You are deploying a small office network with a single FortiGate and a single FortiSwitch.

According to theFortiGate Switch Best Practicesand theFortiSwitch 7.6 FortiLink Guide, the recommended best practice for a scalable and high-performance FortiLink deployment is to use alink aggregation group (LAG)interface, also known as an802.3ad aggregate.3

While ahardware-based switch interface (Option A)offers low latency by switching traffic directly in the ASIC, it has significant limitations regardingscalability and redundancy. Hardware switches are restricted by the number of physical ports on the Integrated Switch Fabric (ISF) and cannot be easily expanded to include additional redundant links as the network grows. Conversely,software-based switch interfaces (Option B)are processed by the system CPU, leading to higher utilization and a lack ofNPU hardware acceleration, which makes them unsuitable for high-performance or growing environments.4

By configuring FortiLink as aLAG (Option C), the administrator ensures that the network can support future growth seamlessly. A LAG interface allows for the addition of multiple physical ports to increase bandwidth between the FortiGate and the switch fabric while providing link-level redundancy.5This configuration is the default for modern FortiOS versions because it supports NPU offloading and serves as the technical prerequisite for more advanced topologies, such asMCLAG (Option D). While MCLAG is an excellent solution for high availability in multi-switch environments, it is a topology feature rather than the primary interface type used to define the FortiLink connection on the FortiGate unit itself. Therefore, starting with an aggregate (LAG) interface provides the most flexible foundation for migrating to more complex infrastructures as additional switches are added.