What Is SD-WAN? Why It's the Future of Enterprise WAN

Despite the technological advancements that ushered in a new digital age, many aspects of traditional enterprise IT networks remain essentially unchanged.

In particular, for enterprises engaged in global business, traditional wide area networks (WANs) are still the workhorse of connectivity for connecting branch locations to the corporate backbone network. Like the traditional hard disk drive, WAN technology is no longer state-of-the-art in today's context.

In the past, enterprises could only control and optimize WAN connectivity by moving costly corporate resources to the cloud. The cloud had its benefits, but it also came with limitations.

Fortunately, a new option has emerged that's helping businesses of all sizes optimize their IT networks. It's called software-defined wide area network, and it's changing the way businesses use their WAN by altering the way they operate.

Software-defined WAN, or simply known as SD-WAN, is the next evolution of enterprise WAN technology. SD-WAN is similar to software-defined networking (SDN) in that it uses software to manage and control network resources and services. However, SD-WAN focuses explicitly on WANs.

A WAN links two or more local area networks (LANs) in different geographical areas. A WAN, for example, will connect a LAN in the main office in New York to a LAN in a distant office in San Francisco. The most straightforward concept of an SD-WAN is that it’s a WAN that connects remote locations using software and virtualization technology rather than conventional hardware such as routers.

This basic description, however, doesn't tell the entire story. Here's a more technical and thorough explanation. SD-WAN simplifies the distribution of WAN services to branch offices by using software and cloud-based technology. Software-based virtualization provides network abstraction, which simplifies network operations.

SD-WAN allows IT and business managers to conveniently, efficiently, and securely deliver Internet-based networking. It also provides a cost-effective alternative to organizations of all sizes suffering from lagging Internet connections.

Understanding the need for SD-WAN

Organizations have begun to quickly adopt virtualization as they continue to implement and understand cost savings and operational efficiencies. To understand why businesses are adopting SD-WAN, it's necessary to discuss the challenges plaguing businesses and their IT teams. It's necessary to discuss the issues plaguing IT teams and how SD-WAN solves these networking challenges to understand why enterprises embrace SD-WAN.

Hybrid networking issues

Transport methods such as multiprotocol label switching (MPLS), long term evolution (LTE), and Internet are all the different routes available to enterprises to select from. Ideally, the WAN should use all routes and dynamically choose the optimized path for users and applications to achieve the best service level agreement (SLA).

Businesses used to rely solely on MPLS, but now, even if another transport method is introduced, it's frequently used as a backup. The reason for this is that combining traditional WAN technology and routing protocols can make things incredibly difficult.

SD-WAN, on the other hand, can readily employ multiple transport mechanisms. For example, most SD-WAN solutions are transport-agnostic and can use MPLS, 3G, 4G, 5G, LTE, wireless Internet, or some other mode of transport. All of these routes are termed active-active, which means that when a node fails or slows down, it's replaced by another node in the network. The system will dynamically select the best route based on the network policies set by admins.

Inflated bandwidth costs

Organizations must ensure that their essential software or applications, whether they be customer-facing or internal employee productivity systems, are up and running at all times.

However, companies constantly deploy distributed architectures and business frameworks to be close to their clients and partners. They also expect their application's efficiency and reliability to be the same at the most distant branch location, which is linked by a WAN, as it is at the company headquarters or data center.

Enterprises have typically acquired and controlled private networks to achieve LAN-like efficiency. Multiple dedicated private networks are often introduced, one for each application.

These private networks, on the other hand, are costly. The enterprise's ability to support more challenging, real-time applications such as voice over internet protocol (VoIP), video conferencing, and virtual desktops are hampered because of this expense.

With SD-WAN, a business’ inactive backup paths become active forwarding paths using all of the available bandwidth at a site. Email, for example, isn't usually a time-sensitive application, and the bandwidth usage of the application can fluctuate. As a result, an email application wouldn't need a low-latency, high-quality route to deliver the service. Instead, this traffic will be detected and transferred over the least expensive path possible in SD-WAN. On the other hand, VoIP and video conferencing systems require low latency and a high-quality direction to meet the application's SLAs. The system will deliver traffic over a route that matches the application in SD-WAN.

Tackling security issues

With more applications being accessed from cloud and Software-as-a-Service providers in addition to conventional data centers, an organization’s security perimeter is no longer limited to the data center's demilitarized zone.

In reality, the whole WAN surface area is growing and changing. Recent security issues have demonstrated that vulnerabilities are increasingly focused on the WAN. Traditional networking and virtual private networks (VPNs) are static, which makes them unstable, difficult to maintain, and slow to deploy.

But with SD-WAN, that's not the case. Since policies are transmitted from a central controller to the entire WAN Edge by an application program interface (API), security services such as encryption and app firewalling are very easy to apply to the entire WAN Edge.

Migration to cloud environments

Businesses must adopt the best architecture to leverage cloud data centers and SaaS apps. In addition to dealing with day-to-day applications and branch deployment problems, IT must also brace for a seismic change in the computing world.

Client-server applications were the standard in the past. Today's apps are much richer and more diverse. Traditional private networks have been used by businesses to offer reliable, high-performance, and highly accessible connectivity to software hosted within an organization's headquarters and private data centers.

Cloud applications are hosted on servers that aren't part of a private company's network. With many of today's systems migrating from the company data center to third-party cloud platforms and SaaS ecosystems, network traffic patterns have shifted dramatically and have become unsustainable for application distribution.

Since no company can afford to forego the reliability, efficiency, and flexibility that a private network provides, an Internet-based cloud system is a near-ideal way to provide direct connectivity from each branch to the various cloud application destinations.

How does SD-WAN work?

SD-WANs are made up of encrypted tunnels that connect two sites. An SD-WAN system is installed at each location. Once connected to the local networks, these devices download custom configuration and traffic policies, pre-set by network admins.

The SD-WAN is in charge of routing and traffic control. Based on application policies and real-time traffic conditions, outbound traffic is routed along the most optimized path. If one of the last connections fails, the SD-WAN system switches to an alternate link and manages the traffic load using pre-configured network policies.

With policy-based management at the heart of an SD-WAN, businesses can define their dynamic path-selection policies. Several policies can be pre-set to meet specific business needs, such as granting high-quality transmission paths for critical applications to meet their SLAs.

SD-WAN architecture

SD-WAN is built on abstracted architecture. The SD-WAN network is split into two sections: the control plane and the forwarding plane. The control plane monitors the transmission of data across the network  while the forwarding plane, sometimes called the data plane is the true transmission process carrying the application and user data.

The system shifts the control plane to a centralized site, such as an organization's headquarters. As a result, the SD-WAN network can be operated remotely without having an on-site IT team.

SD-WAN edge: The network endpoints are located at the SD-WAN edge. A branch office, a cloud server, or a remote data center all fall into this category. SD-WAN edges are simplified to a position where a non-IT person in the remote branch can simply connect and power it up.

SD-WAN orchestrator: An SD-WAN orchestrator is the network's virtualized manager, supervising traffic and enforcing operator-defined policies and protocols. The orchestration layer coordinates the communication of on-premise and cloud data to and from distributed network services and resources, with policy-driven insertion of distributed network services. It’s a highly resilient and fail-safe control plane because it's independent of the data plane controls.

SD-WAN controller: The SD-WAN controller manages and allows operators or administrators to see the entire network from a single dashboard while still setting transport policies for the orchestrator to implement.

Features of SD-WAN

In recent years, Software-Defined WAN has taken the enterprise and internet service provider (ISP) world by storm. Once just a pipe dream of IT, SD-WAN now offers the ability to dynamically manage and optimize WAN traffic with the same ease and precision as other cloud-based services.

Network virtualization

SD-WAN works as a network overlay. This creates the opportunity to build pervasive global applications that are entirely transparent to the underlying network. The overlay is independent of transport media, offering a compelling alternative to traditional WAN solutions for establishing secure end-to-end connectivity between two or more widely distributed nodes.

Even from numerous service providers, multiple links combine to form a unified pool of resources, often known as a virtual WAN. Along with intelligent automated path selection, SD-WANs can provide high availability and performance for applications. It also improves resource utilization and simplifies the network.

Enabling interoperability

SD-WAN enables the gradual addition of assets when interoperating with existing systems and circuits. This is a significant benefit that results from the control plane's independence and isolation from the data plane.

SD-WAN also meets a critical design objective by allowing multiple circuits, routers, devices, and facilities to coexist and interoperate. APIs also enable businesses to incorporate new and existing management frameworks and easily monitor applications.

Providing a secure overlay

SD-WAN offers a secure overlay regardless of the transport elements. SD-WAN devices are authenticated only when they participate in the overlay.

Any circuit and service provider configuration would allow safe and encrypted transport. Besides, a separate control unit allows automatic setup and key management for a variety of network components.

Monitoring usage and performance

SD-WAN enables centralized control and visibility across a wide range of transport methods and service providers and overall control over connected remote locations. This feature provides business-level insight into things like device use and network resource use.

SD-WAN also provides users with comprehensive performance tracking. When combined with business rules, output management allows for intelligent traffic routing through diverse paths and services within the virtual WAN network.

Cost-efficient hardware

By using readily available hardware and network equipment or servers, SD-WAN increases cost-efficiency and flexibility. Due to the distinction of the control plane from the data plane, the data plane can leverage common hardware.

Virtual apps can be delivered remotely and use current or standard commercial off-the-shelf servers. The only drawback is that the initial server installation and configuration requires IT installations on-site. Larger branches, campuses, and data centers are expected to benefit from this.

Traditional WAN vs. SD-WAN

Traditional WAN technology has been the standard solution for IT and data networking infrastructure for a long time. Conventional WANs help businesses connect LANs together via routers and VPN and are also used to connect multiple office locations.

Traditional WANs depend primarily upon dedicated MPLS connections to ensure safe, direct connections for scalable and robust network traffic flow.

Here are the key differences between an SD-WAN and traditional WANs:

Security

Traditional WANs are efficient in providing secure networks. Over an MPLS connection, traditional WAN is secure since packets sent are private and packet loss is avoided. These private packets can only be used by the destined MPLS connection, enabling safe site-to-site contact.

On the other hand, SD-WAN provides end-to-end encryption over a VPN connection, ensuring the security of your data traffic. Additional protection layers such as a firewall, WAN optimization, and secure web gateway (SWG) can be quickly implemented and integrated using this technology to secure remote workers.

Prioritization and dependability

Standard MPLS-based WANs provide users with excellent quality of service (QoS) by virtually isolating packets and avoiding packet loss. This is usually done over a single carrier-grade circuit connection. However, it's essential to bear in mind that MPLS bandwidth is typically more expensive.

It's important to determine which traffic is given greater priority to help companies guarantee that their connections are not lost. Traditional WAN technology makes traffic predictability and stability a priority.

Research has shown that SD-WAN can reduce internet costs. Depending on its content and priority, businesses don't have to spend as much to upgrade their bandwidth as they can combine and balance network connections in a cost-efficient way. It's less costly to run SD-WAN on 4G, LTE, and broadband internet than the service provided by an MPLS network.

SD-WAN also enables users with choices of devices to transfer the most critical data traffic over the strongest network connection. This results in little to no packet loss and latency. When there's a failure, the traffic is automatically switched to a different link.

This dynamic management of traffic helps SD-WAN do a much better job when compared to legacy WANs.

Scalability

In comparison to SD-WANs, it's harder to scale legacy WANs. This is because extensive preparations and logistical assistance for setting up the equipment needed to start operations will have to be put in advance. This manual addition can take longer in organizations and reduce productivity, particularly for opening new branches.

SD-WANs provide a cloud-first approach. This means that SD-WANs aren't limited by the network's underlying hardware constraints, making it easier to scale.

Control

To be compliant, system policies must be uniquely installed on a per-device basis for traditional WANs, making it a tedious task for network admins.

On the other hand, SD-WANs provide a more granular control on the network. WAN applications and quality of operation are prioritized around the board. SD-WANs also provide users with real-time traffic control from a single dashboard.

MPLS vs. SD-WAN: How do they compare?

Most network providers have been pitching SD-WAN and MPLS against each other as the definitive solution to any network problem. They're listing SD-WAN as a futuristic tech that lets you ditch the standard MPLS network and save operational costs in the process.

SD-WAN does allow you to use less costly connections for specific business applications, which is true. In most cases, though, you won't be abandoning any of your MPLS links, even after you move to SD-WAN.

When connecting large data centers, you won't just rely on broadband. You'll need a prominent, strong link with consistent service levels, such as an MPLS.

Businesses can improve the efficiency of the current networks by using SD-WAN as an overlay solution. SD-WAN is user-aware, allowing it to direct traffic in real-time over the most optimized path for high efficiency and low latency.

Then when is MPLS better? When using it with a hybrid WAN, it can address issues that may arise with older WAN architecture. It removes latency as traffic passes through a data center by routing traffic directly to the Internet.

The MPLS path is used by all daily business traffic that needs to get to the data center.

Benefits of using SD-WAN

Unmet needs in day-to-day business operations are the primary cause of IT disruptions, which stifle development. Combining various WAN-related technologies is a demanding commitment for companies with a large number of branch offices. SD-WAN provides a robust set of business outcomes that address much of the unmet needs for businesses of all sizes.

If you're thinking about deploying SD-WAN, there are a few ways in which it can potentially benefit your business.

Enhanced business agility

Legacy networks with brittle, hardware-based, static architectures have hampered the agility required by modern enterprises. SD-WAN provides flexibility and automation in the network by dissociating the hardware-centric data plane from the software-centric control plane.

With SD-WAN come the benefits of SDN to networking. With the virtualization of transport links into a single pool of available links, IT teams can now mix-and-match transport links of various types from various ISPs, allowing efficient deployment and faster disaster recovery.

Ease of management

Zero-touch provisioning is the star factor of SD-WAN. It means that businesses can set up and start using their SD-WAN system right away. The SD-WAN edge then queries the orchestrator for the recent software updates and relevant business policies.

The ability to set up a branch network without any IT involvement is designed to make SD-WAN as easy as possible for the IT department.

Intelligent automation

Unlike conventional branch network solutions, SD-WAN dynamically routes traffic through intelligent automated path selection to SaaS portals or public cloud infrastructure, bypassing the data center.

SD-WAN solutions facilitate businesses to create custom policies for numerous branches from an interactive, UI-based portal. The same platform provides centralized control to all branches and WAN links, allowing IT teams to handle various ISPs more efficiently. The management portal provides real-time analysis, historical reporting, and troubleshooting software. These features will enable IT to centrally manage and troubleshoot problems, avoiding costly on-site visits.

Decreased rollout times

Lengthy deployment periods are one of the most challenging aspects of IT solutions. New hardware systems usually take six months or longer to be completely deployed. Deployment times are significantly reduced due to software solutions.

For example, if you use a traditional WAN for deployment, the process will be time-consuming and require extensive research from technicians and administrators. It may also necessitate the procurement of additional hardware. On the other hand, managers can deploy the SD-WAN solution in minutes. Often, all that's needed is a quick point-and-click operation.

Reducing overall costs

The volume of data traveling over a WAN grows exponentially as companies deploy an ever-growing number of cloud-based applications, thereby increasing operational costs.

SD-WAN provides significant business benefits for organizations with distributed divisions in terms of business mobility and the potential to take advantage of internet bandwidth economics – or, to put it another way, cutting down costs while delivering intelligent network connections.

Challenges of using SD-WAN

While many SD-WAN vendors promote SD-WAN as a self-managed, DIY technology, future users should be mindful of the inherent challenges that SD-WAN systems possess.

Security

While the option to deploy hardware and virtualized instances with pre-set traffic policies that a user can access through a UI sounds enticing, the risks involved are substantial. As businesses migrate to cloud networking, enterprise data shifts from data center sites, and the remote workforce expands. The Edge no longer defines the perimeter.

The problem IT teams face with SD-WAN is ensuring that each security function is appropriately implemented and tailored depending on each company's unique needs. For example, automated unified threat management (UTM) is an essential factor when comparing different SD-WAN vendors. IT teams face the difficult task of deploying systems depending on business requirements, making it imperative that they have the skills to recognize and implement the appropriate security protocols and ensure that the UTM is deployed safely and adequately.

Quality of connections

SD WAN's popularity stems from the fact that it makes it possible to use less expensive Internet networks for connectivity rather than private lines like standard WAN architectures do. SD-WAN also makes it easy to work with different types of networking. A 4G/5G/LTE link is a standard option for backup network services.

The challenge that businesses face is that different SD-WAN vendors use various methods to increase the quality of experience for a given connection. For example, forward error correction (FEC) is one of the most popular approaches. In FEC, the data packets are sent with additional parity bits or even entirely duplicated, in the hopes of getting a full copy of the packet when it enters the other end of the VPN tube with minimal error. This method is useful for transmitting data without the need for retransmission and necessitates CPU time on SD-WAN edge computers.

If businesses use reduced-cost, lower-quality connections, then the packets will be transmitted correctly over the WAN. Still, there will be a performance penalty, and users will experience a lower QoE depending on the application. Low-quality links are particularly problematic for voice and video traffic.

Bring your own device challenges

The freedom that cloud apps provide and the opportunity to use them on any connected platform presents new obstacles for network teams. Employees can use cloud solutions from their personal and work computers, but IT teams must decide whether such personal devices can connect to such a network.

Teams have to analyze traffic over the network in the same way as they would any other data traversing the WAN. Granular reports may be required for traffic analysis to identify traffic, depending on the risk that the organization believes is appropriate. Visibility into WAN traffic is critical because it enables IT teams to make the best policy decisions when implementing changes in the SD-WAN to accommodate BYOD challenges.

SD-WAN as a service vs. managed SD-WAN

SaaS is a software delivery model in which third-party vendors host and make applications hosted on cloud platforms accessible to users over the Internet. SaaS is a technology distribution model that's typically charged monthly or on a subscription model.

In the case of SD-WAN as a service, the end user is usually responsible for controlling, maintaining, and modifying the SD-WAN solution through a cloud-based interface. With SD-WAN as a service users have access to the most up-to-date features. Users pay for the features they use, and they can change the accessibility standards at any time.

A managed SD-WAN is a managed service in which all networking applications and facilities are fully outsourced to a Managed service provider or Communications service provider.

For managed SD-WANs, the service provider handles everything related to delivering the application or service, including the necessary hardware and software. The WAN service is monitored, managed, and secured by the service provider itself. Pricing is usually based on a one-year or multi-year service contract. It can be specific depending on factors such as the number of sites, ranges, connection rates, and associated SLAs.

Managed SD-WAN networks are a common way for IT organizations to offload the headaches of connecting their branches and data centers.

Top 5 SD-WAN software providers

SD-WAN is a hybrid application that combines the concepts of SDN with WAN connectors. Companies use SD-WAN to link corporate networks across vast geographic locations. It also helps remove a significant portion of the hardware and operational costs associated with connecting networks through cloud services.

SD-WAN systems are similar to various other IT infrastructure software and address multiple issues such as network stability, application performance, and IT admin needs.

To qualify for inclusion in the top SD-WAN category, a vendor must:

• Support multiple WAN connectors for interoffice connections
• Support VPNs, firewalls, and web gateways
• Synchronize networks across great distances
• Link SDN and WAN connectors to offer better internet access

* Below are the five leading SD-WAN vendors from G2's Spring 2021 Grid® Report. Some reviews may be edited for clarity.

1. Cisco SD-WAN

Cisco SD-WAN allows users to handle their WAN access from a single dashboard, making daily management and activities more accessible. Cisco SD-WAN is a cloud-managed or on-premises networking solution that connects all data centers, campus locations, WAN branches, cloud platforms, and remote workers.

The Cisco SD-WAN provides a single dashboard for centralized management so that the SD-WAN connection can be easily deployed while enforcing policies across thousands of sites.

What users like:

"The solution is powerful and simple. This is an excellent solution if you have many sites. The zero-touch deployment has the potential to save a ton of time and technical resources. The ability to create policies for bandwidth control is priceless. Technical support was excellent and helped with questions along the way during the install. They provided a fantastic value-add.

Network monitoring is greatly improved without having to purchase third-party applications to see how the network is performing."

-  Cisco SD-WAN Review, Allen A.

What users dislike:

"Deployment was not as quick as we would have wanted it to be, but once we got it set, we didn't have any major issues until now."

-  Cisco SD-WAN Review, Martin S.

2. Cisco Meraki SD-WAN

Cisco Meraki SD-WAN is a 100% cloud-managed SD-WAN that can be remotely deployed using zero-touch provisioning. Synchronization of security across thousands of sites is made faster with the help of templates. Using an intuitive web-based dashboard, the Auto VPN technology safely links branches in a few clicks.

What users like:

"It is very easy to configure. It includes a great variety of preconfigured profiles to implement policies according to the applications that are handled. The cost for small and medium-sized companies makes it very competitive. Within Cisco, comparing it to Firepower (ASA), costs can be reduced considerably.

It is important to note that SD-WAN is just one of the many features included in the equipment and with the same license. For example, the topic of content filtering and malware protection is already included."

-  Cisco Meraki SD-WAN Review, Oscar A.

What users dislike:

"Cost was initially a factor, however when bidding and comparing to other solutions - this was hands down the best choice."

-  Cisco Meraki SD-WAN Review, Eric P.

3. Oracle SD-WAN

Oracle SD-WAN provides a dependable, high-performance network for critical applications and services. Oracle SD-WAN eases the responsibility of provisioning, managing, and controlling IT networks, while also ensuring a stable and reliable network from clouds to data centers to the Edge.

What users like:

"The product works well, is easy to configure and manage, and the support is good. It has saved us more times than I can count when ISPs went down, and it has allowed us to ditch expensive MPLS in favor of basic (less costly) internet pipes."

-  Oracle SD-WAN Review, Martin L S.

What users dislike:

"There were some hardware changes early in the deployment, but that has seemed to stabilize, and we should be good on the current hardware platform for several years to come."

-  Oracle SD-WAN Review, Brian C.

4. FortiGate SD-WAN

FortiGate SD-WAN unifies WAN routers, WAN optimization, and security equipment into a single application-aware solution with automated WAN path management and multi-broadband support. Fortinet FortiGate Secure SD-WAN combines best-of-breed next-generation firewall (NGFW) security, advanced routing, and WAN optimization capabilities into a single solution, providing a secure networking WAN edge transformation.

What users like:

"The integration of SD-WAN within Fortiwan firewalls is a monumental advantage over other firewalls that don't have this feature.

SD-WAN works by adding two ISPs of preferably the same bandwidth and playing with the load-balancing algorithms. FortiGate SD-WAN supports the algorithms by volume, session, spillover, source IP, and destination-source IP. Simply choose the algorithm that best suits your needs, indicate the parameters, either weight or threshold, for SD-WAN to perform its magic."

-  FortiGate SD-WAN Review, Daniel H.

What users dislike:

"WAN network connections are limited only to Fortinet devices. When other devices are present, it is not possible to explore all the software characteristics. Another limitation is that it is most suitable for intermediate or advanced users with excellent network knowledge, although it's easy to perform initial configurations of the software.

It could result in being a little pricey for small companies. Hence it is most recommended for high network distribution companies."

-  FortiGate SD-WAN Review, Jose Carlos C.

5. Cato Cloud

Cato Cloud is a Secure Access Service Edge (SASE) platform that combines SD-WAN and network protection into a single cloud-native service. The platform is efficient in optimizing and securing device access for its users across all geographic locations.

Users can quickly switch from MPLS to SD-WAN, simplify connections to on-premises and cloud devices, allow safe branch Internet access everywhere, and effortlessly incorporate cloud data centers and smartphone users into the network.

What users like:

"Being able to manage all the offices and users in a single interface, and being able to turn on a new rule and have it roll out immediately has been great. It's also a relief not to have to wait for a reminder email or check the firewall to see if there's an update that needs to be installed. It gets done automatically while I sleep."

-  Cato Networks Review, Joanne R.

What users dislike:

"Currently, I have no dislikes related to Cato. If there were anything I could wish for, it'd be the ability to prioritize packets on our network, and I believe that is in development at Cato."

-  Cato Networks Review, Leslie C.

To SD-WAN and beyond

Enterprise networking is being reshaped by more than just cloud technologies. SD-WAN eliminates the need to deal with connectivity issues by combining public Internet with private networks built by SD-WAN providers. This results in a safer and quicker network with lower latency between public cloud services and private data centers.

Safeguarding your business network and devices should always be your top priority. Find out how companies can defend themselves from cyber threats with the help of a network security key.