Defining a Role for SD-WAN in a 5G Era

Faster speeds, lower latency, improved reliability, greater capacity, and emerging capabilities such as network slicing is making 5G an attractive option for enterprises looking for agile WAN connectivity. There are a couple of reasons behind the increased adoption of 5G as a primary WAN connection:

As 4/5G plays a more prominent role in the WAN, how does SD-WAN need to evolve to support a WAN underlay that is now predominately wireless? The answer lies in looking at how cellular differs from traditional wired connections.    

1) Bandwidth fluctuations: With wired connections, bandwidth is fixed. However, in a cellular network, available bandwidth fluctuates based on signal strength and quality. Also, because the SD-WAN network extends to endpoints that could be roaming (vehicles leveraging redundant carriers), SD-WAN must adapt to moving in and out of different coverage layers and sometimes even different networks, including terrestrial and non-terrestrial.

2) Metered connections: Although unlimited data plans are available, they are not yet ubiquitous. Therefore, with some cellular links still metered, the ability to make intelligent traffic steering decisions based on data usage becomes important.

3) Differentiated services: One of the biggest limitations of broadband Internet as a WAN technology is the lack of ability to enforce QoS and, therefore, provide deterministic transport for critical applications. However, the next wave of 5G networks, called 5G standalone (SA) networks, will be able to support true end-to-end differentiated services through the implementation of a new feature called 5G network slicing. This feature will also provide carriers with the opportunity to support higher-level slices with a pre-determined SLA.

What is the role of network slicing in 5G?

Network slices are completely isolated virtual networks that operate on top of shared 5G infrastructure. These over-the-air virtual networks are provisioned on a single modem and single SIM card. Available only on 5G networks with a standalone core, each virtual network or “slice” is optimized for different application types by tailoring throughput, latency, speed, reliability, security, and more from end to end. With network slicing, cellular providers will not only serve users with "best effort " transmission but also with "deterministic " transmission.

The 3rd Generation Partnership Project (3GPP), which defines the standards for cellular telecommunications, defines four application categories for network slicing. 

Within each of these categories, operators can create multiple 5G network slices that would be uniquely tailored to specific business requirements. Today, the 3GPP standards enable up to eight slices on an individual modem/SIM to be configured. In future releases, this will extend to 32 slices. It will be up to the discretion of each carrier as to which slices they offer, how many slices they will enable, and if they offer service level agreements for certain slices (for example, within the URLLC slice). In addition, MEF has defined an end-to-end slicing framework that incorporates both wired and wireless access with slicing profiles. The framework was designed to allow slices to go beyond wireless networks and into the wired transport for a seamless experience.

How can SD-WAN facilitate the roll-out of network slicing?

In the same way, SD-WAN facilitated the migration from MPLS to broadband Internet, and it will also facilitate the transition from wired to wireless WANs in the enterprise. 

In a 5G SA network that supports network slicing, SD-WAN intelligence will initially be required on 5G enterprise WAN routers to create enterprise policies to dynamically assign corporate applications to the most appropriate slice.

One of the biggest values of SD-WAN devices is that they are equipped with powerful application recognition engines that can recognize thousands of corporate applications. These applications might be SaaS applications, or they might reside in the public cloud or the enterprise’s data center. They may even be custom applications built by the organization. With the knowledge of what network slices the carrier is extending to that enterprise, those applications can be classified by the administrator, and a policy can be created to ensure that the right applications are steered to the right network slices.

Although only a small percentage of 5G networks have been upgraded to SA today, network slicing represents a huge inflection point because it allows carriers to monetize their investments in 5G by being able to offer differentiated services to both consumers and enterprises. For enterprises, it finally gives them a WAN technology that is both flexible and agile and can also provide an MPLS-like SLA.  

The key to cellular providers moving quickly to market with network slicing is by leveraging SD-WAN intelligence on 5G enterprise routers. Therefore, SD-WAN is only going to grow in importance as 5G takes on a bigger role in the enterprise WAN and 5G networks are upgraded to standalone.

Camille Campbell is Senior Product Marketing Manager at Cradlepoint and MEF Member. (View her full bio here.)

(Editor’s note: This article is part of our regular series of articles from the industry experts at MEF.)