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Don’t Overlook the Underlay: Ensuring SD-WAN Success with Intelligent Enterprise Networking

Geoff Dornan, Group Chief Technical Officer at CMC Networks
Geoff Dornan, Group Chief Technical Officer at CMC Networks

The interplay between the underlay and overlay network is crucial for elevating the value of SD-WAN.

Evolving cloud demands on a global scale are pushing enterprises to rethink their networking strategies. Legacy networks can no longer keep up with the needs of today’s cloud-first enterprises,

The global software-defined wide-area network (SD-WAN) market is projected to grow at a rapid CAGR of over 30% between 2022 and 2027, according to Expert Market Research.

Alongside the deployment of new technologies like multi-cloud and hybrid cloud, further key drivers of this market growth are enterprises seeking easier management of their WAN connectivity, as well as seeking to improve user experience and application performance.

Traditional underlay services like MPLS can provide high-performance and low-latency connectivity, however offer little visibility, flexibility and scalability.

An underlay network cannot be overlooked when deploying SD-WAN, since the SD-WAN overlay will inherit the attributes of the underlay network. SD-WAN can benefit from higher performance with less packet loss and jitter with a low-latency underlay network.

The interplay between the underlay and overlay network is crucial for elevating the value of SD-WAN.

Enterprises can reap the benefits of SD-WAN and ensure the success of their cloud deployments by considering different underlay options like Dedicated Internet Access (DIA).

Defining SD-WAN

MEF, a non-profit industry forum that develops standards, certifications and APIs, defines SD-WAN 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 3.0 is an important certification created by MEF, which enables service and technology providers to validate that their SD-WAN works to the MEF 70 standard. MEF 3.0 SD-WAN services can utilise multiple Underlay Connectivity Services to deliver differentiated service capabilities instead of basing the connectivity services on a single transport facility.

MEF has defined Carrier Ethernet, IP services and Optical Transport in a suite of standards, which form an important basis for Underlay Connectivity Services. This means that MEF 3.0 SD-WAN services are defined as overlay services, and MEF 3.0 Carrier Ethernet, IP services and Optical Transport can be used as Underlay Connectivity Services.

SD-WAN can offer some great link remediation capabilities that demonstrate the power of this technology, including:

  • Forward Error Correction
  • Revertible Failover
  • Pack Duplication
  • Dynamic Path Optimisation

The list goes on, with many options the managed SD-WAN service provider can deploy to mitigate poor performing underlay connectivity services.

Enterprises that utilise SD-WAN want to achieve better WAN and application performance regardless of the device location and access technology type. A poor underlay will result in poor Application Quality of Experience (AppQoE).

SD-WAN is now in a mature state and past the pure cost-saving stage, which means a lot more focus must go into the design and selection of the Underlay Connectivity Service to ensure SD-WAN can drive the application performance and user experience it is capable of.

Accelerated Cloud Adoption

Widespread cloud adoption is shaping the next generation of SD-WAN design and deployments, which require an underlay that can provide predictable metrics around:

  • Latency
  • Jitter
  • Packet loss
  • Availability

Enterprises are looking for a reliable, low latency and low packet loss route to cloud providers that can meet their changing demands. For over 20 years, MPLS delivered on these metrics in a predictable manner. However, traditional routing protocols form adjacencies and distribute link state information with a static and limited view of the entire path an application will need to follow.

This does not provide the full picture for intelligent decision-making, application-aware routing and delivering on AppQoE, however segment routing could address some of these legacy setup disadvantages.

Enterprises are now seeking more cost-efficient and flexible Internet access technologies that can deliver a similar service to MPLS whilst leveraging the benefits of next generation SD-WAN.

Superior Software-Defined Services

An intelligent, software-defined network (SDN) can help enterprises to move forward with better insights than a legacy underlay service like MPLS.

By finding a provider that offers a next generation SDN backbone utilising artificial intelligence (AI), they can map out the entire topology of their global network. The provider should have key focus on the performance and visibility at application level, while providing the quickest route to the required content or service.

The SDN should guide application traffic autonomously to ensure service level agreements (SLAs) are maintained when connecting the user to the right service. These types of intelligent networks should also provide Dedicated Internet Access (DIA) offerings with defined SLAs.

Future-Proofing SD-WAN with DIA

DIA has the power to meet enterprises’ requirements for an underlay that can perform similar or better than MPLS, while also providing diversity.

Site availability, latency and packet loss requirements can be met with purpose-built SLAs for DIA, to guarantee a superior connectivity service for enterprises. The right DIA service will provide a network that is predictable and can support the necessary thresholds for the enterprise’s requirement, whether that is Site to Site, Site to Cloud, Site to CDN or Site to Internet Exchange.

Enterprises can transform and future-proof their networks by pairing their SD-WAN overlay with a high performing, efficient DIA underlay. With the right underlay network, SD-WAN can bring many exciting opportunities for enterprises – they just need to ensure it can support the outcomes that they are looking for.

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