SD-WAN underlays and why they Matter

Deploy a Wide Area Network (WAN) that uniquely fits your business

by Dana Stephenson and Michael Yuan

The perfect WAN?

Network technology is constantly evolving. You have more choices than ever when evaluating how to connect your offices, locations, data centers, and remote users.

One of the keys to deploying an optimal Wide Area Network (WAN) that uniquely fits your business is understanding the vast array of underlay and overlay options. Underlay offers connection or transport types such as Multiprotocol Label Switching (MPLS), internet, dedicated internet, fiber, and wireless broadband. Overlay options include Edge devices such as traditional IP routers, software based white boxes, and the vast array of software-defined WAN (SD-WAN) appliances.

You can also mix and match many of these technologies to create a hybrid network.

It’s internet. What’s the difference?

The internet is a popular underlay option for SD-WAN. Many SD-WAN solutions have features to mitigate potential performance problems associated with latency, jitter, or packet loss over public networks.

These issues and extended outages in the underlay vary greatly based on the type of service being used. Different network options make sense for different business scenarios. Broadband is typically a shared service where bandwidth is readily available, but due to the shared nature of the service, performance and availability are not guaranteed by service level commitments. Also, there is no Class of Service (CoS) prioritizing data traffic between sites.

By comparison, dedicated internet is not a shared service. It often does support network level Class of Service (Cos) and service level commitments for performance and availability.

Both options are open to the internet, and that can be good or bad depending on your priorities. Understanding the limits of an internet-based WAN is crucial in determining the right underlay solution for your critical sites. Those are the locations where you serve applications to your users or important data centers that connect to the cloud to serve your customers. You need to ask yourself, “What is my tolerance for downtime or fluctuations in user experience?”

It doesn’t have to be all internet: Hybrid MPLS + internet

Your network is only as good as your weakest link. Even though the internet continues to improve, it may not always be the right fit for your needs. One way to overcome this challenge is to diversify your network.

A diversified approach, one where you incorporate both a private MPLS and internet link, ensures your applications have access to a connection with highly stable and predictable performance.  

Whether you currently have a traditional MPLS Virtual Private Network (VPN) or are planning to deploy SD-WAN, you should consider using your MPLS to create a diversified, highly resilient network. MPLS has built-in security. It provides a private connection, plus rich CoS options, and guaranteed performance and availability.

AT&T SD-WAN with Silver Peak plus AT&T VPN

AT&T SD-WAN with Silver Peak is designed to take full advantage of MPLS capabilities such as Class of Service (CoS) to allow network-based prioritization of data. This provides an excellent user experience for key applications like Voice over IP (VoIP) and video. It also makes it easier to adopt SD-WAN if you have VPN.

Imagine you have an AT&T VPN network and are adopting SD-WAN. You may have complex CoS configurations developed over many years to support your most critical business applications. With some SD-WAN solutions, you may need to disable your AT&T VPN CoS and rebuild your business policies in SD-WAN. However, you don’t have to do that when using AT&T SD-WAN with Silver Peak. You can keep your established AT&T VPN CoS configurations as you use SD-WAN for optimal control and performance. MPLS links can be augmented with an internet connection to increase overall bandwidth while maintaining a highly secure, high-performance path for sensitive applications.

At the same time, you preserve your communication between your MPLS-connected SD-WAN sites and your MPLS-only sites, with no need to hairpin traffic through a gateway, adding unnecessary latency.

You can enjoy all the advantages of SD-WAN, MPLS, and low-cost internet bandwidth. Whether you are transitioning to SD-WAN, or planning to deploy a hybrid SD-WAN and MPLS network, MPLS-aware AT&T SD-WAN with Silver Peak smooths the transition while maintaining a highly secure, resilient, high-performance network for your business.

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