Which SD-WAN model?

No company can ignore the speed with which SD-WAN is gaining traction or the scale of innovation globally. With the market on the cusp of widespread adoption, Nick Sacke, Head of IoT and Products at Comms365, explores the challenges that businesses and IT providers are facing.

With organisations needing to determine how and why they will deploy SD-WAN, one of the challenges facing service providers, multi-site businesses and IT departments is the ongoing role of MPLS technology, recognising that legacy WAN contracts may still in place.

The opportunity to implement a hybrid WAN solution model incorporating both MPLS and SD-WAN provides the opportunity for organisations to harness the best attributes of both technologies and begin a phased migration process from MPLS to SD-WAN now, as Nick Sacke, Head IoT and Products, Comms365 explains.


In a cloud dominated user environment, the quality and reliability of the WAN to deliver application performance has become an essential component of IT infrastructure design. The current consensus is that traditional MPLS networks struggle with the volume of Internet-based cloud traffic, the diversity of routing locations (applications are delivered from multiple clouds, not a single datacentre), and ensuring application performance across both MPLS and Internet-bearing services.

The impact of this is an increase in the number of customers evaluating and requesting SD-WAN solutions from their service providers. Indeed, it would be hard to find an organisation today taking the decision to go for traditional MPLS without considering the SD-WAN alternative.

The way in which organisations decide to deploy SD-WAN will be key. Right now in the UK it is the Managed SD-WAN service model that dominates the market, as experienced MSPs can rapidly deploy the solution with demonstrable high performance and multiple built-in capabilities from day one, meaning that organisations can reap the benefits almost immediately.

In contrast to the Managed Service where every aspect of the service and all changes to the parameters of that service are undertaken by the MSP, the alternative deployment model is SD-WAN as a Service. This approach, which has yet to become widely available in the UK, is gaining significant interest in North America. This software only model provides a multi-tenanted infrastructure set up that enables companies to rapidly connect sites while also providing the IT Manager with the tools to monitor, manage and change service parameters as required.

A Hybrid Approach

SD-WAN has the potential to be a replacement for MPLS, but this is not necessarily the right option for every organisation. For a UK multi-site operation, many of the sites could still be in contract with months or years still remaining – so a replacement to SD-WAN would be commercially challenging.

An alternative approach to consider is to combine MPLS and SD-WAN together as a hybrid approach in order to augment capacity, enable rapid expansion, increase control to IT managers and not having to increase the overall MPLS contract term for the addition of a few sites – without a huge financial outlay. By adopting such an approach, the case for complete replacement of MPLS can then be considered longer term without penalty.

Differentiating between MSPs will be based on issues such as access to a diversity of connectivity options and quality of service – for example, does the MSP support the need for agility and flexibility, as well as future proofing, by offering a network agnostic SD-WAN?

SLAs will be key and, over time, the managed SD-WAN services on offer will undoubtedly become ever more sophisticated as MSPs look to exploit the intelligence within the SD-WAN technology. Traditional response times are no longer good enough in application centric organisations, so it is important to determine whether or not an MSP is leveraging the software only nature of SD-WANs to overhaul its own support operation.

Cost Consideration

In terms of service model, the cost differential between a Managed MPLS and a Managed SD-WAN service are negligible. The SD-WAN as a Service model is significantly cheaper – but it will require additional internal resource, so the operational cost comparison will depend upon the existing IT skill base and need to add heads to manage the network.

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David Dungay

Editor - Comms Business Magazine