In the TCP/IP protocol suite, a mechanism for providing endto-end network transport functions suitable for applications transmitting real-time data, such as audio, video, or simulation data, over multicast or unicast network services. Defined in IETF RFC 1889 (1996), RTP provides end-to-end delivery services including payload type identification, sequence numbering, and timestamping. In combination, the sequence numbering and timestamping provide the receiving node with sufficient information to resequence them as necessary. RTP does not address resource reservation and does not guarantee quality of service (QoS) for real-time services. RTP does not either guarantee delivery through the network or prevent out-of-order delivery, and it does not assume that the underlying network is reliable and delivers datagrams in sequence to the receiving machine. RTP does, however, prevent out-of-order delivery to the application. Applications such as voice over Internet Protocol (VoIP) generally run RTP on top of the User Datagram Protocol (UDP), which provides multiplexing and checksum services. In the context of the OSI Reference Model, RTP falls into both the Session Layer (Layer 5) and the Presentation Layer (Layer 6). RTP Control Protocol (RTCP) is an upper-layer companion protocol that allows monitoring of the data delivery. See also application, checksum, datagram, IETF, multicast, multiplex, payload, Presentation Layer, protocol, protocol suite, QoS, real-time, RTCP, Session Layer, TCP/IP, transport, UDP, unicast, and VoIP.
(1) (Rapid Transport Protocol) The protocol used in IBM's High Performance Routing (HPR) system.
(2) (Realtime Transport Protocol) An IP protocol that supports real-time transmission of voice and video. It is widely used for IP telephony and audio and video streaming. An RTP packet rides on top of UDP, the non-reliable counterpart of TCP, and includes timestamping and synchronization information in its header for proper reassembly at the receiving end. Secure RTP (SRTP) is a version of RTP that provides confidentiality and message authentication. RTCP (Real Time Control Protocol) RTCP is a companion protocol to RTP that is used to maintain QoS. RTP nodes analyze network conditions and periodically send each other RTCP packets that report on network congestion. RTSP (Real Time Streaming Protocol) RTSP is used to control an RTP session at the application layer. It enables functions such as pause, rewind and fast forward to be provided in the user's client software. See IP telephony, RSVP and UDP.