WebRTC Data Channels
RFC 8831

Document Type RFC - Proposed Standard (January 2021; No errata)
Authors Randell Jesup  , Salvatore Loreto  , Michael Tüxen 
Last updated 2021-01-18
Replaces draft-jesup-rtcweb-data
Stream Internet Engineering Task Force (IETF)
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Stream WG state Submitted to IESG for Publication
Document shepherd Ted Hardie
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IESG IESG state RFC 8831 (Proposed Standard)
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IANA IANA review state Version Changed - Review Needed
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Internet Engineering Task Force (IETF)                          R. Jesup
Request for Comments: 8831                                       Mozilla
Category: Standards Track                                      S. Loreto
ISSN: 2070-1721                                                 Ericsson
                                                                M. Tüxen
                                         Münster Univ. of Appl. Sciences
                                                            January 2021

                          WebRTC Data Channels


   The WebRTC framework specifies protocol support for direct,
   interactive, rich communication using audio, video, and data between
   two peers' web browsers.  This document specifies the non-media data
   transport aspects of the WebRTC framework.  It provides an
   architectural overview of how the Stream Control Transmission
   Protocol (SCTP) is used in the WebRTC context as a generic transport
   service that allows web browsers to exchange generic data from peer
   to peer.

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
   (https://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
   2.  Conventions
   3.  Use Cases
     3.1.  Use Cases for Unreliable Data Channels
     3.2.  Use Cases for Reliable Data Channels
   4.  Requirements
   5.  SCTP over DTLS over UDP Considerations
   6.  The Usage of SCTP for Data Channels
     6.1.  SCTP Protocol Considerations
     6.2.  SCTP Association Management
     6.3.  SCTP Streams
     6.4.  Data Channel Definition
     6.5.  Opening a Data Channel
     6.6.  Transferring User Data on a Data Channel
     6.7.  Closing a Data Channel
   7.  Security Considerations
   8.  IANA Considerations
   9.  References
     9.1.  Normative References
     9.2.  Informative References
   Authors' Addresses

1.  Introduction

   In the WebRTC framework, communication between the parties consists
   of media (for example, audio and video) and non-media data.  Media is
   sent using the Secure Real-time Transport Protocol (SRTP) and is not
   specified further here.  Non-media data is handled by using the
   Stream Control Transmission Protocol (SCTP) [RFC4960] encapsulated in
   DTLS.  DTLS 1.0 is defined in [RFC4347]; the present latest version,
   DTLS 1.2, is defined in [RFC6347]; and an upcoming version, DTLS 1.3,
   is defined in [TLS-DTLS13].

                               |   SCTP   |
                               |   DTLS   |
                               | ICE/UDP  |

                       Figure 1: Basic Stack Diagram

   The encapsulation of SCTP over DTLS (see [RFC8261]) over ICE/UDP (see
   [RFC8445]) provides a NAT traversal solution together with
   confidentiality, source authentication, and integrity-protected
   transfers.  This data transport service operates in parallel to the
   SRTP media transports, and all of them can eventually share a single
   UDP port number.

   SCTP, as specified in [RFC4960] with the partial reliability
   extension (PR-SCTP) defined in [RFC3758] and the additional policies
   defined in [RFC7496], provides multiple streams natively with
   reliable, and the relevant partially reliable, delivery modes for
   user messages.  Using the reconfiguration extension defined in
   [RFC6525] allows an increase in the number of streams during the
   lifetime of an SCTP association and allows individual SCTP streams to
   be reset.  Using [RFC8260] allows the interleave of large messages to
   avoid monopolization and adds support for prioritizing SCTP streams.

   The remainder of this document is organized as follows: Sections 3
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