Which protocol measures loss, latency, jitter, and liveliness between WAN Edge router peers?

BFD (Bidirectional Forwarding Detection) is a lightweight, low-overhead protocol used to detect failures in the forwarding path between two routers. It measures loss, latency, and jitter, and verifies the liveliness of the connection, making it crucial for fast fault detection in SD-WAN environments. OMP (Overlay Management Protocol) is the routing protocol for the SD-WAN overlay, responsible for advertising routes and policies, but not for measuring link quality. NetFlow is used for collecting IP traffic flow information, primarily for monitoring and analysis, not for active link health measurement. IP SLA (IP Service Level Agreement) is a Cisco feature that can measure network performance, but BFD is specifically designed for rapid, lightweight fault detection between peers, making it the more accurate answer in the context of continuous link monitoring in SD-WAN.