New Kid on the Block

April 8, 2019 Claranet Limited

SD-WAN technology has been talked about for some time and has now arrived in the UK with a bang, and network providers are all in the process of reviewing, packaging and launching services. 

What does this have to do with voice and Unified Communication (UC) services, however? One of the claims providers of SD-WAN has been making is that it can improve the quality and reliability of IP voice and UC, even over poor connections.

In this blog, we break down the SD-WAN proposition and see how this claim stands up.

What is SD-WAN?

SD-WAN is often described as ‘cloud networking’ or ‘cloud-ready networking’. At a practical level, it involves putting a new box on site and plugging your internet connection into it. These dedicated boxes are a combined application and firewall, and perform a useful trick called ‘Deep Packet Inspection’.

Deep Packet Inspection (DPI) allows the box to interrogate all the traffic going over your connection and identify what applications are using it and allows a customer to control the amount of bandwidth those applications consume from what’s available. Where multiple connections are used, either in one site or in several, they can be controlled remotely, and different applications prioritised in some locations, or in the event where one line goes down, traffic seamlessly shifted to another.

It’s worth pointing out here that SD-WAN is not a standardised or regulated model, but is deployed in different ways from different vendors.

The platform is managed via an online dashboard that presents a range of metrics and reports from the on-premise boxes, which can be run over time to reveal trends in application and data usage from a site’s users – finding out, for example, that key application traffic slows down at lunchtime as people watch YouTube or access social media.

How does SD-WAN help with Voice and UC?

A lot of the vendor’s marketing messaging around SD-WAN touches on how it can help make voice and Unifed Communications (UC) better - but it’s not quite as it appears.

SD-WAN is a technology originated in the US and Asia and developed with their markets and interests up front. In the US and Asia, MPLS connectivity is more expensive than public internet access. SD-WAN provides a lot of the capability of a private MPLS network in terms of control of applications over the data connection but works over public internet lines. It uses DPI in place of Quality of Service (QoS) or packet marking.

Also, in these markets, there are greater reliability problems with physical connectivity in some areas, so being able to seamlessly switch traffic and change profiles of usage across connections is really useful to business continuity.

So, in those markets, SD-WAN is great for giving granular control of bandwidth usage to a customer over public internet lines, allowing them to prioritise and protect critical application traffic like voice, without needing the expensive MPLS connection.

In the UK however, our market is different. MPLS network access and public internet access are often priced similarly, and if you shop around to have the right provider, there is very little cost difference between internet and MPLS connections. The key variable is usually the amount of bandwidth and the nature of the underlying physical connection, rather than the network it is connecting to.

Equally, UK standards of connectivity uptime are higher, so the ability to switch traffic across connections is less critical. SD-WAN’s load balancing capability (i.e. the ability to choose which connection handles which applications) is still useful, however.

MPLS networks have long been preferred for voice traffic for good reason – it allows voice traffic to be fully protected from other uses via QoS and packet marking, and where voice is being provided via a centralized PBX within the network or delivered over the MPLS network, it maintains call quality for all voice users.

However, the market is moving and voice quality expectations are becoming less critical for many users, and for some, they are now consuming entirely ‘over the top’ (cloud-based) telephony or UC services like BlueJeans or Zoom for conferencing that are not designed to operate in an MPLS environment.

The same is true of other business-critical applications such as Email, CRM, or accounting/invoicing services which are moving at pace to publicly hosted cloud platforms and therefore do not benefit from MPLS in the same way that dedicated or on-premise applications do.

In this new environment, SD-WAN is a useful tool for providing secured access to business applications, and protecting access to the new cloud-based voice and UC applications for users and user groups who do not need full on MPLS voice, such as users of Claranet’s new Teams Voice service, based on the Office365 Teams application.

Does SD-WAN replace MPLS?

There is still a place for MPLS in the delivery of voice and UC – teams who are heavily reliant on voice quality such as call centre agents, outbound sales, or customer service teams need to know that their calls are getting through and are intelligible.

The emergence of SD-WAN for UK businesses adds a useful capability to the enterprise network toolkit, for securing access for new and remote sites where MPLS may not be worthwhile, and helping them utilise cloud-based voice and UC applications.

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