What Is RTP?

Date First Published: 5th June 2022

Topic: Computer Networking

Subtopic: Internet Protocols

Article Type: Computer Terms & Definitions

Difficulty Level: 7/10

Learn more about what RTP is in this article.

Not to be confused with RTSP (Real-Time Streaming Protocol)

Real-time transport protocol (RTP) is a protocol used for delivering live media over the internet, such as audio, video playing, VoIP, gaming, live broadcasts, and internet telephony. RTP communicates over UDP, since that transport protocol transmits data before an agreement is provided by the receiving party, allowing data to be transmitted more quickly. It prioritises the quick delivery of data over ensuring that all data is received, reducing latency. Even though it is possible for RTP to use TCP as the transport protocol, it is not recommended due to its time-sensitive transmissions.

RTP was developed by the Audio-Video Transport Working Group of the IETF and defined in RFC 1889. Later on, it was superseded by RFC 3550 in 2003.

Any port number can be used with RTP. It will be in the port range of 1024 to 65535, which are common ports that anyone can use for their servers. IANA has registered port 5004 for RTP and port 5005 for RCTP. RTP will be an even-numbered port and RCTP will be the next odd-numbered port.

Uses Of RTP

RTP would be used when a user wanted to watch a video on the internet without downloading it to their device. RTP would be used by the video streaming service to send the video data to their computer.

Most online audio and video services, such as FaceTime, Google Meet, and Microsoft Teams use RTP. The real-time streaming protocol (RTSP) is an extension to RTP and it allows users to control the delivery of real-time streaming content over the internet. An example of the use of RTSP is when a user pauses the video that they are streaming. RTSP will transfer the user’s request to pause the video to the server. Even though RTSP and RTP look very similar, these two protocols perform different functions. RTP is the transport protocol used for delivering live media over the internet and RTSP allows users to control the streaming of media over RTP.

Note:

RTP itself does not provide any encryption or authentication methods. Secure real-time transport protocol (SRTP) can be used to encrypt RTP communications so that the sent data cannot be read by anyone if intercepted.

Other Protocols

RTP is often used in combination with other protocols, such as:

• Real-Time Transport Control Protocol (RTCP). This allows monitoring of data delivery on large multicast networks and sends quality of service information, such as packet loss, packet delay variation, jitter, round-trip delay time, and transmitted octet and packet counts to participants in a streaming multimedia session.
• Session Initiation Protocol (SIP). A signalling protocol that is used to initiate, maintain, and terminate communication sessions with network devices.