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 visualized 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. 

The Benefits of SD-WAN

The global SD-WAN market is predicted to swell to $5.25 Billion in 2023, according to an IDC forecast in July 2019, as more businesses embrace the benefits of a virtualized network.

The key benefits include:

  • Increased bandwidth at a lower cost since the network traffic can be provisioned for optimal speeds and throttle low-priority applications.

  • Centralized management across branch networks through a simple management console, which reduces the need for manual configuration and on-site IT staff

  • Full visibility into the network, as the controller gives operators a holistic view of the network.

  • More options for connection type and vendor selection, since the network can reside on COTS hardware and use both private and public connections to route its traffic.

 

SD-WAN vs. MPLS

  • Before SD-WAN came along, there was Multiprotocol Label Switching (MPLS), a protocol for efficient network traffic flow between two or more locations. MPLS operates similarly to switches and routers, sitting between layers 2 and 3.

  • (MPLS is sometimes considered layer 2.5.) It uses packet-forwarding technology and labels to make data forwarding decisions. The label is imposed between the layer 2 (data link) and layer 3 (network) headers.

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