Understanding the Basics of SD-WAN

SD-WAN decouples the logical topology of your network from the underlying physical infrastructure and allows organizations to scale and adapt to changing requirements without costly hardware upgrades. Directing traffic to the best path and prioritizing business-critical applications boosts application performance and resiliency. It reduces costs by leveraging cost-effective Internet connections for underlay networks and VPNs rather than expensive MPLS circuits. L

What is SD-WAN?

Many still need clarification on what is SD WAN. Why it is vital for network operation. SD-WAN is a network architecture that supports application visibility, WAN optimization and security, all while providing cost and operational flexibility. SD-WAN software running on a centralized platform on CPE (customer premises equipment) monitors the conditions of public and private lines to determine where to redirect application traffic. For example, the default might be to send Voice over IP (VoIP) traffic over an MPLS connection. If that MPLS line becomes congested, the SD-WAN can automatically redirect traffic to a broadband Internet or 4G LTE wireless circuit. This approach reduces the need to backhaul traffic over a costly MPLS connection to data centers for inspection and security services. It also improves last-mile bandwidth by combining links using link-bonding technology. It enables enterprises to connect to the public cloud or SaaS applications more easily by providing direct internet access. Next-gen SD-WAN goes beyond basic network management by allowing the business to automate policy-based routing and traffic steering based on application SLAs. It also provides granular support for quality of service (quality of service), which enables IT staff to prioritize specific applications. It includes security capabilities such as micro-segmentation and zero-trust policies. Finally, automating zero-touch provisioning enables IT to ship small office/home office (SOHO) appliances directly to remote locations and have them auto-connect over existing internet or cellular connectivity.

What are the Benefits of SD-WAN?

The best SD-WANs build a virtualized overlay network with end-to-end encrypted tunnels and provide intelligent routing that prioritizes business policies. The technology monitors public and private links and can automatically switch traffic to the most appropriate path. For example, if an MPLS connection is congested, it can route voice-over-IP (VoIP) traffic over a broadband Internet or 4G LTE wireless link. This means the organization is more likely to meet SLAs and improve productivity.


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Additionally, suppose an employee’s home broadband network becomes unavailable due to storms or other reasons. In that case, the SD-WAN can switch that worker’s connectivity to a backup cellular connection without IT intervention. This helps ensure a reliable, high-quality work experience and eliminates employee downtime. SD-WAN is more affordable than MPLS and other connectivity technologies because it enables transport independence. This is possible because the software abstraction makes it possible to use various links, including low-cost broadband Internet or 4G LTE wireless, as backups for critical business applications. In addition, SD-WAN helps reduce costs by enabling a centralized configuration that minimizes human errors that can compromise performance and security. This is especially important as networks become more complex with multiple-point products at the edge. Many vendors of SD-WAN offer a range of solutions with different features, so it’s important to consider what is required for an organization before selecting. It can help read user reviews, attend vendor conferences and events, and seek testimonials from existing customers to get a more balanced, candid view of a product.

How Does SD-WAN Work?

In a traditional WAN network, information is sent from business offices to centralized data centers over different types of connections. These may include leased lines, fiber broadband, MPLS, 4G LTE and more. A traditional WAN may offer features like load balancing, WAN optimization and disaster recovery. However, these capabilities are often limited by the type of underlying transport service used in the network. The complexities of today’s business environment mean that many IT teams cannot rely on a single type of transport service to manage traffic across their WAN network. This can cause problems for businesses that depend on the cloud or use mobile workers. An SD-WAN provides the flexibility to support these applications and the varying requirements of different sites. Software-defined wide-area network technology uses a centralized policy engine to direct traffic based on application and performance requirements. This enables a network to dynamically select the best path for each application, avoiding costly over-provisioning and providing consistent QoE across locations. SD-WAN solutions can also remove the need for traffic backhauling, which involves sending traffic to remote data centers for inspection and security services. Instead, SD-WAN offers a way for IT to route traffic directly to and from the cloud or each site to their preferred internet service provider. This can reduce costs, improve performance, and eliminate the need for specialized and expensive hardware in the data center.

What are the Costs of SD-WAN?

SD-WAN offers several significant cost savings. A managed SD-WAN solution can significantly reduce or eliminate the need for expensive MPLS circuits. This can save enterprises an average of 50% per location. Secondly, an SD-WAN can also help to reduce costs by leveraging lower-cost internet connections for the WAN. This can result in significant savings in infrastructure and transport costs. Lastly, SD-WAN can reduce costs through application-driven routing and centralized policy management. This allows businesses to prioritize traffic based on business needs and automatically steer traffic to the best available path. This can improve the performance and overall reliability of applications across the WAN.

Organizations should first consider their specific needs to determine the costs of an SD-WAN solution. This includes understanding how many locations need SD-WAN devices, what size access equipment is required at each location (based on peak WAN utilization), the primary and backup internet services that will be used (and their cost), whether remote workers require an LTE cellular gateway for wireless WAN connectivity; and any additional security appliances that will be needed at each location. The hardware necessary to support an SD-WAN can be either low-cost or high-end, depending on the specific requirements. The intelligence is often located in the cloud rather than the device itself, which can reduce overall hardware costs.

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Osho Garg

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Osho is Tech blogger. He contributes to the Blogging, Gadgets, Social Media and Tech News section on TecheHow.