SD-WAN Buyer’s Guide – Optimizing Enterprise WAN + Top Vendors

Maintaining a robust wide area network (WAN) is among the more expensive and challenging aspects of managing an enterprise network. SD-WAN or software-defined networking is being rapidly adopted among organizations with a desire to optimize network traffic across multiple locations while helping to reduce costs and increase reliability.
Corporate data coming from branch locations is no longer simply just being piped back to central offices and is increasingly sent to remote locations in the cloud. This is true from several angles: Business software is moving toward cloud-based software as a service (SaaS) such as Office 365 and Salesforce, while companies have become more dependent on remote cloud infrastructure as a service (IaaS) such as AWS and Azure.

What is MPLS (Multiprotocol Label Switching)?

MPLS has become the standard technology for creating enterprise WANs. It establishes a private connection between two or more company locations and is essentially a private cloud that can cost upwards of 10x more than conventional broadband Internet connection while not offering the same amount of bandwidth. MPLS offers a series of priority queues or tiers into which application traffic can be tagged and mapped for quality of service. This allows MPLS connections to provide greater performance guarantees than if an enterprise were to pipe all of its traffic over the public Internet.
Looking back further than MPLS, older T1 connections are still used by some organizations today but have become largely insufficient for high demand scenarios such as those that involve lots of voice, video and multimedia traffic, as well as a large number of guest or customer Wi-Fi connections such as in a hotel or hospital.
Some companies even rely on local ISP broadband connection at each site but then use VPNs (virtual private networks) to establish a connection between those sites. While this approach is used by some organizations, it offers less performance, particularly for real-time applications such as a VoIP call, not least because VPNs add extra header information on each packet for encryption. Although MPLS connections provide a quality of service guarantee that can’t be matched by public broadband or other approaches to establishing enterprise WANs, MPLS technology has its shortcomings.

Again, the amount of bandwidth provided on MPLS is less than standard broadband Internet connections and yet MPLS lines can cost upward of 10 times more. It’s also expensive and time consuming to expand an MPLS network, which doesn’t have the same level of traffic prioritization capabilities as SD-WAN and may not be as reliable or resilient in the face of an outage. MPLS networks are less adaptable and flexible when it comes to managing and optimizing traffic flows, and given their limited bandwidth, companies will often over-provision the capacity required to ensure performance levels. In the event of an outage, backup connections are often in place but infrequently tested and may not work as expected. Failover to the alternative circuit may not be immediate, in which case session-based instances such as VoIP calls will be interrupted.
This is a key area where SD-WAN shines. In the presence of multiple network circuits, such as MPLS, wired broadband Internet and wireless 4G LTE, SD-WAN can route traffic across the best circuit in real time based on the status and capability of a given connection. Traffic can be provisioned and optimized in real time depending on the specific needs of individual applications and thousands of devices can be managed from a single virtual interface.

What is SD-WAN (Software Defined WAN)?

Amid the rapid adoption of cloud-based applications and services, a significant portion of corporate traffic is already moving over the public Internet instead of remaining inside a company’s WAN – whether based on MPLS or otherwise. SD-WAN can interface with many Internet and WAN circuits at once to dynamically route traffic across the best circuit. It monitors the quality of connections and the speed at which a specific type of traffic will reach its destination when traveling over a given route. By being aware of the performance between all connection points, SD-WAN can send traffic over the most efficient route possible, whether that’s your enterprise MPLS line or a 4G LTE connection. If one of these connections is lost, SD-WAN will automatically and instantly reroute traffic over an alternative circuit so that session-based applications such as VoIP calls won’t be interrupted.
Compared to the handful of options for tagging and mapping MPLS traffic, SD-WAN may offer dozens or hundreds of ways to map application prioritization. SD-WAN typically comes with capability of identifying hundreds or thousands of applications and the ability to map those application into traffic queues. So for example, a company might choose to route all internal unified communications and other internal traffic over MPLS while piping cloud application traffic, file transfers, and other latency-insensitive instances to business or consumer Internet services.

Core benefits of SD-WAN:

• More bandwidth at a lower cost than MPLS when paired with public Internet connections.
  More options when choosing connection types as SD-WAN works MPLS, cable or fiber Internet, DSL and wireless Internet.
• Centralized management across branch networks, which are connected to a single interface and managed from a single overlay.
• Greater insight into network performance with detailed reports and statistics that enable a more granular view of a network.
• Better performance via intelligent routing. SD-WAN chooses the optimal network circuit for a given application or traffic type.
• Improved reliability with nearly immediate failover. If one connection fails, traffic can be re-routed over an alternative network in less than a second.
• Highly flexible and scalable as bandwidth can be allocated where and when it’s needed, such as during peak loads or the roll-out of a new application.
• Quick deployment since the launch of a new office location can be accomplished with a standard Internet connection instead of MPLS, which is slower to deploy.
• Secure connectivity by providing encrypted tunnels and next-generation firewall tech.

Common Misconceptions About SD-WAN

SD-WAN will always improve network performance – While SD-WAN can improve the performance of your Internet traffic, simply plugging broadband circuits into an SD-WAN device won’t improve performance without ample configuration and oversight. And in the case of traffic that is routed over the shared public Internet, the pace at which it reaches its destination ultimately depends current congestion levels and delivery capabilities.
SD-WAN will drastically reduce your IT spending and network expenses – SD-WAN does save money by allowing the use of inexpensive broadband Internet versus private MPLS connections, and SD-WAN will help replace hardware infrastructure such as routers and firewalls at the network edge, however, IT budgets don’t always shrink overall because organizations often reallocate the money they save on cheaper Internet services etc. toward cloud and networking technologies such as SD-WAN itself.
SD-WAN is easy to deploy and maintain, just plug in the box! – This isn’t exactly true and SD-WAN implementations will still require networking experts to design, configure and integrate an SD-WAN solution with a legacy network. Likewise, organizations considering SD-WAN should anticipate a requirement for staff who are knowledgeable in SD-WAN for ongoing configuration, maintenance and performance monitoring.
SD-WAN is competing with and will replace MPLS connections – While often viewed as a competitor to MPLS, SD-WAN complements that technology and isn’t necessarily going to replace it. As a private, dedicated line, MPLS offers a better performance guarantee whereas SD-WAN with a broadband Internet connection must route traffic over the public Internet. MPLS will remain in use by companies who require guaranteed performance and such organizations should be rightly hesitant to rip and replace MPLS with SD-WAN paired with standard Internet.

The Bottom Line: SD-WAN Optimizes & Hybridizes WANs

While not ideal for the needs of every organization or the solution to every networking problem, SD-WAN can help maximize application performance across networks, particularly when it comes to traffic from cloud-based and media-rich applications and services. SD-WAN can enable a hybrid network comprised of both pricier dedicated MPLS circuits and less expensive broadband Internet connections at certain branch locations in a network.
By combining the capabilities of various network types, SD-WAN allows enterprise organizations to create a single network infrastructure that is more optimized, flexible, adaptable, reliable and affordable. Much of this is thanks to the dynamic multi-path approach SD-WAN takes to routing network traffic over a conventional Internet connection, as well as the greater number of polices available for traffic prioritization and load balancing. Although SD-WAN is being rapidly adopted, it’s not necessarily replacement for MPLS in organizations who need guaranteed service quality and many companies reportedly plan to keep at least some of their MPLS connections, albeit in an increasingly limited capacity.
Overall, SD-WAN is poised to disrupt the relationship that enterprises and their IT departments have with WANs over the coming years.