Which mechanism does Cisco SD‑WAN implement for data‑plane resiliency?

BFD (Bidirectional Forwarding Detection) is a lightweight protocol used to quickly detect failures in the data plane between two forwarding engines. In Cisco SD-WAN, BFD sessions are established between WAN Edge routers over IPsec tunnels to monitor the liveness of these tunnels and the data plane path. If BFD detects a failure, it rapidly notifies the routing protocol (OMP) to converge and reroute traffic, thus ensuring data-plane resiliency. Multiple vBond orchestrators provide control plane resiliency for initial device onboarding, not data plane. Establishing affinity between vSmart controllers and WAN Edge routers is for control plane scalability and redundancy, not direct data plane failure detection. OMP (Overlay Management Protocol) is the control plane protocol responsible for advertising routes and policies, but it relies on mechanisms like BFD for rapid data plane failure detection.