RTCP Hierarchical Aggregation
The Hierarchical Aggregation (or also known as RTCP feedback hierarchy) is an optimization of the RTCP feedback model and its aim is to shift the maximum number of users limit further together with Quality of Service (QoS) measurement, . The RTCP bandwidth is constant and takes just 5% of session bandwidth. Therefore the reporting interval about QoS depends, among others, on a number of session members and for very large sessions it can become very high (minutes or even hours). However the acceptable interval is about 10 seconds of reporting. Bigger values would cause time-shifted and very inaccurate reported status about the current session status and any optimization made by sender could even have a negative effect to network or QoS conditions.
The Hierarchical Aggregation is used with Source-Specific Multicast where only a single source is allowed, i.e. IPTV. The another type of multicast could be Any-Source Multicast but it is not so suitable for large-scale applications with huge number of users.
Only the most modern IPTV systems use Hierarchical aggregation (June 2007).
Read more about RTCP Hierarchical Aggregation: Feedback Target, Schema
Famous quotes containing the word hierarchical:
“Authority is the spiritual dimension of power because it depends upon faith in a system of meaning that decrees the necessity of the hierarchical order and so provides for the unity of imperative control.”
—Shoshana Zuboff (b. 1951)