SD-WAN passive WAN health measurement determines the health check measurements using session information that is captured on firewall policies that have Passive Health Check (
passive-wan-health-measurement) enabled. Passive measurements analyze session information that is gathered from various TCP sessions to determine the jitter, latency, and packet loss.
Using passive WAN health measurement reduces the amount of configuration required and decreases the traffic that is produced by health check monitor probes doing active measurements. Passive WAN health measurement analyzes real-life traffic; active WAN health measurement using a detection server might not reflect the real-life traffic.
By default, active WAN health measurement is enabled when a new health check is created. It can be changed to passive or prefer passive:
Health is measured using traffic, without probes. No link health monitor needs to be configured.