Session Signaling for Controlling Multiple Streams for Telepresence (CLUE)
RFC 8848

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Internet Engineering Task Force (IETF)                         R. Hanton
Request for Comments: 8848                                 Cisco Systems
Category: Experimental                                        P. Kyzivat
ISSN: 2070-1721                                                         
                                                                 L. Xiao
                                                Beijing Chuangshiyoulian
                                                               C. Groves
                                                            January 2021

  Session Signaling for Controlling Multiple Streams for Telepresence
                                 (CLUE)

Abstract

   This document is about Controlling Multiple Streams for Telepresence
   (CLUE) signaling.  It specifies how the CLUE protocol and the CLUE
   data channel are used in conjunction with each other and with
   existing signaling mechanisms, such as SIP and the Session
   Description Protocol (SDP), to produce a telepresence call.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  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).  Not
   all documents approved by the IESG are candidates for any level of
   Internet Standard; see 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
   https://www.rfc-editor.org/info/rfc8848.

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.  Terminology
   3.  Media Feature Tag Definition
   4.  SDP Grouping Framework CLUE Extension Semantics
     4.1.  General
     4.2.  The CLUE Data Channel and the CLUE Grouping Semantic
     4.3.  CLUE-Controlled Media and the CLUE Grouping Semantic
     4.4.  SDP Semantics for CLUE-Controlled Media
       4.4.1.  Signaling CLUE Encodings
         4.4.1.1.  Referencing Encodings in the CLUE Protocol
       4.4.2.  Negotiating Receipt of CLUE Capture Encodings in SDP
     4.5.  SDP Offer/Answer Procedures
       4.5.1.  Generating the Initial Offer
       4.5.2.  Generating the Answer
         4.5.2.1.  Negotiating Use of CLUE and the CLUE Data Channel
         4.5.2.2.  Negotiating CLUE-Controlled Media
         4.5.2.3.  Negotiating Non-CLUE-controlled Media
       4.5.3.  Processing the Initial Offer/Answer Negotiation
         4.5.3.1.  Successful CLUE Negotiation
         4.5.3.2.  CLUE Negotiation Failure
       4.5.4.  Modifying the Session
         4.5.4.1.  Adding and Removing CLUE-Controlled Media
         4.5.4.2.  Enabling CLUE Mid-Call
         4.5.4.3.  Disabling CLUE Mid-Call
         4.5.4.4.  CLUE Protocol Failure Mid-Call
   5.  Interaction of the CLUE Protocol and SDP Negotiations
     5.1.  Independence of SDP and CLUE Negotiation
     5.2.  Constraints on Sending Media
     5.3.  Recommendations for Operating with Non-atomic Operations
   6.  Interaction of the CLUE Protocol and RTP/RTCP CaptureID
     6.1.  CaptureID Reception during MCC Redefinition
   7.  Multiplexing of CLUE-Controlled Media Using BUNDLE
     7.1.  Overview
     7.2.  Usage of BUNDLE with CLUE
       7.2.1.  Generating the Initial Offer
       7.2.2.  Multiplexing of the Data Channel and RTP Media
   8.  Example: A Call between Two CLUE-Capable Endpoints
   9.  Example: A Call between a CLUE-Capable and Non-CLUE Endpoint
   10. IANA Considerations
     10.1.  New SDP Grouping Framework Attribute
     10.2.  New SIP Media Feature Tag
   11. Security Considerations
   12. References
     12.1.  Normative References
     12.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   To enable devices to participate in a telepresence call, where they
   select the sources they wish to view, receive those media sources,
   and display them in an optimal fashion, Controlling Multiple Streams
   for Telepresence (CLUE) employs two principal and interrelated