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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.

Comprehensive and Detailed Explanation

Prisma SD-WAN (formerly CloudGenix) defines three distinctOperational Modesfor a branch site, which determine how the ION device processes traffic and interacts with the network.

Analytics Mode (Monitor):In this mode, the ION device is typically deployed inline or in a "promiscuous" monitor state to gain visibility into network traffic without actively enforcing path selection policies.1It "learns" applications, bandwidth usage, and network characteristics (auditing) but does not steer traffic or block flows.2This is often used during Proof of Concepts (POVs) or the initial "burn-in" phase of a deployment to generate reports without risking network disruption.

Control Mode:This is the full production state. In Control Mode, the ION device actively enforcesPath Policies,QoS Policies, andSecurity Policies. It builds Secure Fabric VPN tunnels, steers traffic based on application SLAs (e.g., sending voice over MPLS and bulk data over Broadband), and handles failover events.3This is the required mode for a fully functional SD-WAN site.

Disabled Mode:This mode effectively shuts down the site's SD-WAN functionality from the controller's perspective. It is an administrative state used when a site is being decommissioned, provisioned but not yet live, or isolated for troubleshooting. In this state, the device does not participate in the fabric.

Comprehensive and Detailed Explanation

In Prisma SD-WAN routing configuration, theScopesetting on a BGP Peer (or a Static Route) controls the redistribution logic for the prefixes learned from that source.

Local Scope:If a BGP peer is configured with "Local" scope, the ION device will install the learned routes into itslocalrouting table for its own reachability, but it willnotadvertise (redistribute) these routes to other ION devices via the Secure Fabric. They remain local to the site.

Global Scope:To advertise reachability to the rest of the network, the BGP peer must be configured with"Global"scope. This tells the ION that any prefixes learned from this specific neighbor (e.g., the DC Core Switch) should be propagated across the SD-WAN overlay to remote branches. This is the critical setting for enabling branch-to-DC communication for applications hosted behind that BGP peer. Without "Global" scope, the branches would never learn the routes to the data center subnets.

Comprehensive and Detailed Explanation

In Prisma SD-WAN (CloudGenix),Path Policiescontrol how application traffic is steered across WAN links. To ensure that traffic is automatically shifted from a saturated circuit to another circuit with available bandwidth, both circuits must be configured asActive Pathswithin the policy rule.

When multiple paths are designated as "Active," the ION device treats them as a shared pool of available resources. The system continuously monitors the bandwidth utilization (capacity) and health (latency, jitter, loss) of all active links. If "Circuit A" (500 Mbps) becomes saturated or approaches its defined bandwidth limit, the ION's intelligent scheduler will automatically direct new application flows to "Circuit B" (100 Mbps) because it is a valid, healthy Active path with available capacity. This achieves effective load balancing and bandwidth aggregation.

In contrast, configuring "Circuit B" as aBackup Path(Option A or B) creates a strict priority relationship. Traffic would only move to the Backup path if the Active path completely failed or violated its configured SLA (Path Quality Profile) significantly enough to be considered "down." Mere bandwidth saturation might not trigger an SLA failure immediately, potentially leading to dropped packets on the saturated link while the backup link remains idle. Therefore, placingBoth circuits under active pathis the correct configuration for dynamic capacity management.

Comprehensive and Detailed Explanation

In a Prisma SD-WAN High Availability (HA) deployment, theHA Control Interfaceis the critical lifeline used to synchronize state, heartbeats, and flow information between the Active and Standby ION devices.

The strict requirement for this connection is that it must beLayer 2 adjacent.

Best Practice:A direct physical cable connection between the designated HA ports of the two devices (e.g., Port 2 on Device A to Port 2 on Device B).

Alternative:Connectivity through a switch on a dedicated, isolated VLAN is supported, provided the devices are in the same broadcast domain and subnet.

Routing (Layer 3) isnot supportedfor the HA Control link because the keepalive mechanism relies on low-latency, multicast/broadcast-level adjacency to detect failures instantly (sub-second failover). If the HA link were routed (Option A), network latency or router convergence issues could cause "Split-Brain" scenarios where both devices assume the Active role, leading to IP conflicts and traffic loops. Option C is incorrect because the Controller is too slow to manage real-time failover; the decision must be local.