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 explains how Real-time Transport
Protocol (RTP) streams can be duplicated without breaking RTP or RTP
Control Protocol (RTCP) rules.
Working Group Summary
The document went through a working group last call. There were
comments and the document was updated to resolve all comments.
The work was originally presented in the AVTCORE working group, but
following chair and AD discussion was adopted as a work item of the
AVTEXT group instead.
Document Quality
The document got good reviews from several AVText members, notably
Magnus Westerlund, who brought up several important topics about the
document's congestion control, and limitations of its source-association
mechanisms, which were resolved during working group last call.
Ali Begen says that Cisco uses duplicated streams "more or less"
according to the guidelines in this document, as do several other
implementations from the SMPTE community.
Personnel
The Document Shepherd is Jonathan Lennox. The Responsible Area Director
is Gonzalo Camarillo.