SD-WAN Architecture for Dummies

Software-defined wide area networking (SD-WAN) provides the framework for easily managed networking. The technology behind SD-WAN is built off of SDN (software-defined networking). Whereas SDN is designed for local area networks (LANs), SD-WAN applies similar technology to wide area networks (WANs). In this article, we’ll review the technology behind SD-WAN that makes it possible to provide a higher quality service, faster speeds, greater reliability, and enhanced security when compared to traditional WAN.

But first, we’ll take a closer look at how SDN works to help us better understand SD-WAN.

An intro to SDN

SDN is typically described as: directly programmable, centrally managed, agile, and programmatically configured. It’s typically based on open standards such as the OpenFlow protocol, Cisco Systems’ Open Network Environment, and Nicira’s Network Virtualization Platform. It’s a computer networking approach that gives administrators the ability to easily manage network services. It’s designed to support the more dynamic and scalable computing requirements of the modern enterprise, where information is increasingly being held offsite in data centers.

With SDN, the system that makes decisions about where network traffic is sent is disconnected from the system that actually routes traffic to the right destination. SDN is composed of three layers – an application layer, a control layer, and an infrastructure – and two planes – control and data. The control plane (for traffic routing) and the data plane (for traffic distribution) run on x86 hardware and support virtual network functions. SDNs were first used to bring flexibility and scalability to data centers.

How SDN and SD-WAN differ

While SDN and SD-WAN are built on the same basic technology, there are some subtle differences to consider, especially for businesses that are dispersed across a wide geographical area.

• SDN is an end-user programmable solution that permits simple configuration and management. SD-WAN programming, on the other hand, is generally handled by an SD-WAN carrier so the end user does not have to be involved. However, SD-WAN network management is centrally controlled, so adjustments across the whole network can be made on the fly.
• SDN is designed for local networks or service provider core networks, while SD-WAN provides connectivity over wide area networks, which consist of several local area networks combined. The internet itself can be considered a wide area network.
• SDN is enabled by network function virtualization (NFV) based on software designed to run closed systems. SD-WAN offers software defined application routing that may run on a physical SD-WAN appliance or a virtual appliance placed in the office, in a data center, or even in the cloud.

The advantage of SD-WAN

With SD-WAN technology, networks use application-based routing instead of packet-based routing, which allows businesses to rely on consumer-quality internet (which is less expensive than a private network) but with improved performance. This provides significant cost savings compared to multiprotocol label switching (MPLS), which is typically used to create private business connections.

SD-WAN offers improved agility and flexibility along with centralized business management for application routing. Improved control and visibility helps users identify applications running across the WAN and apply consistent use policies across an entire organization and suite of applications. With SD-WAN you can route priority applications to higher performing paths, ensuring that service for critical applications is never compromised.

SD-WAN users can expect a configuration that ensures proper load balancing, instant failover, few, if any, interruptions, and added security through the use of encrypted tunnels for data packet transmission.

Key SD-WAN features

At minimum, you should look for the following SD-WAN features when shopping for providers:

• Capacity to scale as your business grows
• Improved reliability over your previous WAN connection
• Simplified network management with a centralized portal
• Path selection and failover
• Improved link quality
• Ability to route high-priority applications through optimal paths
• Real-time packet-level monitoring
• The ability to turn your broadband connection into fast and secure connection, with the same (or better) reliability as a traditional MPLS connection

SD-WAN deployment

When migrating to SD-WAN, there are various decisions to make regarding your SD-WAN implementation. Vendors will offer several deployment models:

• Do-It-Yourself Model: This model is a primarily self-directed approach, but a third-party vendor will help deploy WAN endpoints. Your vendor will also generally be the first point of contact for support, but you manage the software yourself.
• Hybrid Model: A hybrid model employs a third-party network service provider to manage the controller software and service provisioning for you.
• Reputable Carrier Does-It-All Model: This model involves a trusted relationship with a reputable carrier to provide all SD-WAN services for you, so you can focus on running your business and stop worrying about network connectivity.

To ensure that SD-WAN provides improved opportunities for security, content management, and remote access to virtual private networks, you need an experienced provider to handle the rollout. Here are some tips to get you get started:

• Know your multi-site needs well into the future and communicate these to your provider. Choose a company that provides coverage for all of your existing and future locations to save yourself the headache of managing multiple providers.
• Tap into your existing network providers to find out what they know about SD-WAN and how they can help you manage a seamless transition.
• Compare the SD-WAN features that local carriers or vendors have to offer. Focus on the must-haves first. Make sure that the carrier you select can provide consistent service quality at all of your locations.
• Evaluate various SD-WAN service models and select the one that aligns with your business needs and recent connectivity investments.
• Interview potential service providers to ensure they offer the hardware, maintenance, and technical expertise to align with your current and future site requirements.

Because SD-WAN typically requires very little physical infrastructure, a full rollout is often seamless and won’t interrupt your day-to-day business activity. The key is to choose a provider that offers the right level of service to complement your internal capabilities. If you have an expert IT team, a do-it-yourself approach might be appropriate. But if on the other hand you have a multi-location business with little to no IT capacity, a carrier than can manage your SD-WAN for you is a better choice.

To learn more about the right approach for your company, please feel free to contact us and speak with an SD-WAN expert about your options. We’ll be happy to answer your questions and give you a clear idea about how an SD-WAN rollout for your company would look.