NSE6_SDW_AD-7.6 Questions and Answers

FortiManager enforces a strict distinction:

"Firewall policies must reference SD-WAN zones, not individual SD-WAN members, when used in conjunction with SD-WAN templates. Attempting to install a policy that references a specific member (interface) will result in a deployment error, as member-level targeting is not supported in SD-WAN policy abstraction. This enforces centralized policy consistency and proper SD-WAN operation."

Ensuring policies target zones allows FortiGate to dynamically select the optimal member.

Policy 3 points traffic To = HUB1-VPN1, which is an SD-WAN member interface. In SD-WAN you must reference the SD-WAN zone (the logical interface) in policies, not its member tunnels. Change the policy’s To interface to the zone HUB1, and the install will succeed.

For FortiGate to steer traffic using SD-WAN rules, two foundational elements must be in place: available WAN paths (underlay links) and firewall policies that allow traffic to reach the SD-WAN interface.

Underlay links (Option B) are mandatory because SD-WAN operates by selecting among multiple WAN transports (for example, broadband, MPLS, LTE, or IPsec tunnels). These links are configured as SD-WAN members and form the physical or logical paths over which traffic can be steered. Without underlay links, SD-WAN has no paths to evaluate or select.

Firewall policies (Option E) are also mandatory because FortiGate only processes and forwards traffic that is explicitly permitted by a firewall policy. When SD-WAN is enabled, firewall policies must reference the SD-WAN interface or SD-WAN zone as the outgoing interface. If no such policy exists, traffic will not be forwarded and SD-WAN rules will never be evaluated.

Why the other options are incorrect:

Security profiles (Option A) are optional and relate to inspection, not SD-WAN steering.

Overlay links (Option C) are used in specific designs such as ADVPN or hub-and-spoke overlays, but SD-WAN can steer traffic without overlays (for example, DIA-only designs).

Traffic shaping (Option D) is not required for SD-WAN decision-making; it is an optional optimization feature.

Therefore, the two required features that must be configured before FortiGate can steer traffic according to SD-WAN rules are underlay links and firewall policies, which correspond to B and E.

For SD-WAN deployments that span multiple regions—where most traffic is intra-region and there is no requirement for inter-region ADVPN—the best practice is to use IBGP with BGP on loopback interfaces for routing within each region and EBGP between the regions. This approach ensures robust and scalable routing, isolates regional routing domains, and enables policy control at region boundaries. BGP on loopback is preferred for its reliability and flexibility, as it enables peering that is not tied to specific physical interfaces. EBGP between regions allows each region to maintain independent routing policies and summarization, optimizing performance and manageability. By separating IBGP (intra-region) and EBGP (inter-region), you create a modular architecture that scales easily and simplifies fault isolation and troubleshooting.

In the exhibit, the IPsec tunnel statistics event log entries include the field advpnsc.

Fortinet documents that advpnsc identifies whether the VPN event is based on an ADVPN shortcut:

advpnsc=1 → the tunnel is an ADVPN shortcut

advpnsc=0 → not an ADVPN shortcut (Fortinet Documentation Library)

In the shown logs, the tunnel vpntunnel="HUB1-VPN1_0" has advpnsc=1, which means HUB1-VPN1_0 is an ADVPN shortcut tunnel. (Fortinet Documentation Library)

The other tunnels shown (for example VPN4_0 and HUB2-VPN3) have advpnsc=0, which only indicates no shortcut is identified for those log entries—it does not prove they “cannot accept” shortcuts, only that the specific event is not a shortcut. (Fortinet Documentation Library)

From the exhibit, both branches have an SD-WAN zone named overlay with set advpn-select enable, and each SD-WAN member in that zone is assigned a transport-group value.

Branch-A members:

T1 → transport-group 1

T2 → transport-group 1

T3 → transport-group 2

Branch-B members:

TA → transport-group 1

TB → transport-group 2

TC → transport-group 3

In FCSS SD-WAN 7.6 ADVPN design, transport-group is used to constrain which underlays are allowed to form ADVPN shortcuts with each other. A spoke can establish an ADVPN shortcut only between interfaces that belong to the same transport-group on both sides. This prevents building shortcuts across dissimilar transports.

Evaluating the options:

Option D (T2 on Branch-A with transport-group 1 and TA on Branch-B with transport-group 1) is a valid shortcut pairing.

Option C is not valid because T3 is transport-group 2 while TC is transport-group 3, so they are not permitted to form a shortcut.

Option A is incorrect because not all overlay-zone interfaces are eligible; eligibility is restricted by transport-group matching.

Option B is incorrect because ADVPN shortcuts are spoke-to-spoke tunnels (facilitated by the hub), not limited to “interfaces connected to hub only.”

Therefore, the valid shortcut pairing listed is between T2 on Branch-A and TA on Branch-B, which corresponds to Option D.

Your requirements map to two key MSSP goals described in the FCSS SD-WAN 7.6 blueprint patterns:

Delegate as much administration and management as possible to the MSSPThis is best achieved when the hub security and SD-WAN control point is located on the MSSP premises, because the MSSP can centrally operate the core enforcement and overlay control. Both option B (dedicated hub at MSSP) and option D (shared hub at MSSP with customer isolation) meet this requirement.

Each site must maintain direct internet access (DIA) and be secure, with significant site-to-site trafficIn Fortinet SD-WAN MSSP designs, spokes can still use local breakout for DIA while also building secure overlays for inter-site traffic. Placing the hub at the MSSP enables centralized security services and scalable inter-site connectivity management while preserving DIA where required. Options B and D support this operating model.

Why the other options do not best match:

A includes a dedicated hub on the customer premises, which reduces how much the MSSP can centralize and operate from its own environment, so it does not maximize delegation.

C places both hub and spokes on the customer premises. While the MSSP can manage using a dedicated ADOM, this blueprint does not align as strongly with “delegate installation and management” to the MSSP as the designs where the hub is hosted and operated from the MSSP premises.

Therefore, the two MSSP deployment blueprints that address your requirements are B and D.

The SD-WAN rule (config service edit 1) is configured with set mode priority. This means the rule selects the best interface based on a defined performance metric, as opposed to a simple static priority or SLA. The event log (image_41cfb5.png) shows Metric latency and Message Service prioritized by performance metric will be redirected in sequence order. This indicates that the rule is using latency to determine the preferred member. Given that the log message is about a change, and the most logical reason for a change in a priority mode is that a different member is now the best performer, it implies that the latency on port2 has become lower than that on port1.

The log message Service prioritized by performance metric will be redirected in sequence order confirms that FortiGate is changing the member being used for this service. Because the mode is priority, FortiGate dynamically selects the member that currently meets the best performance criteria, which in this case is latency. The log implies a new member has been selected as the most optimal, and with the default configuration, the members are sorted based on their performance, so the outgoing interface list is effectively updated to prefer the new best-performing member (port2).

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.

Fortinet outlines key SD-WAN routing principles:

"Policy routes are always evaluated before SD-WAN rules, meaning if a policy route matches, SD-WAN steering is bypassed. If the best route for a destination is not via an SD-WAN member, SD-WAN rules do not apply, and members are ignored if they lack a valid route. This hierarchy ensures traffic always follows the most deterministic and valid path according to configuration."

Understanding these principles is critical for correct SD-WAN and routing integration.

With the Best Quality strategy, FortiGate first checks which links meet the SLA targets defined in the selected performance SLA (in this case, Custom-profile-1). Among those qualified links, FortiGate then uses the member configuration order to decide preference. If multiple links still qualify, it finally considers the member local cost to select the best path.

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.

In the SD-WAN GUI, the absence of members in a zone is visually represented, and the Fortinet guide confirms:

"If a zone such as overlay-factories contains no members, it will be displayed as empty in the SD-WAN GUI. This may occur when the zone is reserved for future expansion, or if members have been temporarily removed for maintenance or reconfiguration. Traffic cannot be steered via an empty zone until at least one SD-WAN member is added."

Such visual cues help operators quickly assess configuration status and readiness.

The FortiManager SD-WAN overlay system allows only one IPsec template to be assigned to each device per overlay operation. The guide clarifies:

"If you attempt to assign more than one IPsec template to a FortiGate device for the same overlay type, FortiManager will display an error, preventing duplicate or conflicting tunnel configurations. This limitation ensures a one-to-one mapping between device and overlay template per operation, maintaining configuration integrity and preventing routing issues."

This prevents complex troubleshooting scenarios and enforces best practices for overlay design.

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.

When referencing a zone in a static route, FortiGate’s behavior is described as:

"Referencing a zone in a static route causes FortiGate to install a static route for each member interface of the zone. This enables ECMP (Equal-Cost Multi-Path) and load balancing where supported and ensures that traffic can be steered over any valid zone member according to SD-WAN rules or standard routing."

This mechanism is fundamental to Fortinet’s implementation of SD-WAN and simplifies large, multi-interface deployments.

To allow spokes in different hub-and-spoke groups to establish ADVPN shortcuts, the hubs must be configured to forward and send ADVPN shortcut offers. The key required settings on the hub are auto-discovery-forwarder (for VPNs to hubs) and auto-discovery-sender (for VPNs to spokes). This ensures the hub can facilitate and advertise ADVPN shortcut offers between spokes.

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.

In FortiOS 7.6, static routes can reference either:

an SD-WAN zone (for example, virtual-wan-link or a user-defined SD-WAN zone), or

a specific SD-WAN member interface that belongs to that zone.

However, FortiOS enforces a routing constraint to avoid ambiguity during route resolution. Two static routes cannot have the same destination prefix if one points to an SD-WAN zone and the other points to an SD-WAN member within that zone. This would create an overlapping and conflicting forwarding decision.

Therefore, if you configure:

one static route that references an SD-WAN zone, and

another static route that references an SD-WAN member belonging to that same zone,

the destination subnets of the two static routes must be different.

Why the other options are incorrect:

Option A is incorrect because FortiOS does allow static routes that reference individual SD-WAN members.

Option B is incorrect because static routes can reference SD-WAN zones.

Option D is incorrect because static routing decisions in FortiOS are based on destination prefixes, not source prefixes.

Thus, the correct answer is C.