What is a typical SD-WAN deployment for a branch with multiple underlays?

• A. A branch edge uses single tunnel over a single underlay.
• B. A branch edge uses multiple tunnels over different underlays (MPLS, Internet, cellular) with policy-driven path selection and fast failover for resilience.
• C. Tunnels are only for management traffic.
• D. Underlays are used only for backup.

Answer: (B)

In SD-WAN, handling a branch with multiple underlying transport networks means the branch edge connects to several underlays (like MPLS, Internet, and cellular) and creates separate tunnels over each one. Traffic is then steered by policies that consider application needs, performance metrics (latency, jitter, loss), and cost. If one transport starts performing poorly or fails, fast failover can quickly move traffic to another tunnel without manual intervention, maintaining service continuity. This multi-tunnel, multi-underlay approach provides resilience and optimal path selection, which is why the best deployment is the one that uses multiple tunnels over different underlays with policy-driven path selection and fast failover. Tunnels are used for data traffic, not just management, and underlays serve as the primary transport—not merely backups.