To facilitate communication between the APIC controller and an OpenStack OpFlex agent, it's necessary to enable the Infra VLAN on the Attachable Access Entity Profile (AAEP). The AAEP is used in Cisco ACI to group interfaces that share common policies and extending the Infra VLAN to these interfaces allows the OpFlex agent, which is part of the Cisco Application Centric Infrastructure (ACI), to communicate with the APIC controller. This setup is crucial for the OpFlex agent to function correctly, as it relies on the Infra VLAN for communication with the APIC controller1. References: * Cisco ACI Installation Guide for Red Hat OpenStack Using the OpenStack Platform 13 Director1. * Cisco ACI Installation Guide for Red Hat OpenStack Using the OpenStack Platform 16.1 Director