The IESG has approved the following document: - 'Duplication Grouping Semantics in the Session Description Protocol' (draft-ietf-mmusic-duplication-grouping-04.txt) as Proposed Standard This document is the product of the Multiparty Multimedia Session Control Working Group. The IESG contact persons are Gonzalo Camarillo and Richard Barnes. A URL of this Internet Draft is: http://datatracker.ietf.org/doc/draft-ietf-mmusic-duplication-grouping/ Technical Summary Packet loss is undesirable for real-time multimedia sessions, but can occur due to congestion, or other unplanned network outages. This is especially true for IP multicast networks, where packet loss patterns can vary greatly between receivers. One technique that can be used to recover from packet loss without incurring unbounded delay for all the receivers is to duplicate the packets and send them in separate redundant streams. This document defines the semantics for grouping redundant streams in the Session Description Protocol (SDP). The semantics defined in this document are to be used with the SDP Grouping Framework [RFC5888]. SSRC-level (Synchronization Source) grouping semantics are also defined in this document for RTP streams using SSRC multiplexing. Working Group Summary There is WG consensus behind this draft. All issues raised during and before WGLC have been addressed. Document Quality The document has received multiple reviews from working group participants and the document shepherd. There is currently at least one vendor implementing this mechanism and various other vendors have expressed interest for this technique. Personnel Who is the Document Shepherd? Who is the Responsible Area Director? Ari Keranen is the Document Shepherd, and the Responsible Area Director is Gonzalo Camarillo.