Underlay networks can’t be overlooked when deploying SD-WAN. It is often forgotten that the SD-WAN overlay will inherit the attributes of the underlay network. Low-latency underlay networks ensure that SD-WAN will benefit from higher performance with less packet loss and jitter.
The SD-WAN market is projected to generate billions of dollars of revenue over the next few years, with Research and Markets estimating the overall global SD-WAN market to reach a staggering $7.8 billion by 2027.
The main drivers of this market growth are enterprises seeking easier management of WAN connectivity to improve application performance and user experience, coupled with multi-cloud and hybrid cloud adoption stitched together in a secure fabric.
Traditional underlay services like MPLS are falling behind the needs of today’s cloud-first enterprises. While MPLS can provide high-performance and low-latency connectivity, this comes at the cost of visibility, flexibility and scalability.
This makes the interplay between underlay and overlay network services absolutely critical for maximising the value of SD-WAN.
In order for enterprises to reap the full benefits of SD-WAN, a high-performance networking solution is vital. They must consider different underlay options for SD-WAN such as Dedicated Internet Access (DIA), to ensure the success of their SD-WAN and cloud deployments with higher levels of efficiency.
Understanding SD-WAN
MEF defines an SD-WAN service as “a service that provides a Subscriber with a virtual overlay network that enables application-aware, policy-driven, and orchestrated connectivity between SD-WAN User Network Interfaces (UNIs). It also provides the logical construct of a L3 Virtual Private Routed Network for the Subscriber that conveys IP Packets between Subscriber sites.”
MEF also created an important certification, MEF 3.0, to enable service and technology providers to validate that their SD-WAN services conform to the MEF 70 standard. MEF 3.0 SD-WAN services can take advantage of multiple Underlay Connectivity Services to deliver differentiated service capabilities rather than connectivity services based on a single transport facility.
Importantly, MEF has defined Optical Transport, Carrier Ethernet and IP services in a suite of standards, and these service definitions are an important basis for Underlay Connectivity Services. In other words, MEF 3.0 SD-WAN services are defined as overlay services, and MEF 3.0 Optical Transport, Carrier Ethernet and IP services can be used as Underlay Connectivity Services to support the SD-WAN overlay service.
SD-WAN offers some incredible link remediation capabilities that really showcase the power of what this technology can offer. Forward error correction, revertible failover, packet duplication, dynamic path optimisation – the list goes on and on with options the managed SD-WAN service provider can deploy to mitigate poor performing, best effort underlay connectivity services.
As mentioned above, one of the key components that build on this global Services framework is the Underlay Connectivity Service. MEF is taking Service Operation, Administration and Management (SOAM) and Service Acceptance Testing (SAT) very seriously. The performance of the Underlay Connectivity Service and the subsequent impact on SD-WAN’s performance have resulted in standards been explored, like MEF 66 and MEF 61.1
An underlay with high latency will mean that the SD-WAN overlay will inherit the attributes of the underlay and in turn have a high latency. The same is true with packet loss and jitter, and this is where SD-WAN’s link remediation can only go so far.
One of the top drivers for enterprises utilising SD-WAN is to achieve better WAN and application performance regardless of the device location and access technology type. A poor underlay will ultimately result in in a poor Application Quality of Experience (AppQoE).
With SD-WAN now in a mature state and past the hype cycle of just cost savings, a lot more focus must be given in the design and selection of the Underlay Connectivity Service to ensure SD-WAN can drive the application performance and user experience it was intended for. Site availability is taking a back seat in favour of key network metrics with the net result and lens on user experience.
SD-WAN and the cloud
With cloud adoption accelerating, getting an underlay service that has predictable metrics around latency, jitter, packet loss and availability is becoming a key component to the fabric of next generation SD-WAN design and deployments.
This demand for a reliable, low latency and low packet loss route to different cloud providers is one of the key drivers for SD-WAN to deliver on this mandate. For over 20 years, MPLS has a proven track record of delivering on these metrics in a predictable manner, so how do you go about ensuring Internet access technologies can deliver a similar service to MPLS, while leveraging the many advantages a next generation SD-WAN can provide?
Traditional routing protocols form adjacencies and distribute link state information with a limited and static view of the entire path an application will need to traverse, both in the transmit and receive direction. This hop-by-hop view does not provide the full picture for key elements in making application-aware routing decisions and delivering on the AppQoE, although segment routing does address some of these legacy setup drawbacks.
Software-defined insights
To move forward with an intelligent network, enterprises must seek software-defined options that can provide superior insights than legacy underlay services such as MPLS.
They need to find a provider that can offer a next generation software-defined network (SDN) backbone that leverages Artificial Intelligence (AI) to provide a full map and state of the entire topology of its global network. It should provide a key focus on application-level performance and visibility, as well as ensuring the fastest route to the desired content or service.
The SDN should steer application traffic autonomously to ensure service levels are maintained throughout the process of connecting the user to the required service. These powerful and intelligent networks should also provide an enhanced service level offering of Dedicated Internet Access (DIA).
Moving forward with DIA
DIA specifically responds to enterprises’ requirements for an underlay that performs similar or better than MPLS, whilst providing the required diversity DIA brings natively.
Purpose-built Service Level Agreements for DIA can help to meet site availability, latency and packet loss requirements. Whether the enterprise’s requirement is Site to Site, Site to Cloud, Site to CDN or Site to Internet Exchange, the right DIA service will provide predictable network thresholds to support these.
SD-WAN brings so many exciting options to the table – enterprises just need to ensure the underlay network supports the outcomes that they want for their overlay SD-WAN services.
With a software-defined approach to the WAN, paired with efficient and high-performance DIA underlay, enterprises can transform their network with a solid SD-WAN solution that is ready to meet their connectivity needs both now and into the future.
