Session Description Protocol (SDP) Offer/Answer Procedures for Stream Control Transmission Protocol (SCTP) over Datagram Transport Layer Security (DTLS) Transport
RFC 8841

Document Type RFC - Proposed Standard (January 2021; No errata)
Authors Christer Holmberg  , Roman Shpount , Salvatore Loreto  , Gonzalo Camarillo 
Last updated 2021-01-18
Replaces draft-loreto-mmusic-sctp-sdp
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Internet Engineering Task Force (IETF)                       C. Holmberg
Request for Comments: 8841                                      Ericsson
Category: Standards Track                                     R. Shpount
ISSN: 2070-1721                                              TurboBridge
                                                               S. Loreto
                                                            G. Camarillo
                                                            January 2021

 Session Description Protocol (SDP) Offer/Answer Procedures for Stream
   Control Transmission Protocol (SCTP) over Datagram Transport Layer
                       Security (DTLS) Transport


   The Stream Control Transmission Protocol (SCTP) is a transport
   protocol used to establish associations between two endpoints.  RFC
   8261 specifies how SCTP can be used on top of the Datagram Transport
   Layer Security (DTLS) protocol, which is referred to as SCTP-over-

   This specification defines the following new Session Description
   Protocol (SDP) protocol identifiers (proto values): "UDP/DTLS/SCTP"
   and "TCP/DTLS/SCTP".  This specification also specifies how to use
   the new proto values with the SDP offer/answer mechanism for
   negotiating SCTP-over-DTLS associations.

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

Copyright Notice

   Copyright (c) 2021 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
   ( 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
   2.  Conventions
   3.  SCTP Terminology
   4.  SDP Media Descriptions
     4.1.  General
     4.2.  Protocol Identifiers
     4.3.  Media-Format Management
     4.4.  Syntax
       4.4.1.  General
       4.4.2.  SDP Media Description Values
     4.5.  Example
   5.  SDP "sctp-port" Attribute
     5.1.  General
     5.2.  Syntax
     5.3.  Mux Category
   6.  SDP "max-message-size" Attribute
     6.1.  General
     6.2.  Syntax
     6.3.  Mux Category
   7.  UDP/DTLS/SCTP Transport Realization
   8.  TCP/DTLS/SCTP Transport Realization
   9.  Association and Connection Management
     9.1.  General
     9.2.  SDP "sendrecv"/"sendonly"/"recvonly"/"inactive" Attributes
     9.3.  SCTP Association
     9.4.  DTLS Association (UDP/DTLS/SCTP and TCP/DTLS/SCTP)
     9.5.  TCP Connection (TCP/DTLS/SCTP)
   10. SDP Offer/Answer Procedures
     10.1.  General
     10.2.  Generating the Initial SDP Offer
     10.3.  Generating the SDP Answer
     10.4.  Offerer Processing of the SDP Answer
     10.5.  Modifying the Session
   11. Multihoming Considerations
   12. NAT Considerations
     12.1.  General
     12.2.  ICE Considerations
   13. Examples
     13.1.  Establishment of UDP/DTLS/SCTP Association
   14. Security Considerations
   15. IANA Considerations
     15.1.  New SDP Proto Values
     15.2.  New SDP Attributes
       15.2.1.  sctp-port
       15.2.2.  max-message-size
     15.3.  association-usage Name Registry
   16. References
     16.1.  Normative References
     16.2.  Informative References
   Authors' Addresses

1.  Introduction

   The Session Description Protocol (SDP) [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 and establishing TCP [RFC0793] streams.  "Connection-
   Oriented Media Transport over the Transport Layer Security (TLS)
   Protocol in the Session Description Protocol (SDP)" [RFC8122] extends
   [RFC4145] to describe TCP-based media streams that are protected
   using TLS.

   The Stream Control Transmission Protocol (SCTP) [RFC4960] is a
   reliable transport protocol used to transport data between two
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