Neither Interest nor Data packets carry any host or interface addresses; routers forward Interest packets toward data producers based on the names carried in the packets, and forward Data packets to consumers based on the PIT state information set up by the Interests at each hop. This Interest/Data packet exchange symmetry induces a hop-by-hop control loop (not to be confused with symmetric routing, or with routing at all!), and eliminates the need for any notion of source or destination nodes in data delivery, unlike in IP's end-to-end packet delivery model.