In ACI, by default, communication flows freely within EPGs, but not between EPGs. To enable inter-EPG communication, contracts are configured on the APIC. The configuration used in this guide is to allow unrestricted inter-EPG communication, as detailed in the Create Contract filter, Create Contract, and Apply Contract to VRF sections.
Connectivity is verified by pinging between the VMs as shown in the following figure. Since inter-EPG communication is allowed using configured contracts, all VMs can ping all other VMs in the topology.
The following figure shows the VM named app-01, in a rack server, successfully pinging the VMs named web-03 and db-04, which are on MX compute sleds.