What does the switchauto-networksetting control on FortiSwitch?

According to theFortiSwitchOS 7.6 Administration Guideand theFortiSwitch 7.6 Study Guide, the auto-network setting (configured via config switch auto-network) is a global feature introduced to simplify the initial deployment of switches. Starting inFortiSwitchOS 7.6.0and continuing through7.6, this feature isenabled by defaulton all new and factory-reset units.1

The primary function of theauto-networksetting is to facilitate theautomatic discovery of the FortiGate and the establishment of the FortiLink interface (Option B). When enabled, the switch automatically scans its physical ports to detect a management entity, such as a FortiGate controller. This " zero-touch " discovery mechanism allows the switch to identify the correct uplink ports and automatically configure them as members of theFortiLinkfabric without manual CLI or GUI intervention.

Furthermore, the documentation notes that auto-network also managesauto-topology, which allows two switches to automatically form anInter-Switch Link (ISL)trunk between them.2This includes setting the management VLAN (typically VLAN 4094) and ensuring that DHCP snooping is trusted on these discovered links.3If an administrator intends to use the switch in a strictly standalone mode without any auto-discovery or FortiLink features, the documentation specifies that they must manually disable the auto-network status and the auto-fortilink-discovery global settings to prevent the switch from attempting to join a managed fabric.4

Regarding other options:Option Arefers to Dynamic Port Policy or NAC features.Option Cis a standard STP configuration unrelated to the auto-network discovery suite.Option Dis a broader management capability that depends on successful network discovery but is not the specific control point for the auto-network setting.