Peer-to-peer (P2P) communication is the real-time transfer of data and media between clients.
Real Time Media Flow Protocol (RTMFP) is an Adobe proprietary protocol. It enables peer-to-peer communication between applications running in Flash Player or the AIR runtime. It is meant to provide a low-latency, secure, peering network experience.
Real Time Messaging Protocol (RTMP) uses Transmission Control Protocol (TCP). RTMFP uses User Datagram Protocol (UDP), which provides better latency, higher security (128-bit AES encryption), and scalability. RTMP is faster than RTMFP, but does not guarantee perfect message ordering and delivery.
RTMP was designed to connect via an RTMFP-capable server, such as the Cirrus service (RTMP uses the Flash Media Server), but it can also be used over a local network using WiFi without the need for a server. Note that Flash Media Server 4.0 speaks RTMFP as well.