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Blog: SD-WAN vs MPLS

21 April 2020

If you are involved in Enterprise Networking, you will doubtless be up to speed with SD-WAN, and may be actively considering an SD-WAN solution. You may have seen it argued that SD-WAN eliminates the need for MPLS, and therefore cost and complexity from the network. From one perspective that is correct, but more realistically there is a place for both SD-WAN and MPLS in a modern Enterprise Network for at least for the next few years.  

Let’s set some context. Back in the day, Multiprotocol Label Switching (MPLS), was a rather revolutionary WAN technology, as it enabled service providers to build network infrastructure that could provide enterprise customers with the option to  interconnect their datacentres and remote sites more flexibly than before, through enabling ‘enterprise virtual private networks’. MPLS didn’t require any additional security because the traffic was still being carried across a private network infrastructure. It was engineered to support data between sites, including voice and video files and critical applications.

So, 20 years ago MPLS represented “the wave of the future”. However, consider how our business dependency on the internet and use of apps has evolved and changed in that time. The ability for people to work and interconnect from anywhere with anyone or any application has created an ever-growing demand for content, bandwidth, and performance. Even the recent forced pivot by companies to full remote and home based working models is a significant change and increases the need for enterprise WAN environments to be more  flexible whilst maintaining security and facilitating access to enterprise data, applications and resources from anywhere, and has, by and large, not led to seriously degraded internet performance. Our business applications increasingly use the cloud by default, and video calls have quickly become our new normal. These changed patterns will drive the demand for security and remote collaboration capacity even more.

MPLS was a major and significant step forward for Enterprise WAN connectivity, but on its own it can’t deliver the required levels of flexibility, resilience, security and, speed of deployment that an SD-WAN solution can.

We see six main advantages to evolving to an SD-WAN solution:

Connectivity costs: Despite the end-to-end QoS, the biggest downside to MPLS is really the circuit cost. If your business needs 100Mbps+ bandwidth, monthly circuit costs can be prohibitive, despite the benefits increased bandwidth might bring.

The Software defined landscape: SD-WAN was born out of the ‘software defined network’ revolution. This redefined approach to networking logically separates control plane functions (network traffic routed paths) from the data plane functions (physical network inter-links). SD-WAN creates a centrally managed and, most importantly, encrypted virtual network overlay. This enables secure virtual traffic paths between sites and data locations, connecting enterprise network users to applications and data via the most optimal path.

Agility: While MPLS only offers one static network connection, SD-WAN offers dynamic path selection, fluidity is essential as, for example, you may want to route internet browsing traffic over internet links and critical voice traffic over MPLS. SD- WAN solutions achieve this by having a centralised view not just of the physical network topology interconnections, but by being aware of the network topology capabilities through measuring link capacity, speed, monitoring latency and jitter across physical links. SD-WAN solutions create an intelligent overlay that aligns closer to the needs of the business, delivering security and efficiency via a central ‘single pane of glass’ management system.

SD-WAN delivers immediate advantages over MPLS through intelligent application and SaaS cloud destination aware routing of:

  • ‘Hybrid datalink layer’ - a combination of private (MPLS, leased line) circuits and public (internet based) links
  • Pure Public (internet access) links
Resilience:  SD-WAN solutions can recognise key Enterprise applications, SaaS traffic flows and other higher-level protocols to then make intelligent routing decisions across the overlay paths for SaaS cloud destinations, application types and traffic flow. This application and SaaS cloud destination awareness enables SD-WAN solutions to always deliver the best possible Quality of Experience (QoE) for network users. SD-WAN deployed in a WAN with hybrid or multiple internet VPN links intelligently routes around failures and or partially degraded network links to find the path that provides the best QoE.

Direct Internet Access: SD-WAN provides a centrally managed solution with the ability to enable access to SaaS and Cloud applications from any location without backhauling or ‘tromboning’ all traffic via the corporate Data Centre. Traffic path encryption enables traffic to flow securely over potentially lower cost and higher bandwidth broadband internet datalink layer links. SD-WAN can traverse any type of datalink connection including MPLS, Internet and 4G LTE. This creates a hybrid WAN environment by enabling aggregation of connections, facilitating fast speed at a low cost via inexpensive broadband internet access, or DSL lines. Finally, with MPLS many networks are locked in to their service provider – the perceived workload of switching sites has led to a “grin and bear” it mentality. With SD-WAN, companies aren’t captive – they can easily switch ISP at any site.

Increasing uptime: By aggregating multiple Internet and WAN connections known as a ‘Hybrid network’ topology, SD-WAN delivers seamless circuit redundancy. MPLS providers may offer a failover to a secondary Internet connection but it’s often not instantaneous, and there is no QoE.

Not all remote locations can justify the high cost of an MPLS circuit or worse still, they’re not serviceable by their MPLS provider. In the past this was accepted as a given and remote sites typically suffered reduced performance. However, SD-WAN is provider-agnostic and delivers the same benefits irrespective of the underlying ISP.

Download the SD-WAN Buyer’s Guide >