Software-defined networking (SDN) is an architecture that provides open networking wherever needed without the obvious connection of servers and devices.

On the other hand, software-defined wide-area networking (SD-WAN) is an SDN application applied to WAN connections. This allows branches to connect with the central office. It is a hardware-based networking system.

Multiprotocol label switching (MPLS) is more of a technique than a service that ensures efficient network flow between two destinations. It basically works like routers and is considered to be layer 2.5. It uses packet-forwarding technology for data forwarding. MPLS was invented before SDN or SD-WAN, but it’s expensive.

The main question is, how do all these networks work and what’s the difference between MPLS vs SDN-WAN vs SDN? You can find a detailed answer to this over here.