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Internet Engineering Task Force (IETF)                     S. NandakumarRequest for Comments: 7850                             Cisco Systems IncCategory: Standards Track                                     April 2016ISSN: 2070-1721Registering Values of the SDP 'proto' Fieldfor Transporting RTP Media over TCP under Various RTP ProfilesAbstract   The Real-time Transport Protocol (RTP) specification establishes a   registry of profile names for use by higher-level control protocols,   such as the Session Description Protocol (SDP), to refer to the   transport methods.  This specification describes the following new   SDP transport protocol identifiers for transporting RTP Media over   TCP: 'TCP/RTP/AVPF', 'TCP/RTP/SAVP', 'TCP/RTP/SAVPF',   'TCP/DTLS/RTP/SAVP', 'TCP/DTLS/RTP/SAVPF', 'TCP/TLS/RTP/AVP', and   'TCP/TLS/RTP/AVPF'.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 inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7850.Copyright Notice   Copyright (c) 2016 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.Nandakumar                   Standards Track                    [Page 1]

RFC 7850                SDP 'proto' Registrations             April 2016Table of Contents1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .22.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .33.  Protocol Identifiers  . . . . . . . . . . . . . . . . . . . .33.1.  TCP/RTP/AVPF Transport Realization  . . . . . . . . . . .33.2.  TCP/RTP/SAVP Transport Realization  . . . . . . . . . . .33.3.  TCP/RTP/SAVPF Transport Realization . . . . . . . . . . .33.4.  TCP/DTLS/RTP/SAVP Transport Realization . . . . . . . . .33.5.  TCP/DTLS/RTP/SAVPF Transport Realization  . . . . . . . .43.6.  TCP/TLS/RTP/AVP Transport Realization . . . . . . . . . .43.7.  TCP/TLS/RTP/AVPF Transport Realization  . . . . . . . . .44.  ICE Considerations  . . . . . . . . . . . . . . . . . . . . .45.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .46.  Security Considerations . . . . . . . . . . . . . . . . . . .57.  References  . . . . . . . . . . . . . . . . . . . . . . . . .57.1.  Normative References  . . . . . . . . . . . . . . . . . .57.2.  Informative References  . . . . . . . . . . . . . . . . .6   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .7   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .71.  Overview   The Real-time Transport Protocol (RTP) provides end-to-end network   transport functions suitable for applications transmitting real-time   data such as audio or video over multicast or unicast network   services.  The data transport is augmented by the RTP Control   Protocol (RTCP) to allow monitoring of the data delivery in a manner   scalable to large multicast networks and to provide minimal control   and identification functionality.   "SDP: Session Description Protocol" [RFC4566] provides a general-   purpose format for describing multimedia sessions in announcements or   invitations.  "TCP-Based Media Transport in the Session Description   Protocol (SDP)" [RFC4145] specifies a general mechanism for   describing media transport over TCP using SDP with [RFC4571] defining   a method for framing RTP and RTCP packets [RFC3550] onto a   connection-oriented transport (such as TCP).  "Connection-Oriented   Media Transport over the Transport Layer Security (TLS) Protocol in   the Session Description Protocol (SDP)" [RFC4572] extends [RFC4145]   for describing TCP-based media streams that are protected using TLS   [RFC5246].   This specification describes additional SDP transport protocol   identifiers for transporting RTP media over TCP as defined inSection 3.Nandakumar                   Standards Track                    [Page 2]

RFC 7850                SDP 'proto' Registrations             April 20162.  Terminology   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described inRFC 2119 [RFC2119].3.  Protocol Identifiers   The "m=" line in SDP specifies, among other items, the transport   protocol (identified via the "proto" field) to be used for the media   in the session.  SeeSection 5.14 (Media Descriptions) of SDP   [RFC4566] for a discussion on transport protocol identifiers.   The following is the format for an "m=" line, as specified in   [RFC4566]:             m=<media> <port> <proto> <fmt> ...3.1.  TCP/RTP/AVPF Transport Realization   The TCP/RTP/AVPF transport describes RTP media with RTCP-based   feedback [RFC4585] over TCP.   The RTP/AVPF stream over TCP is realized using the framing method   defined in [RFC4571].3.2.  TCP/RTP/SAVP Transport Realization   The TCP/RTP/SAVP transport describes Secure RTP (SRTP) media   [RFC3711] over TCP.   The RTP/SAVP stream over TCP is realized using the framing method   defined in [RFC4571].3.3.  TCP/RTP/SAVPF Transport Realization   The TCP/RTP/SAVPF transport describes Secure RTP media with RTCP-   based feedback [RFC5124] over TCP.   The RTP/SAVPF stream over TCP is realized using the framing method   defined in [RFC4571].3.4.  TCP/DTLS/RTP/SAVP Transport Realization   The TCP/DTLS/RTP/SAVP transport describes Secure RTP media [RFC3711]   using Datagram Transport Layer Security SRTP (DTLS-SRTP) [RFC5764]   over TCP.Nandakumar                   Standards Track                    [Page 3]

RFC 7850                SDP 'proto' Registrations             April 2016   RTP/SAVP using DTLS-based key establishment is realized according to   the procedures defined in [RFC5764].  Also, the framing specified in   [RFC4571] is used to transport DTLS-SRTP packets over TCP.3.5.  TCP/DTLS/RTP/SAVPF Transport Realization   The TCP/DTLS/RTP/SAVPF transport describes Secure RTP media with   RTCP-based feedback [RFC5124] using DTLS-SRTP over TCP.   RTP/SAVPF using DTLS-based key establishment is realized according to   the procedures defined in [RFC5764].  Also, the framing specified in   [RFC4571] is used to transport DTLS-SRTP packets over TCP.3.6.  TCP/TLS/RTP/AVP Transport Realization   The TCP/TLS/RTP/AVP transport describes RTP Media on top of TLS over   TCP.   RTP/AVP packets are framed using the procedures from [RFC4571] and   are transported as application data messages over the TLS association   setup using the procedures from [RFC4572].3.7.  TCP/TLS/RTP/AVPF Transport Realization   The TCP/TLS/RTP/AVPF transport describes RTP media with RTCP-based   feedback [RFC5124] on top of TLS over TCP.   RTP/AVPF packets are framed using the procedures from [RFC4571] and   are transported as application data messages over the TLS association   setup using the procedures from [RFC4572].4.  ICE Considerations   When procedures from [RFC6544] are used to set up Interactive   Connectivity Establishment (ICE) [RFC5245] candidates for a TCP   transport, the framing mechanism from [RFC4571] MUST be used for   framing Session Traversal Utilities for NAT (STUN) packets (for   keepalives and consent checks), as defined inSection 3 of [RFC6544].5.  IANA Considerations   This specification describes the following new SDP transport protocol   identifiers: 'TCP/RTP/AVPF', 'TCP/RTP/SAVP', 'TCP/RTP/SAVPF',   'TCP/DTLS/RTP/SAVP', 'TCP/DTLS/RTP/SAVPF', 'TCP/TLS/RTP/AVP', and   'TCP/TLS/RTP/AVPF', as defined inSection 3.  These values have been   registered by the IANA under the "proto" subregistry in the "Session   Description Protocol (SDP) Parameters" registry.Nandakumar                   Standards Track                    [Page 4]

RFC 7850                SDP 'proto' Registrations             April 2016   +--------+---------------------+-----------+   | Type   | SDP Name            | Reference |   +--------+---------------------+-----------+   | proto  | TCP/RTP/AVPF        |RFC 7850  |   |        |                     |           |   | proto  | TCP/RTP/SAVP        |RFC 7850  |   |        |                     |           |   | proto  | TCP/RTP/SAVPF       |RFC 7850  |   |        |                     |           |   | proto  | TCP/DTLS/RTP/SAVP   |RFC 7850  |   |        |                     |           |   | proto  | TCP/DTLS/RTP/SAVPF  |RFC 7850  |   |        |                     |           |   | proto  | TCP/TLS/RTP/AVP     |RFC 7850  |   |        |                     |           |   | proto  | TCP/TLS/RTP/AVPF    |RFC 7850  |   +--------+---------------------+-----------+6.  Security Considerations   The new "proto" identifiers registered by this document in the SDP   parameters registry maintained by IANA are primarily for use by the   offer/answer model of the Session Description Protocol [RFC3264] for   the negotiation and establishment of RTP-based media over the TCP   transport.  This specification doesn't introduce any additional   security considerations beyond those specified by the individual   transport protocols identified in the "proto" identifiers and those   detailed inSection 7 of [RFC4566].7.  References7.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <http://www.rfc-editor.org/info/rfc2119>.   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session              Description Protocol",RFC 4566, DOI 10.17487/RFC4566,              July 2006, <http://www.rfc-editor.org/info/rfc4566>.   [RFC4571]  Lazzaro, J., "Framing Real-time Transport Protocol (RTP)              and RTP Control Protocol (RTCP) Packets over Connection-              Oriented Transport",RFC 4571, DOI 10.17487/RFC4571, July              2006, <http://www.rfc-editor.org/info/rfc4571>.Nandakumar                   Standards Track                    [Page 5]

RFC 7850                SDP 'proto' Registrations             April 2016   [RFC4572]  Lennox, J., "Connection-Oriented Media Transport over the              Transport Layer Security (TLS) Protocol in the Session              Description Protocol (SDP)",RFC 4572,              DOI 10.17487/RFC4572, July 2006,              <http://www.rfc-editor.org/info/rfc4572>.   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment              (ICE): A Protocol for Network Address Translator (NAT)              Traversal for Offer/Answer Protocols",RFC 5245,              DOI 10.17487/RFC5245, April 2010,              <http://www.rfc-editor.org/info/rfc5245>.   [RFC5764]  McGrew, D. and E. Rescorla, "Datagram Transport Layer              Security (DTLS) Extension to Establish Keys for the Secure              Real-time Transport Protocol (SRTP)",RFC 5764,              DOI 10.17487/RFC5764, May 2010,              <http://www.rfc-editor.org/info/rfc5764>.   [RFC6544]  Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,              "TCP Candidates with Interactive Connectivity              Establishment (ICE)",RFC 6544, DOI 10.17487/RFC6544,              March 2012, <http://www.rfc-editor.org/info/rfc6544>.7.2.  Informative References   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model              with Session Description Protocol (SDP)",RFC 3264,              DOI 10.17487/RFC3264, June 2002,              <http://www.rfc-editor.org/info/rfc3264>.   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.              Jacobson, "RTP: A Transport Protocol for Real-Time              Applications", STD 64,RFC 3550, DOI 10.17487/RFC3550,              July 2003, <http://www.rfc-editor.org/info/rfc3550>.   [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.              Norrman, "The Secure Real-time Transport Protocol (SRTP)",RFC 3711, DOI 10.17487/RFC3711, March 2004,              <http://www.rfc-editor.org/info/rfc3711>.   [RFC4145]  Yon, D. and G. Camarillo, "TCP-Based Media Transport in              the Session Description Protocol (SDP)",RFC 4145,              DOI 10.17487/RFC4145, September 2005,              <http://www.rfc-editor.org/info/rfc4145>.Nandakumar                   Standards Track                    [Page 6]

RFC 7850                SDP 'proto' Registrations             April 2016   [RFC4585]  Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,              "Extended RTP Profile for Real-time Transport Control              Protocol (RTCP)-Based Feedback (RTP/AVPF)",RFC 4585,              DOI 10.17487/RFC4585, July 2006,              <http://www.rfc-editor.org/info/rfc4585>.   [RFC5124]  Ott, J. and E. Carrara, "Extended Secure RTP Profile for              Real-time Transport Control Protocol (RTCP)-Based Feedback              (RTP/SAVPF)",RFC 5124, DOI 10.17487/RFC5124, February              2008, <http://www.rfc-editor.org/info/rfc5124>.   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security              (TLS) Protocol Version 1.2",RFC 5246,              DOI 10.17487/RFC5246, August 2008,              <http://www.rfc-editor.org/info/rfc5246>.Acknowledgements   The author would like to thank Cullen Jennings, Alissa Cooper, Justin   Uberti, Mo Zanaty, Christer Holmberg, Jonathan Lennox, Flemming   Andreason, Roni Even, Ben Campbell, and Bo Burman for their reviews   and suggested improvements.   The author would also like to thank Adam Montville for the SecDir   review, Meral Shirazipour for the Gen-ART review, and Sarah Banks for   the OPS-Dir review.Author's Address   Suhas Nandakumar   Cisco Systems Inc   707 Tasman Drive   San Jose, CA  95134   United States   Email: snandaku@cisco.comNandakumar                   Standards Track                    [Page 7]