The difference between hybrid WAN and SD-WAN

The concepts of hybrid WAN and SD-WAN are often misused, and some people always think that the two concepts can be interchanged. Hybrid WAN is a way to route traffic over multiple connection paths, and software-defined wide area network (SD-WAN) simplifies WAN management by centrally managing and providing business policy orchestration and security. Both methods have evolved into important technologies to support the ever-changing network needs in the cloud era.

Networking in the Cloud Era

Private data centers host most applications, and the network uses Multi-Protocol Label Switching (MPLS), with all traffic being sent to the data center using application security protocols.

Currently, most traffic is destined to travel over the Internet. Global public cloud service revenue grew 18.5% in 2017 to $260.2 billion, up from $219.6 billion in 2016. AWS, Microsoft Azure, and software-as-a-service (SaaS) applications such as Microsoft Office 365, Salesforce.com, ServiceNow, and Box have now become an essential part of critical business infrastructure.

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In the cloud era, enterprises require networks to be more resilient, flexible and cost-effective. According to Gartner's Technology Overview for SD-WAN report: "From a price and performance perspective, public cloud computing makes traditional enterprise WAN architectures less than ideal."

For cloud applications, traditional MPLS backhaul technology will bring unacceptable performance degradation and network congestion. As consumption increases, MPLS costs are also increasing. As one of the solutions to this problem, some companies have opened backdoors on firewalls that can directly access the Internet. Although this method can improve performance, it will bring unpredictable security risks.

Other changes, such as new OTT applications for video streaming, have increased network congestion, and encrypted applications have made it difficult to prioritize applications, so all data is treated the same, no matter how critical it is. Finally, with the continued adoption of the Internet of Things, large amounts of data are being collected, stored, and often analyzed at the edge. These factors have had a profound impact on today's networks.

The evolution of hybrid WAN

A hybrid WAN is a way of routing traffic over multiple connection paths while taking into account the strengths and weaknesses of each link. Using path selection, a hybrid WAN can establish or redirect selected business and application delivery based on business policies and quality of service. When performance degrades or outages occur, traffic can be routed along alternate paths.

Hybrid WAN uses Internet broadband and traditional MPLS for path selection. As shown in the figure above, both Internet broadband and MPLS have their inherent advantages and disadvantages. Internet broadband is ideal for direct-to-cloud traffic and extra performance, and unlike MPLS, it can achieve extra performance without delays of months. However, Internet broadband has poor security and poor service quality, so it may not be suitable for internal financial applications and applications that require high-quality services, such as WebEx.

"The future of WAN is hybrid," said Shamus McGillicuddy of Enterprise Management Associates. "Most enterprises will operate networks that use a mix of public and private connections, with application traffic driving the choice of those connections."

SD-WAN simplifies hybrid WAN management

Managing a hybrid WAN is not simple, the command line interface (CLI) is manual, time-consuming and error-prone. Each device needs to be configured individually, or administrators can write custom scripts to configure and update complex network policies.

For example, a hypothetical retailer with 500 remote stores wants to deploy a new video application, requiring 10 new command line codes per router (5,000 command lines total). On average, each command takes 30 seconds to execute, and a total of one week to implement the change and roll out the new application. If something goes wrong, the administrator needs to check every one of the 5,000 lines of code. Scripts can help, but they also introduce greater complexity and increase the error rate.

Instead of requiring the use of a CLI, SD-WAN provides administrators with a centralized management portal to enforce business-defined rules across the organization. According to a Forrester survey, most network administrators want the ability to centrally monitor and manage traffic, as well as remotely configure the WAN.

SD-WAN abstracts network device management from the device, allowing network administrators to create business and security policies and deploy them across WAN, wireless/wired LAN, and cloud environments. This level of control improves IT and business efficiency and reduces operational management costs by approximately 20%. In addition to reducing operational costs, enterprises also use SD-WAN to improve application performance, directly optimize cloud connections, and improve network security.

Choosing the right SD-WAN solution helps ensure that application performance meets service levels and user expectations. Integrated WAN optimization capabilities can reduce network congestion and latency, thereby accelerating the performance of business-critical applications. Integrated user, device and infrastructure monitoring can help IT administrators quickly diagnose and resolve complex performance issues across local, cloud and mobile applications.

Using SD-WAN, enterprises can connect directly and securely to SaaS and cloud platforms. Administrators define policies to route SaaS applications directly over broadband connections to optimize performance and avoid the higher costs associated with MPLS. Applications built on AWS, Azure, or Google Cloud can connect over an Internet broadband VPN to ensure secure access.

Many SD-WAN solutions have firewalls, user identity controls, network segmentation, and other security features embedded. By segmenting traffic, network administrators can limit the attack surface and appropriately contain visitor traffic.

Network modernization

By providing traffic routing options based on business needs, hybrid WANs can improve congestion, reduce costs, and increase performance. However, without SD-WAN technology, it can be cumbersome to manage. SD-WAN solutions provide centralized management and orchestration for hybrid WANs, further reducing operating costs and increasing flexibility. For these reasons, industry analyst IDC expects the SD-WAN market to grow to $8 billion by 2021 as the technology becomes mainstream.