IETF RFC 6332 PDF

In most RTP-based multicast applications, the RTP source sends interrelated data. Due to this interdependency, randomly joining RTP receivers usually cannot start consuming the multicast data right after they join the session. Thus, they often experience a random acquisition delay. An RTP receiver can use one or more different approaches to achieve rapid acquisition. Yet, due to various factors, performance of the rapid acquisition methods usually varies. Furthermore, in some cases, the RTP receiver can do a simple multicast join (in other cases, it is compelled to do so). For quality reporting, monitoring, and diagnostic purposes, it is important to collect detailed information from the RTP receivers about their acquisition and presentation experiences. This document addresses this issue by defining a new report block type, called the Multicast Acquisition (MA) report block, within the framework of RTP Control Protocol (RTCP) Extended Reports (XRs) (RFC 3611). This document also defines the necessary signaling of the new MA report block type in the Session Description Protocol (SDP).