What is SD-WAN?
SD-WAN uses software control and central policy to manage multiple wide-area network connections.
How it works and where it is used
Branches may combine fiber, internet and other links, selecting paths based on application needs. Latency, loss and cost influence decisions. Software-defined control does not remove physical dependency: a poor last mile or provider failure still matters.
Limits, safety and selection criteria
Encrypted tunnels, identity and access rules belong in the design; a product label is not a security guarantee. Plan for controller outages, software defects and policy errors. Measure real application traffic during migration. A branch can send video calls over a low-latency link and bulk backups over a cheaper one. Failover should consider loss and application quality, not just whether a line reports connected. A backup circuit sharing the same street cabinet or operator remains vulnerable to a common failure. Centralized control simplifies policy but one bad rule can affect all branches. Pilot deployments and measured rollback are important. Encryption and traffic steering also need testing against real user applications, not merely synthetic pings.