The initial APIC cluster discovery process involves each APIC using an  internal private IP address  from a pool to communicate with the nodes and other APICs in the cluster.  The APICs discover the IP addresses of other APIC controllers through an LLDP-based discovery process

To integrate the VMware vCenter cluster with Cisco ACI and ensure that the management traffic of the hypervisors and VM controllers uses the virtual switch associated with the Cisco Application Policy, the following steps must be taken:

Enable Infrastructure VLAN on AAEP used toward VMware hypervisors : This step involves enabling the infrastructure VLAN on the Attachable Access Entity Profile (AAEP) that is used for the VMware hypervisors. This VLAN is used for carrying infrastructure traffic such as management, vMotion, and fault tolerance.

Create a static binding in the target EPG toward VMware hypervisors with VLAN 300 : This step involves creating a static binding in the “Vmware-MGMT” EPG for the VMware hypervisors with VLAN 300, setting it as an untagged access VLAN, and using Untagged 802.1P mode. This ensures that the management traffic is correctly tagged and associated with the appropriate EPG.

References  :=

Cisco ACI Fabric Hardware Installation Guide

Cisco ACI Troubleshooting Guide

Cisco ACI Multi-Site Architecture White Paper

Cisco ACI Virtual Machine Manager (VMM) Integration White Paper

When traffic is received from a Layer 3 Out (L3Out) on the ingress leaf switch in a Cisco ACI fabric, the source IP address of the traffic is learned as a remote endpoint. This is because the traffic is entering the ACI fabric from an external network, and the source IP is considered remote to the fabric.