SD-WAN is an acronym for software-defined networking (SDN) in a wide area network (WAN). SD-WAN simplifies the management and operation of a WAN by decoupling the networking hardware from its control mechanism. This concept is similar to how software-defined networking implements virtualization technology to improve data center management and operation.[1]
A key application of SD-WAN is to allow companies to build higher-performance WANs using lower-cost and commercially available Internet access, enabling businesses to partially or wholly replace more expensive private WAN connection technologies such as MPLS
Features of SD-WANs include resilience, quality of service (QoS), security, and performance, with flexible deployment options; simplified administration and troubleshooting; and online traffic engineering.
Resilience
A resilient SD-WAN reduces network downtime. To be resilient, the technology must feature real time detection of outages and automatic switch over (fail over) to working links.
Quality of service[edit]
SD-WAN technology supports quality of service by having application level awareness, giving bandwidth priority to the most critical applications. This may include dynamic path selection, sending an application on a faster link, or even splitting an application between two paths to improve performance by delivering it faster.
Security
SD-WAN communication is usually secured using IPsec, a staple of WAN security.
Application optimization
SD-WANs can improve application delivery using caching, storing recently accessed information in memory to speed future access.
Deployment options
Most SD-WAN products are available as pre-configured appliances, placed at the network edge in data centers, branch offices and other remote locations. There are also virtual appliances that can work on existing network hardware, or the appliance can be deployed as a virtual appliance on the cloud in environments such as Amazon Web Services (AWS), Unified Communications as a service (UCaaS) or as Software as a Service (SaaS).This allows enterprises to benefit from SD-WAN services as they migrate application delivery from corporate servers to cloud based services such as Salesforce.com and Google apps.
Administration and troubleshooting
As with network equipment in general, GUIs may be preferred to command line interface (CLI) methods of configuration and control. Other beneficial administrative features include automatic path selection, the ability to centrally configure each end appliance by pushing configuration changes out, and even a true software defined networking approach that lets all appliances and virtual appliances be configured centrally based on application needs rather than underlying hardware.
Online traffic engineering
With a global view of network status, a controller that manages SD-WAN can perform careful and adaptive traffic engineering by assigning new transfer requests according to current usage of resources (links). For example, this can be achieved by performing central calculation of transmission rates at the controller and rate-limiting at the senders (end-points) according to such rates
