An Extension to the Session Description Protocol (SDP) and Real-time Transport Protocol (RTP) for Media Loopback
RFC 6849

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Internet Engineering Task Force (IETF)                    H. Kaplan, Ed.
Request for Comments: 6849                                   Acme Packet
Category: Standards Track                                     K. Hedayat
ISSN: 2070-1721                                                     EXFO
                                                                N. Venna
                                                                 Saperix
                                                                P. Jones
                                                     Cisco Systems, Inc.
                                                             N. Stratton
                                                         BlinkMind, Inc.
                                                           February 2013

         An Extension to the Session Description Protocol (SDP)
       and Real-time Transport Protocol (RTP) for Media Loopback

Abstract

   The wide deployment of Voice over IP (VoIP), real-time text, and
   Video over IP services has introduced new challenges in managing and
   maintaining real-time voice/text/video quality, reliability, and
   overall performance.  In particular, media delivery is an area that
   needs attention.  One method of meeting these challenges is
   monitoring the media delivery performance by looping media back to
   the transmitter.  This is typically referred to as "active
   monitoring" of services.  Media loopback is especially popular in
   ensuring the quality of transport to the edge of a given VoIP, real-
   time text, or Video over IP service.  Today, in networks that deliver
   real-time media, short of running 'ping' and 'traceroute' to the
   edge, administrators are left without the necessary tools to actively
   monitor, manage, and diagnose quality issues with their service.  The
   extension defined herein adds new Session Description Protocol (SDP)
   media types and attributes that enable establishment of media
   sessions where the media is looped back to the transmitter.  Such
   media sessions will serve as monitoring and troubleshooting tools by
   providing the means for measurement of more advanced VoIP, real-time
   text, and Video over IP performance metrics.

Kaplan, et al.               Standards Track                    [Page 1]
RFC 6849                   SDP Media Loopback              February 2013

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6849.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Kaplan, et al.               Standards Track                    [Page 2]
RFC 6849                   SDP Media Loopback              February 2013

Table of Contents

   1. Introduction ....................................................3
      1.1. Use Cases Supported ........................................4
   2. Terminology .....................................................6
   3. Overview of Operation ...........................................6
      3.1. SDP Offerer Behavior .......................................6
      3.2. SDP Answerer Behavior ......................................7