How does a Cisco APIC discover a new switch in the fabric?

APIC policies are used for configuring the fabric after discovery, but the initial physical switch discovery relies on low-level protocols like LLDP.

While APIC cluster nodes are central to the fabric, the discovery is not a simple query but an active process initiated by the switches themselves using LLDP and then coordinated by the APIC.

When a new Cisco ACI switch is connected and powered on, it uses LLDP to discover its neighbors, including the APIC or other ACI switches. The APIC then initiates a cascading discovery process, using the directly connected switches to find and learn about other switches in the fabric, thereby building the complete network topology.

SNMP is used for monitoring and management of network devices once they are discovered and operational, not for the initial fabric discovery process in Cisco ACI.