Basic RTP Specs

Protocol specification:
RFC 3550.
Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth
RFC 3556
Proposal for additional RTP-SDES types
RTCP location reports
Jon Crowcroft
A RTCP-based Retransmission Protocol for Unicast RTP Streaming Multimedia
RTP Payload Type Format to Enable Selective Retransmissions
RTP extensions for reliable multicast
Alternatives for Enhancing RTP Scalability
Sampling of the Group Membership in RTP
Jonathan Rosenberg and Henning Schulzrinne
March 1999.
In large multicast groups, the size of the group membership table maintained by RTP (Real Time Transport Protocol) participants may become unwieldy, particularly for embedded devices with limited memory and processing power. This document discusses mechanisms for sampling of this group membership table in order to reduce the memory requirements. Several mechanisms are proposed, and the performance of each is considered.
Timer reconsideration for enhanced RTP scalability
Jonathan Rosenberg and Henning Schulzrinne
Internet Draft, Internet Engineering Task Force, July 1997
RTP, the Real Time Transport Protocol, has gained widespread acceptance as the transport protocol for voice and video on the Internet. It provides services such as timestamping, sequence numbering, and payload identification. It also contains a control component, the Real Time Control Protocol (RTCP), which is used for loose session control, QoS reporting, and media synchronization, among other functions. The RTP specification describes an algorithm for determining the RTCP packet transmission rate at a host participating in a multicast RTP session. This algorithm was designed to allow RTP to be used in sessions with anywhere from one to a million members. However, we have discovered several problems with this algorithm when used with very large groups with rapidly changing group membership. One problem is the flood of RTCP packets which occurs when many users join a multicast RTP session at nearly the same time. To solve this problem, we present a novel adaptive timer algorithm called reconsideration. We present a mathematical analysis of this algorithm, and demonstrate that it performs extremely well, reducing the congestion problem by several orders of magnitude. We also back up these results with simulation.
Issues in designing a transport protocol for audio and video conferences and other multiparticipant real-time applications
Henning Schulzrinne
expired Internet draft, Oct. 1993.
Elevating RTP to Protocol Status
Jonathan Rosenberg, Bernd Aboba, Henning Schulzrinne
March 1998.
This document discusses the issues involved in elevating RTP to the status of protocol, equivalent to TCP or UDP. This will result in all RTP packets being explicitly labeled as such in the packet header. This vastly simplifies the problem of classifying real time streams. Such classification operations are essential for successful deployment of RTP header compression, differentiated services, and traffic isolation. We define the format of the RTP protocol header, and discuss issues of backwards compatibility.
Discussion at 41st IETF, Los Angeles


Real-Time Transport Protocol Management Information Base

Last updated by Henning Schulzrinne