Cisco ACI Fabric discovery prerequisites include:

• Initial cabling of the Cisco ACI fabric.

• Initial setup of the Cisco APIC cluster over the out-of-band network.

• To run the same version of firmware on Cisco APIC nodes and switches

It is important to follow the mandatory prerequisitesfor the cabling of the Cisco ACI:

• Spines can only be connected to leaves. Spines cannot be interconnected.

• Leaves can only be connected to spines. There should be no cabling between the leaves.

• All endpoints, Layer 2, Layer 3, Layer 4-Layer 7 devices must connect to leaves.

• A Cisco APIC must be attached to a leaf and dual-homed, which means that it must be connected to two different leaves.

The Cisco ACI Fabric discovery is an automated process which uses Link Layer Discovery Protocol (LLDP) and DHCP-based approach to discover the switch nodes, assign infrastructure VTEP addresses and install the needed firmware.Before the start of the discovery process is needed to perform a minimal bootsrap configuration in the Cisco APIC console.

When the Cisco APIC is launched for the first time, in the console are presented a series of initial setup options. For many options, you can press Enter to choose the default setting that is displayed in brackets. At any point in the setup dialog, you can restart the dialog from the beginning by pressing Ctrl+C.

The following parameters will be configured during the initial setup:

• Fabric name, number of controllers, controller ID, and controller name: First, you have to enter the fabric name, number of controllers (default is 3), and controller ID. The controller ID is a unique ID number for the Cisco APIC instance: 1, 2, or 3, and the controller name.

• Address pool for TEP addresses: Enter the address pool for tunnel endpoint (TEP) addresses. The default IP address pool for TEP tunnel endpoint addresses is 10.0.0.0/16. This value is for the infrastructure virtual routing and forwarding (VRF) only. This subnet should not overlap with any other routed subnets in your network. If this subnet does overlap with another subnet, change this subnet to a different /16 subnet. The minimum supported subnet for a 3-APIC cluster is a /23.

• VLAN ID for infra network: Enter the VLAN ID for infrastructure network. This infrastructure VLAN serves for APIC-to-switch communication including virtual switches. Reserve this VLAN for APIC use only. This VLAN ID must not be used elsewhere in your environment and must not overlap with any other reserved VLANs on other platforms. Cisco recommends VLAN 3967.

• Out-of-band management IP address: Enter the IP address for the out-of-band management, which is the IP address that you use to access the Cisco APIC through the GUI, CLI, or API.

• Default gateway IP address: Enter the IP address of the default gateway for communication to external networks using out-of-band management.

• Admin password: Set the password. The password of the system administrator must be at least 8 characters long with one special character.