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Updated: Sep 4, 2020

Matt Johnson

Operations Director


A Common Question

I often hear when talking to customers is what is the difference between MPLS and SD-WAN?

To answer this we must first explain what is MPLS. Multi-Protocol Label Switching (MPLS) is a technology that allows the creation of private Wide Area Networks (WAN). It is typically deployed by telecommunication service providers or large Enterprises. In the case of Service Providers, this allows the ability to provision multiple autonomous customers on a common network infrastructure, typically on a national or global level. Large Enterprise’s typically uses MPLS to segregate multiple traffic types across national or global networks.

Key Features

Key Features of the MPLS standards are the ability to segregate traffic between networks and implement traffic engineering features like Quality of Service (QoS), this allows the network to recognise traffic flows that are sensitive to delay, like Voice or Video Conferencing and priorities them over less sensitive applications like email. Whilst also providing Network to Network Interfaces (NNI’s) which allow different MPLS networks to connect extending the end to end reach of a client network.

For most clients (end customers) of a Service Providers MPLS service a crude analogy would be that of a organisations internal mail system. Information can be exchanged with other staff or departments in other offices in other countries using an internal addressing structure (e.g Jane Smith, Finance, HQ). The envelope would be secured with other internal email in a larger container and transported via courier, where it would be delivered directly to the recipient. Taking the analogy a step further, external mail could only be posted out from the head office, so all mail is transported to the head office for onward routing.

Internal email can be thought of offering privacy, security, reliability and cost efficiency, and is probably a good solution if the bulk of the mail is destined for the head office. This is akin to a private network, nodes on the network can communicate with other nodes on the same organisations network, but not directly with nodes outside of the organisation. To achieve this communication must go via a central gateway. In the mail world, HQ’s post room. In the network world, a perimeter Firewall.

Sticking with the mail analogy, SD-WAN is like using the public postal service for internal and external communication. All mail sent between the organisations offices and 3rd parties is externally addressed and sent directly. Direct communication enables a faster and more efficient transportation and greater scalability. Potentially a better solution where communication is mainly external.

The Direct Route

SD-WAN is a technology developed to use the Internet as its transport medium. Devices (SD-WAN Edge) at each office create a web of secure tunnels across the Internet, between the organisation’s offices, other organisations and service providers to create direct, secure communication paths.  The SD-WAN Edge device can identify different application traffic flows and prioritise, route and secure them appropriately across these communications paths.

Is SD WAN right for your organisation?

Well, that depends on your IT strategy. 500 words and my somewhat “ropey” analogy is not enough to give you a definitive answer; however as organisations consume more services from the Cloud and have a greater number of employees accessing applications outside of the corporate network, then it’s certainly something they should be thinking about.


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