The WebSocket Protocol as a Transport for the Binary Floor Control Protocol (BFCP)
RFC 8857

Document Type RFC - Proposed Standard (January 2021; No errata)
Authors Victor Pascual  , Anton Roman  , Stephane Cazeaux  , Gonzalo Salgueiro  , Ram R 
Last updated 2021-01-19
Replaces draft-pascual-bfcpbis-bfcp-websocket
Stream Internet Engineering Task Force (IETF)
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IESG IESG state RFC 8857 (Proposed Standard)
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Internet Engineering Task Force (IETF)                        V. Pascual
Request for Comments: 8857                                         Nokia
Category: Standards Track                                       A. Román
ISSN: 2070-1721                                                   Quobis
                                                              S. Cazeaux
                                                            G. Salgueiro
                                                         R. Ravindranath
                                                            January 2021

   The WebSocket Protocol as a Transport for the Binary Floor Control
                            Protocol (BFCP)


   The WebSocket protocol enables two-way real-time communication
   between clients and servers.  This document specifies the use of
   Binary Floor Control Protocol (BFCP) as a new WebSocket subprotocol
   enabling a reliable transport mechanism between BFCP entities in new

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.  Terminology
     2.1.  Definitions
   3.  The WebSocket Protocol
   4.  The WebSocket BFCP Subprotocol
     4.1.  Handshake
     4.2.  BFCP Encoding
   5.  Transport Reliability
   6.  SDP Considerations
     6.1.  Transport Negotiation
     6.2.  SDP Media Attributes
   7.  SDP Offer/Answer Procedures
     7.1.  General
     7.2.  Example Usage of 'websocket-uri' SDP Attribute
   8.  Authentication
   9.  Security Considerations
   10. IANA Considerations
     10.1.  Registration of the WebSocket BFCP Subprotocol
     10.2.  Registration of the 'TCP/WS/BFCP' and 'TCP/WSS/BFCP' SDP
            "proto" Values
   11. References
     11.1.  Normative References
     11.2.  Informative References
   Authors' Addresses

1.  Introduction

   The WebSocket (WS) protocol [RFC6455] enables two-way message
   exchange between clients and servers on top of a persistent TCP
   connection, optionally secured with Transport Layer Security (TLS)
   [RFC8446].  The initial protocol handshake makes use of Hypertext
   Transfer Protocol (HTTP) [RFC7230] semantics, allowing the WebSocket
   protocol to reuse existing HTTP infrastructure.

   The Binary Floor Control Protocol (BFCP) is a protocol to coordinate
   access to shared resources in a conference.  It is defined in
   [RFC8855] and is used between floor participants and floor control
   servers, and between floor chairs (i.e., moderators) and floor
   control servers.

   Modern web browsers include a WebSocket client stack complying with
   the WebSocket API [WS-API] as specified by the W3C.  It is expected
   that other client applications (those running in personal computers
   and devices such as smartphones) will also make a WebSocket client
   stack available.  This document extends the applicability of
   [RFC8855] and [RFC8856] to enable the usage of BFCP in these

   The transport over which BFCP entities exchange messages depends on
   how the clients obtain information to contact the floor control
   server (e.g., using a Session Description Protocol (SDP) offer/answer
   exchange per [RFC8856] or the procedure described in RFC 5018
   [RFC5018]).  [RFC8855] defines two transports for BFCP: TCP and UDP.
   This specification defines a new WebSocket subprotocol (as defined in
   Section 1.9 of [RFC6455]) for transporting BFCP messages between a
   WebSocket client and server.  This subprotocol provides a reliable
   and boundary-preserving transport for BFCP when run on top of TCP.
   Since WebSocket provides a reliable transport, the extensions defined
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