Session Initiation Protocol (SIP) Session Mobility
RFC 5631

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Network Working Group                                         R. Shacham
Request for Comments: 5631                                H. Schulzrinne
Category: Informational                              Columbia University
                                                            S. Thakolsri
                                                             W. Kellerer
                                                        DoCoMo Euro-Labs
                                                            October 2009

           Session Initiation Protocol (SIP) Session Mobility

Abstract

   Session mobility is the transfer of media of an ongoing communication
   session from one device to another.  This document describes the
   basic approaches and shows the signaling and media flow examples for
   providing this service using the Session Initiation Protocol (SIP).
   Service discovery is essential to locate targets for session transfer
   and is discussed using the Service Location Protocol (SLP) as an
   example.  This document is an informational document.

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

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   document authors.  All rights reserved.

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   Without obtaining an adequate license from the person(s) controlling

Shacham, et al.              Informational                      [Page 1]
RFC 5631                  SIP Session Mobility              October 2009

   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Overview ........................................................3
   2. Requirements ....................................................4
   3. Roles of Entities ...............................................4
   4. Device Discovery ................................................5
   5. Session Mobility ................................................7
      5.1. Options for Session Mobility ...............................7
           5.1.1. Transfer and Retrieval ..............................7
           5.1.2. Whole and Split Transfer ............................7
           5.1.3. Transfer Modes ......................................8
                  5.1.3.1. Mobile Node Control (MNC) Mode .............8
                  5.1.3.2. Session Handoff (SH) Mode ..................8
           5.1.4. Types of Transferred Media ..........................8
      5.2. Addressing of Local Devices ................................9
      5.3. Mobile Node Control Mode ..................................10
           5.3.1. Transferring a Session to a Single Local Device ....10
                  5.3.1.1. RTP Media .................................10
                  5.3.1.2. MSRP Sessions .............................11
           5.3.2. Transfer to Multiple Devices .......................13
           5.3.3. Retrieval of a Session .............................16
      5.4. Session Handoff (SH) mode .................................16
           5.4.1. Transferring a Session to a Single Local Device ....16
           5.4.2. Retrieval of a Session .............................19
           5.4.3. Transfer to Multiple Devices .......................21
      5.5. Distributing Sessions for Incoming Call ...................23
      5.6. Use of ICE in Session Mobility ............................24
   6. Reconciling Device Capability Differences ......................25
      6.1. Codec Differences .........................................25
      6.2. Display Resolution and Bandwidth Differences ..............27
   7. Simultaneous Session Transfer ..................................27
   8. Session Termination ............................................28