What is a typical SD-WAN deployment for a branch with a single underlay?

• A. A branch edge uses multiple underlays (MPLS, Internet, cellular) with policy-driven path selection and fast failover for resilience.
• B. A branch edge connects to the underlay (e.g., Internet) with a single tunnel to a central or cloud service, with limited active path diversity and simpler failover.
• C. A branch edge uses only cellular as underlay.
• D. A branch edge deploys without tunnels.

Answer: (B)

In SD-WAN, the number of underlays shapes resilience. When a branch has a single underlay, the branch edge typically establishes one secure tunnel over that underlay to a central site or cloud gateway. This setup provides connectivity and centralized policy, but it offers limited path diversity because there isn’t a second independent transport to route traffic through. If the underlay or the tunnel fails, there isn’t another underlay to switch to, so failover is simpler and less robust than in multi-underlay designs.

That’s why this scenario is described as a branch edge with a single tunnel to a central or cloud service, reflecting simpler, less diverse connectivity. The other options imply multiple underlays, exclusively cellular underlays, or no tunnels, which don’t fit the idea of a single underlay with a basic SD-WAN tunnel.