What is SD-WAN?

SD-WAN is an overlay network used to build encrypted tunnels over existing Internet circuits (public or private)

Deployments yield a secure cloud network capable of remote orchestration, comprehensive QoS, and unlimited scalability

Overlay Networks isolate network operations from the underlying infrastructure using packet encapsulation. Data is encapsulated before transmission, the protocol for which is determined by the type of overlay being utilized, and it is then unwrapped ("de-encapsulated") upon reaching its destination. SDN is the latest in a series of popular overlay technologies; previous protocols developed for overlay networking include VPNs, VLANs, VoIP, and other virtualized services.

Through an SD-WAN overlay, administrators can implement a wide variety of network functions and services to their entire organization from a centralized management plane over the public Internet.

SD-WAN offers "MPLS-like" network segregation and QoS at a significantly cheaper price point

Instead of leveraging private network segments obtained from a carrier, SD-WAN can be deployed over public Internet connections

Multi-Protocol Label Switching (MPLS) networks secure total control over data traffic by tagging packets with labels that spell out how to handle said packets. These labels simplify how packets travel over the network; most traffic can be forwarded at the switching/ data link level (layer 2 of the OSI), using labels, instead of having to reference IP header information that would inform more involved traffic-shaping decisions processed at the routing/ network level (layer 3 of the OSI).

MPLS labels packets to establish different classes of service in the network, which can then be prioritized to efficiently ensure quality of service (QoS).

SD-WAN refers to a Wide Area Network (WAN) that uses Software Defined Networking (SDN)

SDN separates the control plane from the data plane

Routers (and switches) enable the flow of packets over a network. When processing traffic, there are three distinct planes of operation:

Control Plane: Establishes the "how" for networked communication. Transfer and Internet Protocols are the backbone for packet control, determining where traffic is sent. Control plane responsibilities include system configuration, management, and exchange of routing information between networking devices (neighbor tables, link state databases, and the like) to dynamically optimize throughput.

Data Plane: Also considered the Forwarding Plane, Carrier Plane, or the User Plane, it leverages the logic established by the control plane to transmit and receive packets. Quality of Service (QoS), filtering, queuing, policing, and other traffic-shaping behavior is handled on this plane (because this is where the traffic is). Loosely, it contains the "what" for networked communication.

Management Plane: Configures (or monitors) the control plane, including command line interfaces (CLIs), graphical user interfaces (GUIs) and any other platform capable of pushing changes to system settings.

SDN abstracts the hardware-bound control plane, removing the burden from network gateways (i.e. routers) and transferring it to a centralized software-based controller. SDN-enabled routers (commonly referred to as "nodes") no longer need to run control protocols individually, instead outsourcing control plane processes to be defined by software for the entire network.