An enterprise plans to evolve from a traditional WAN network to a software-defined WAN network. The existing devices have limited capability when it comes to virtualization. As the migration is…

Deploying controllers first establishes the SD-WAN orchestration and management plane that all edge devices depend on for policy and tunnel establishment. Deploying SD-WAN edge routers in the data center next creates the hub termination point before any branch is migrated, ensuring branches always have a destination to connect to. Migrating branch sites last means each branch is cutover into an already-operational overlay, preventing any traffic impact to enterprise applications.

Migrating data center WAN routers before SD-WAN edge routers are in place removes the existing hub without a replacement overlay ready, causing a traffic outage for all branches simultaneously.

Migrating branch sites before controllers or data center infrastructure are deployed leaves branches with no SD-WAN control plane or overlay hub, resulting in immediate connectivity loss.

Deploying SD-WAN edge routers before controllers means the edge routers cannot register or receive policies, rendering the edge deployment non-functional until controllers are later added.