What is SD-WAN (Software-Defined Wide-Area Network)?

　　A software-defined wide-area network (SD-WAN), is a network that is abstracted from its hardware, creating a virtualized network overlay. Operators can remotely manage and quickly scale this overlay, which can span over large geographical distances. It is an application of software-defined networking (SDN).

　　An SD-WAN can connect several branch locations to a central hub office or cover multiple locations in a large campus such as a university campus. Because it is abstracted from hardware, it is more flexible and available than a standard WAN. It relies on four central components:

• 　　Edge connectivity abstraction

• 　　WAN virtualization

• 　　Centralized management

• 　　Elastic traffic management

　　SD-WAN Architecture

　　SD-WAN uses an abstracted architecture for its network. In an abstracted architecture, the network is divided into two parts: the control plane and the forwarding plane. This architecture moves the control plane to a centralized location like an organization’s headquarters. That way, the network can be managed remotely without the need for an on-premises IT crew.

　　There are three main components to an SD-WAN: The SD-WAN edge, the controller, and the orchestrator.

　　The SD-WAN edge is where the network endpoints reside. This can be a branch office, a remote data center, or cloud platform.

　　An SD-WAN Orchestrator is the virtualized manager for network, overseeing traffic and applying policy and protocol set by operators.

　　The SD-WAN Controller centralizes management, and enables operators to see the network through a single pane of glass, and set policy for the orchestrator to execute.

　　These components make up the basic structure of an SD-WAN. In addition, there are three main types of SD-WAN architecture: on-premises, cloud-enabled, and cloud-enabled with a backbone.

　　An On-premises SD-WAN is where the SD-WAN hardware resides on-site. Network operators can directly access and manage the network and the hardware it resides on, and it does not use the cloud for its connections. This makes making it ideal for sensitive information that cannot be sent over the internet.

　　Cloud-enabled SD-WAN  connect to a virtual cloud gateway over the internet, which makes the network more accessible, and provides better integration and performance with cloud-native applications.

　　Cloud-Enabled with Backbone SD-WANs give organizations an extra backup by connecting the network with a nearby point of presence (PoP), such as within a data center. It allows an SD-WAN to switch from public internet to a private connection, which adds an extra layer of security and consistency in case the connection is overwhelmed or fails.