In ACI, by default, communication flows freely within EPGs but not between EPGs. To enable inter-EPG communication, contracts are configured on the APIC. This example is configured for unrestricted inter-EPG communication, as shown in steps 17 through 19 in the attachment: Dell PowerSwitch SmartFabric OS10 Deployment Guide with Cisco ACI.
Connectivity is verified by pinging between the VMs shown in Figure 6. Since inter-EPG communication is allowed using configured contracts, the VMs can ping all other VMs in the topology.
Figure 17 shows that the VM named app-01, located in a rack server, successfully pinged the VMs named web-03 and db-04, which are on the servers.