RTP Control Protocol: Difference between revisions

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{{short description|Sister protocol of the Real-time Transport Protocol that provides control information}}

{{distinguish|Real Time Streaming Protocol}}

{{Infobox networking protocol

| title = RTP Control Protocol

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| osilayer =

| ports =

| rfcs = {{IETF RFC|3550|plainlink=yes}}

| hardware =

}}

{{distinguish|Real Time Streaming Protocol}}

{{short description|Sister protocol of the Real-time Transport Protocol that provides control information}}

The '''RTP Control Protocol''' ('''RTCP''') is a binary-encoded [[out-of-band signaling|out-of-band]] [[signaling protocol]] that functions alongside the [[Real-time Transport Protocol]] (RTP). Its basic functionality and packet structure is defined in RFC 3550. RTCP provides statistics and control information for an RTP session. It partners with RTP in the delivery and packaging of multimedia data but does not transport any media data itself.

The primary function of RTCP is to provide feedback on the [[quality of service]] (QoS) in media distribution by periodically sending statistics information such as transmitted [[Octet (computing)|octet]] and packet counts, [[packet loss]], [[packet delay variation]], and [[round-trip delay time]] to participants in a streaming multimedia session. An application may use this information to control quality of service parameters, perhaps by limiting flow, or using a different [[codec]].

{{Internet protocol suite|application=RTP Control Protocol}}

{{IPstack}}

== Protocol functions ==

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The Hierarchical Aggregation is used with [[Source-Specific Multicast]] where only a single source is allowed, i.e. [[IPTV]]. Another type of multicast could be [[Any-Source Multicast]] but it is not so suitable for large-scale applications with huge number of users.

{{asofas of|June 2007}}, only the most modern IPTV systems use Hierarchical aggregation.{{Citation needed|date=March 2009}}

=== Feedback Target ===

Feedback Target is a new type of member that has been firstly introduced by the Internet Draft draft-ietf-avt-rtcpssm-13.<ref{{Ref name=HA4/>RFC|5760}} The Hierarchical Aggregation method has extended its functionality. The function of this member is to receive Receiver Reports (RR) (see [[RTCP]]) and retransmit summarized RR packets, so-called Receiver Summary Information (RSI)<ref{{Ref name=HA4/>RFC|5760}} to a sender (in case of single-level hierarchy).

==Standards documents==

* {{Sum RFC|3550}}

* {{IETF RFC|3550}}, Standard 64, ''RTP: A Transport Protocol for Real-Time Applications''

==See also==

* [[Streaming media]]

* [[Voice over IP]]

==Notes==

{{reflist|group=lower-alpha}}

==References==

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<ref name=HA1>[https://web.archive.org/web/20070509035431/http://adela.utko.feec.vutbr.cz/projects/publications/#2 KOMOSNY D., NOVOTNY V. Tree Structure for Specific-Source Multicast with feedback Aggregation, in ICN07 - The Sixth International Conference on Networking . Martinique, 2007] {{ISBN|0-7695-2805-8}}</ref>

<ref name=HA2>[https://web.archive.org/web/20070509035431/http://adela.utko.feec.vutbr.cz/projects/publications/#2 NOVOTNY, V., KOMOSNY, D. Optimization of Large-Scale RTCP Feedback Reporting in ICWMC 2007. ICWMC 2007 - The Third International Conference on Wireless and Mobile Communications. Guadeloupe, 2007] {{ISBN|0-7695-2796-5}}</ref>

<ref name=HA4>{{cite IETF |RFC=5760 |author1=J. Ott |author2=J. Chesterfield |author3=E. Schooler |title=RTCP Extensions for Single-Source Multicast Sessions with Unicast Feedback}}</ref>

}}