Since APIC Release 2.2(1n) Cisco enabled a feature called Preferred Groups. What does it and when do you need it? It allows defined EPGs in a VRF still to communicate with each other even when the Policy enforcement is enabled and there are no contract between those EPG’s. This can be, for example, really useful for migration scenarios. You can use them with all kind of EPG’s: EPG, uEPG or External EPG. But there are a few things you should be aware when you use it: You have to specify…