What is SD-WAN?

Posted on: June 7th, 2019 by David Debono

The software-defined WAN architecture or SD-Wan is paving the way for the future. If you are un familiar with the terminology, a single Wide Area Network (WAN) is a collection of local area networks (LAN) or computer networks within one or multiple geographic areas. When you hear the words “software-defined”, it means that the WAN is managed and configured via software so that it can adjust accordingly to meet business requirements.

SD-WAN technology is a gradual replacement of traditional WAN’s, we will now discuss some of the benefits and how the technology works.

How does an SD-WAN work?

The software-defined architecture has several characteristics attributed to its operation:

1. A singular or centralised means of control

Control within the software-defined architecture is centralised and is accomplished through the use of a GUI dashboard. Public clouds will often host these dashboards for direct use by users. This form of control is separated from underlying hardware and simplifies management of the network while simultaneously improving IT service delivery. The central controller will pass down operational rules to all WAN (virtual or otherwise) appliances, which significantly lessens the need to manage routers and gateways individually.

2. Multiple transport paths

Traditional WANs in past decades relied heavily on terrestrial MPLS connections in order to receive services. This usually entailed dedicated paths that are proprietary and often difficult to adapt to the business needs of the enterprise. SD-WANs are able to support hybrid WAN, meaning that SD-WANs have the ability to utilise multiple connections across multiple networks, including MPLS, 3G/4G LTE and other connection types. VPNs (aka virtual private networks) are established for each WAN connection as a way to segregate them from each other and keep data from spilling across.

3. Unified Communications

The SD architecture has the ability to dynamically select paths via a unified communications platform. Based on certain criteria —the WAN will selectively and automatically route data from one link to another based on characteristics or network conditions in real-time. Information may travel from one path to another if the network detects a degradation of one link or sees that it is completely down, or find a balance between all links that are available within the network. An SD-WAN also has the ability to ID and prioritise data packets by source/destination of data, user information, and application types, and route the appropriate information via any of the available links based on the characteristics of the data being routed.

4. Policies
An SD-WAN has policies that determine what paths data will flow through and what level of priority will be given to each path. In this context, it is actually easier to implement your business logic, rules and Quality of Service through the utilisation of a GUI console or dashboard. Compared to traditional routers and switches, company policies are immediately translated into operational rules and distributed via SD-WAN gateways and routers across the entire network.

In one example a policy can be generated to give video teleconference and VoIP communication higher priority and set the policy to take low-latency paths in order to mitigate disruptions of service and improve QoS.

Another example would be routing low priority data that doesn’t require high levels of security including backups across lower grade data connections, rather than across secure, encrypted connections such as the MPLS network. Any sensitive data that traverses across the WAN will be restricted to pass through dedicated VPN connections to ensure that the data remains secure and uncompromised. This serves to ease congestion and improve overall QoS.

By being able to effectively utilise multiple data links across an organisation, results in better utilisation of existing assets and reducing the requirement to upgrade the core network.

5. Chaining

One additional trait of the SD architecture is its ability to chain together with other services in the network. The WAN is optimised in order to improve application and network performance. Any data that leaves and enters a branch office can be routed through a VPN path to a cloud-based security service and strike a balance between cost, performance and security.

Benefits of SD-WAN

Enterprises recently opted to utilise the SD architecture do so for the following reasons:

  • Cost efficiency: Companies that utilise the software-defined approach may find it more effective compared to maintaining and operating traditional WAN circuits.
  • Ease of management: Managing a “Software Defined” network is less labour-intensive in comparison to a traditional WAN, where there is a heavy reliance on IT personnel to configure and deploy network devices correctly in order for data to be able to reach from one destination to another consistently.
  • Multiple configurations available: Enterprises have the ability to choose three different models to manage their network: the do-it-yourself (DIY) model, the managed IT model where an external vendor manages your SD network, or a hybrid model where your company and the vendor co-manages the network based on service level agreements between the vendor and your organisation.
  • Transparency: SD-WANs give enterprises full visibility across their network, while also leveraging multiple connection types for continuous IT services.


So what is SD-WAN? It is a software based network architecture and management system that takes advantage of the latest cloud computing and networking technologies to make it easier for businesses to manage and have more visibility and control over their networks, resulting in businesses being able to better and more effectively utilise their network and data infrastructure. Businesses used to rely on traditional WANs in order to conduct their day-to-day operations. Companies are quickly ditching older WANs in favour of the software-defined approach.

CircleBC in conjunction with TelcoBroker have been delivering Telecommunications Services and Telecommunications Consulting to hundreds of customers throughout Australia, including Sydney, Melbourne, Brisbane, Adelaide, Perth, Canberra and Hobart.