Comprehensive and Detailed Explanation

Prisma SD-WAN utilizes a sophisticated decision engine forApplication-Based Path Selectionthat goes beyond simple failover. When configuring a Path Policy, the administrator defines "Active" paths and a "Path Quality Profile" (SLA).

SLA Compliance (The Filter):First, the system filters the available paths based on the Path Quality Profile. In this scenario, both ISP-A and ISP-B have 40ms latency against a 150ms threshold. Both are "green" or compliant paths.

Selection Criteria (The Tie-Breaker):When multiple paths are configured as "Active" and all meet the performance SLA, the ION device aims to optimize the overall user experience and network utilization. The default behavior for load balancing across healthy, compliant active paths is to select the path with thehighest available bandwidth capacity.

By steering new flows to the link with the most "headroom" (available Mbps), the system prevents the saturation of a smaller link (e.g., a 20Mbps DSL line) while a larger link (e.g., 1Gbps Fiber) sits underutilized. This maximizes the aggregate throughput for the site. While latency is thequalifier, bandwidth availability is often theselectorfor compliant paths. Note that if the application was defined as "Real-Time" and configured for packet duplication, behavior would differ, but for standard traffic, capacity-based distribution is the standard active/active logic.