In a Cisco ACI Multi-Pod deployment, the spine switches within a pod should not be directly connected to the spine switches in another pod. Instead, they should be connected to an IPN (Inter-Pod Network) device that provides Layer 3 IP connectivity between the pods. This setup allows for the extension of the ACI fabric across multiple locations while maintaining a single logical fabric. The IPN device can be a router or a switch with Layer 3 capabilities that can handle the necessary routing protocols and encapsulation methods required for Multi-Pod communication. References := Implementing Cisco Application Centric Infrastructure Official Cert Guide