Which tunneling encapsulation is commonly used in SD-WAN overlays for non-IPsec topologies or multi-tunnel setups?

• A. GRE is the only encapsulation used in SD-WAN overlays.
• B. VXLAN is the standard for all overlays.
• C. IPsec is commonly used; GRE or VXLAN may be used for non-IPsec overlays or multi-tunnel topologies when needed.
• D. UDP encapsulation is used exclusively.

Answer: (C)

In SD-WAN overlays, secure transport is typically provided by IPsec, which handles encryption and authentication for traffic across the Internet. But when you need to carry non-IP payloads or create multiple parallel tunnels between sites, an additional tunneling method like GRE or VXLAN is used to wrap the traffic inside the overlay. This combination lets the network carry diverse types of traffic and support multi-tunnel topologies while still benefiting from IPsec security. So using IPsec as the common foundation, with GRE or VXLAN chosen for non-IP or multi-tunnel scenarios, matches how SD-WAN overlays are often deployed.