Digital transformation (DX), edge computing, adoption of SaaS (Software as a Service) public cloud-based applications, and SDN (Software Defined Networking) are fundamentally changing the challenges associated with enterprise networking and WAN routing. This paradigm shift has lead enterprises to search for a solution other than MPLS (Multiprotocol Label Switching) to solve WAN routing problems. While MPLS still fits in well for select use cases, adoption is leveling off as it simply isn’t flexible enough to meet the challenges created by this new wave technology.
Given the new demands placed on organizations to optimize WAN routing to meet the optimization challenges and bandwidth demands created by these new technologies, SD-WAN (Software Defined Wide Area Network) has seen a tremendous surge in popularity and that trend is expected to continue. As reported by IDC, worldwide SD-WAN infrastructure and services revenue are expected to reach $8.05 billion USD in 2021, representing a CAGR (compound annual growth rate) of 69.6%.
However, it is important to note that not all SD-WAN solutions are created equal.
While SD-WAN will in general offer inherent benefits over MPLS, the approach you take to an SD-WAN implementation can make a huge difference on performance, and reliability. At a high-level, there are three distinct approaches to SD-WAN: appliance-based, service-based, and cloud-based.
In this piece, we’re going to dive into the pros and cons of the appliance and service-based approaches and explain how cloud-based SD-WAN solutions strike a happy medium between the two and enable enterprises to nail WAN management by optimizing performance while minimizing cost and complexity.
Appliance-based SD-WAN: enhanced control & increased complexity
As the name implies, appliance-based SD-WAN solutions are based around appliances that are generally purchased and configured by the organization that will use them. This approach to SD-WAN offers a fair amount of flexibility and control as users can select from a variety of ISP connection options to avoid being locked into a particular vendor and make changes as they see fit.
Despite the potential control and flexibility benefits of appliance-based SD-WAN, many organizations are moving away from it due to the challenges. The two main problems with appliance-based can be summarized as:
1. Lack of reliability– Appliance-based SD-WANs do not come with a carrier-backed SLA (Service Level Agreement). This places almost the entirety of the uptime burden on the user, which can become a nightmare when an application crosses multiple backbones and you must deal with multiple connection providers to determine the root cause of a problem. This can be a deal-breaker when it comes to successfully running applications that require high-performance such as VoIP (Voice over IP).
2. Complexity- By taking an appliance-based approach to SD-WAN, enterprises must find a way to patchwork together a comprehensive enough solution to connect a variety of endpoints that potentially span the globe. Simply identifying the right ISPs and backbones to leverage can create a significant amount of work, let alone the provisioning. Additionally, appliance-based SD-WAN is NOT secured “out of the box”. This means that enterprises must invest heavily in securing the traffic that traverses their appliance-based SD-WAN.
Service-based SD-WAN: reduced complexity, increased cost & limited flexibility
Due to the challenges of appliance-based SD-WAN, there has been a rise in popularity for service-based (aka managed) SD-WAN solutions. These solutions enable an enterprise to purchase an SD-WAN service that enables them to offload the support burden and complexity of appliance-based SD-WAN to an SD-WAN carrier. This generally solves the complexity and lack of SLA problems found with appliance-based SD-WAN, but comes with some less than desirable tradeoffs as well. The two biggest disadvantages of service-based SD-WAN are:
1. Increased cost. In a nutshell, a managed SD-WAN solution is effectively rolling SD-WAN and security appliances into a carrier-backed bundle and charging a premium. The nuts and bolts aren’t much different than appliance-based SD-WAN and the economy of scale benefits can easily be wiped out by the service premiums. This leads to managed SD-WAN solutions often being rather expensive.
2. Limited flexibility. With service-based SD-WAN, you are locked in to one carrier. This means not only are you limited by the scope of the carrier’s service, you are also limited by the responsiveness of their support teams. This can create significant operational challenges when changes need to occur, or complex issues need to be tackled. Locking yourself in to a provider can be a big risk that is difficult to hedge against.
Cloud-based SD-WAN: reduced complexity & cost with increased reliability & flexibility
Enterprise-grade cloud-based SD-WAN (aka SD-WAN as a Service or SDWaaS) enables enterprises to take an approach to SD-WAN that solves the problems of the appliance-based approach while minimizing the downsides of service-based SD-WAN.
Cloud-based SD-WAN solutions offer uptime and performance backed by SLAs and supported by a variety of Tier-1 ISP backbones and multiple PoPs (Points of Presence). These connections are secure and optimized to meet the challenges of the modern WAN. This aspect of cloud-based SD-WAN demonstrates its advantages over appliance-based solutions, but what about managed-solutions?
That’s where the self-service capabilities made possible by cloud-based SD-WAN really shine. They offer organizations the flexibility and freedom to shape traffic (e.g. using QoS) and make routing changes (e.g. using policy-based routing) on demand. This solves the problem of being hamstrung by the limitations of a given carrier and their support team. Additionally, the shift away from appliances and to the cloud enables cost savings and performance benefits for Internet-facing traffic.
The takeaway: cloud-based SD-WAN enables a “best of both worlds” approach to SD-WAN
There are a variety of mediums for WAN available to enterprises, and it is important that organizations weigh the pros and cons of a given solution. Cloud-based SD-WAN allows users to offload the complexity associated with appliance-based solutions by abstracting the underlying security and infrastructure away from the user.
Enterprise SDWaaS solutions also offer robust infrastructure that incorporates a variety of Internet transports (4G, DSL, MPLS, Cable, etc) and redundancy & failover features that are backed by SLAs to ensure you get the most out of your SD-WAN investment.
The real value add of cloud-based SD-WAN becomes apparent when you consider it is able to do all this and offload the complexity for the user, without taking away an enterprise’s control of their WAN. The takeaway here is: when all aspects of an SD-WAN solution are considered, the benefits of SDWaaS become clear, and simply put, it is the “happy medium” (pun intended) of SD-WAN.