accommodate additional links, such as multiple broadband links or cellular connections. SD-WAN also supports faster failover and congestion detection than traditional IP-based routing protocols.

The solutions also offer better visibility over branch issues, as most solution are bundled with advanced analytics and troubleshooting functionality, allowing proactive maintenance. Finally, these deployments reduce manual configurations with a high degree of automation and orchestration, leading to reduced manual configuration errors, which are a leading cause of network outages.

(This post was originally published on 17 April, 2019 and has was updated and refreshed on 20 May, 2021)

What to read next:

Do your customers need SD-WAN? 5 questions to ask
The rise of software-defined networks
Why is network performance important?