Pass the Fortinet Certified Solution Specialist FCSS_SDW_AR-7.4 Questions and answers with ValidTests

When the member priority of a port is increased (e.g., port2 to 20), FortiGate evaluates existing sessions and applies “dirty” flags where applicable. The SD-WAN session management mechanism is described in detail: “Upon a change in SD-WAN member priority, all existing sessions using that member are marked as dirty. For SNAT sessions, the gateway information is updated to ensure future packets are routed through the newly preferred member, in this case, port1. This automatic re-evaluation allows SD-WAN to dynamically respond to topology or priority changes, maintaining optimal routing.” This is fundamental to seamless failover and session persistence in Fortinet SD-WAN, ensuring active flows are redirected based on updated priorities or health status.

The diagnose output shows multiple ADVPN tunnels (HUB1-VPN1, HUB1-VPN2, HUB1-VPN3) with detailed latency, jitter, and packet loss values being reported for each. In ADVPN, the spoke performs embedded health checks and provides the hub with the performance metrics for each tunnel. Therefore, the device in the exhibit is a spoke, and it is sending health-check measurements for each tunnel to the hub.

The use of SLA targets is specific to certain SD-WAN strategies. The "Lowest Cost (SLA)" and "Maximize Bandwidth (SLA)" strategies are explicitly designed to use the configured SLA targets to make routing decisions. The "Best Quality" strategy uses performance metrics but does not necessarily require or reference SLA targets in the same way, while "Manual" does not use metrics at all for path selection.

This is a core function of SD-WAN rules with SLA targets. The purpose of configuring an SLA target with specific thresholds for latency, jitter, and packet loss is to define what is considered "acceptable" performance for an application. SD-WAN rules then use these targets to check if the members (interfaces) meet these requirements before a flow is steered over them, ensuring that a preferred path still offers a good user experience.

FortiGate allows for a single SD-WAN rule to reference multiple, different performance SLAs. This is crucial for complex deployments where a single SD-WAN rule needs to handle traffic for multiple applications that have distinct performance requirements. For example, a single rule might direct VoIP traffic based on one performance SLA with strict latency/jitter targets, while simultaneously handling general web traffic using another performance SLA with more lenient requirements.

Specify the gateway of the SD-WAN member port1 with an IP address or use the default value → The error log shows invalid ip – prop[gateway]: ip4class(${sdwan_port1_gw}) invalid ip addr, meaning the variable ${sdwan_port1_gw} does not have a valid mapping. Assigning a valid IP address or default value for the gateway resolves this error.

Review the per-device mapping configuration for metadata variables → The issue is tied to how the metadata variable ${sdwan_port1_gw} is mapped for branch1_fgt. If this device does not have the variable properly defined in per-device mapping, the configuration will fail. Correcting the mapping ensures that the install works.

Event logs (from the exhibit) show how traffic is matched to SD-WAN rules and routed. The log output indicates that voice traffic is being routed through the HUB1-VPN3 tunnel. This matches SD-WAN's application-aware steering, which uses dynamic performance metrics to select the optimal path.

Rules template → Defines the SD-WAN rules for traffic steering.

BGP template → Configures dynamic routing for overlay tunnels.

IPsec tunnel template → Builds the IPsec VPN tunnels from the spoke to the hubs.

FortiGate passively monitors the member if TCP traffic is passing through the member → With Prefer Passive mode, FortiGate inspects existing traffic (like TCP flows) to measure performance metrics without generating its own probes.

FortiGate passively monitors the member if ICMP traffic is passing through the member → Similarly, when ICMP flows exist, FortiGate uses them for SLA checks.