A Network Address Translator (NAT) Traversal Mechanism for Media Controlled by the Real-Time Streaming Protocol (RTSP)
RFC 7825

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Internet Engineering Task Force (IETF)                       J. Goldberg
Request for Comments: 7825                                         Cisco
Category: Standards Track                                  M. Westerlund
ISSN: 2070-1721                                                 Ericsson
                                                                 T. Zeng
                                                 Nextwave Wireless, Inc.
                                                           December 2016

    A Network Address Translator (NAT) Traversal Mechanism for Media
         Controlled by the Real-Time Streaming Protocol (RTSP)

Abstract

   This document defines a solution for Network Address Translation
   (NAT) traversal for datagram-based media streams set up and
   controlled with the Real-Time Streaming Protocol version 2 (RTSP
   2.0).  It uses Interactive Connectivity Establishment (ICE) adapted
   to use RTSP as a signaling channel, defining the necessary RTSP
   extensions and procedures.

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 7841.

   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/rfc7825.

Goldberg, et al.             Standards Track                    [Page 1]
RFC 7825        A Media NAT Traversal Mechanism for RTSP   December 2016

Copyright Notice

   Copyright (c) 2016 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Key Words .......................................................4
   3. Solution Overview ...............................................4
   4. RTSP Extensions .................................................6
      4.1. ICE Transport Lower Layer ..................................6
      4.2. ICE Candidate Transport Header Parameter ...................8
      4.3. ICE Password and Username Transport Header Parameters .....11
      4.4. ICE Feature Tag ...........................................11
      4.5. Status Codes ..............................................12
           4.5.1. 150 Server still working on ICE
                  connectivity checks ................................12
           4.5.2. 480 ICE Connectivity check failure .................12
      4.6. New Reason for PLAY_NOTIFY ................................12
      4.7. Server-Side SDP Attribute for ICE Support .................13
   5. ICE-RTSP .......................................................13
      5.1. ICE Features Not Required .................................13
           5.1.1. ICE-Lite ...........................................13
           5.1.2. ICE-Mismatch .......................................13
           5.1.3. ICE Remote Candidate Transport Header Parameter ....14
      5.2. High-Reachability Configuration ...........................14
   6. Detailed Solution ..............................................14
      6.1. Session Description and RTSP DESCRIBE (Optional) ..........14
      6.2. Setting Up the Media Streams ..............................15
      6.3. RTSP SETUP Request ........................................16
      6.4. Gathering Candidates ......................................16
      6.5. RTSP Server Response ......................................17
      6.6. Server-to-Client ICE Connectivity Checks ..................18
      6.7. Client-to-Server ICE Connectivity Check ...................19
      6.8. Client Connectivity Checks Complete .......................20
      6.9. Server Connectivity Checks Complete .......................20
      6.10. Freeing Candidates .......................................20

Goldberg, et al.             Standards Track                    [Page 2]
RFC 7825        A Media NAT Traversal Mechanism for RTSP   December 2016

      6.11. Steady State .............................................21
      6.12. Re-SETUP .................................................21