Which protocol is used to measure loss, latency, jitter, and liveness of the tunnel between WAN Edge router peers?

OMP (Overlay Management Protocol) is the control plane protocol used to distribute routes and policies between vSmart and vEdge routers - it does not measure tunnel quality metrics.

NetFlow is a traffic flow export protocol used for visibility and analytics, not for measuring tunnel loss, latency, or jitter.

Cisco SD-WAN runs BFD hello packets across each IPsec tunnel between vEdge peers to measure real-time path quality metrics including loss, latency, jitter, and liveness. This data is used by the vSmart controller and application-aware routing policies to make intelligent path selection decisions. BFD runs natively on each WAN Edge router and is the primary tunnel health monitoring mechanism in the SD-WAN architecture.

IP SLA can measure similar network metrics but is a separate Cisco feature not used natively between vEdge peers for SD-WAN tunnel quality monitoring.