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Versions: 00 draft-ietf-mediactrl-requirements

Mediactrl                                                       M. Dolly
Internet-Draft                                                 AT&T Labs
Intended status: Informational                                   R. Even
Expires: December 14, 2007                                       Polycom
                                                           June 12, 2007

               Media Server Control Protocol Requirements

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Copyright Notice

   Copyright (C) The IETF Trust (2007).


   This document addresses the communication between an application
   server and media server.  The current work in SIPPING and XCON
   working groups show these logical entities but do not address the
   physical decomposition and the protocol between the entities.

   This document presents the requirements from a media server control
   protocol (MCP) that enables an application server to use a media

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   server.  It will address the aspects of announcements, IVR and
   conferencing media services.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.1.  Media Control Requirements  . . . . . . . . . . . . . . . . 4
     3.2.  Media mixing Requirements . . . . . . . . . . . . . . . . . 6
     3.3.  IVR Requirements  . . . . . . . . . . . . . . . . . . . . . 6
     3.4.  Operational Requirements  . . . . . . . . . . . . . . . . . 7
   4.  IANA consideration  . . . . . . . . . . . . . . . . . . . . . . 7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   6.  Acknowledgment  . . . . . . . . . . . . . . . . . . . . . . . . 7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8
   Intellectual Property and Copyright Statements  . . . . . . . . . . 9

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1.  Introduction

   The IETF SIPPING conferencing framework RFC 4353[CARCH] presents an
   architecture that is built of several functional entities.  The
   framework document does not specify the protocols between the
   functional entities since it is considered out of scope.

   There is an interest to work on a protocol that will enable one
   physical entity that includes the conference/media policy server,
   notification server and the focus also known as Application server to
   interact with one or more physical entities, called Media Server,
   that serves as mixer or media server.

   The Media server may also be used for announcements and IVR
   (Interactive Voice Response) functions.

   The decomposition to a media server and application server is
   described in the media control framework document[mediactrl-fw].

   This document presents the requirements from a media server control
   protocol (MCP) that enables an application server to use a media
   server.  It will address the aspects of announcements, IVR and
   conferencing media services.

   The requirements are from the protocol and do not address the AS or
   MS functionality discussed in the media control framework.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC2119[RFC2119] and
   indicate requirement levels for compliant RTP implementations.

   The Media Server work uses, when appropriate, and expands on the
   terminology introduced in the SIP conferencing framework[CARCH] and
   XCON conferencing framework[xcon-framework].  The following
   additional terms are defined:

   Application Server (AS) - A functional entity that hosts one or more
   instances of a communications application.  The application server
   includes the conference policy server, the focus and the conference
   notification server as defined in [CARCH].  It can include also
   communication applications that use IVR or announcements services.

   Media Server (MS) - The media server includes the mixer as defined in
   [CARCH].  The media server source media streams for announcements, it

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   process media streams for functions like DTMF detection and
   transcoding.  The media server may also record media streams for
   supporting IVR functions like announcing participants

   Media Resource Broker (MRB) - A logical entity that is responsible
   for both collection of appropriate published Media Server (MS)
   information and supplying of appropriate MS information to consuming

   Notification - A notification is used when there is a need to report
   event related information from the MS to the AS.

   Request - A request is sent from the controlling entity, such as an
   Application Server, to another resource, such as a Media Server,
   asking that a particular type of operation be executed.

   Response - A response is used to signal information such as an
   acknowledgement or error code in reply to a previously issued

3.  Requirements

3.1.  Media Control Requirements

   The following are the media control requirements:

   REQ-MCP-01 -  The MS control protocol SHALL enable one or more
      Application Servers to control one or more media servers.

   REQ-MCP-02  The MS control protocol SHALL be independent from the
      transport protocol.

   REQ-MCP-03  The MS control protocol SHALL use a reliable transport

   REQ-MCP-04 -  The application scope of the protocol shall include
      Conferencing and Interactive Voice Response media services.

   Note: Though the protocol enables these services, the functionality
   is invoked through other mechanisms.

   REQ-MCP-05 -  Media types supported in the context of the
      applications shall include audio, tones, text and video.

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   REQ-MCP-06-  The MS control protocol should allow, but must not
      require, a media resource broker (MRB) or intermediate proxy to
      exist with the Application Server and Media Server.

   REQ-MCP-07 -  The solution MUST enable one control channel between an
      AS and MS, and SHOULD allow for the support of multiple channels.

   One control channel could control multiple sessions, but you could
   have multiple control channels controlling one or more sessions.

   REQ-MCP-8 -  On the MS control channel, there shall be requests to
      the MS, responses from the MS and notifications to the AS.

   REQ-MCP-9 -  SIP/SDP SHALL be used to establish and modify media
      connections to a Media Server.

   REQ-MCP-10 -  It should be possible to support a single conference
      spanning multiple Media Servers.

      Note: It is probable that spanning multiple MS can be accomplished
      by the AS and does not require anything in the protocol for the
      scenarios we have in mind.  However, the concern is that if this
      requirement is treated too lightly, one may end up with a protocol
      that precludes its support.

   REQ-MCP-11 -  It must be possible to split call legs individually or
      in groups away from a main conference on a given Media Server,
      without performing re-establishment of the call legs to the MS
      (e.g., for purposes such as performing IVR with a single call leg
      or creating sub-conferences, not for creating entirely new

   REQ-MCP-12 -  The MS control protocol should be extendable,
      facilitating forward and backward compatibility.

   REQ-MCP-13 -  The MS control protocol shall include security

   REQ-MCP-14 -  During session establishment, there shall be a
      capability to negotiate parameters that are associated with media

   REQ-MCP-15 -  The AS shall be able to define operations that the MS
      will perform on streams like mute and gain control.

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   REQ-MCP-16 -  The AS shall be able to instruct the MS to play a
      specific announcement.

   REQ-MCP-17 -  The AS shall be able to request the MS to create,
      delete, and manipulate a mixing, IVR or announcement session.

   REQ-MCP-18 -  The AS shall be able to instruct the MS to play
      announcements to a single user or to a conference mix.

   REQ-MCP-19 -  The MS control protocol SHOULD enable the AS to ask the
      MS for session summary report.

   REQ-MCP-20 -  The MS shall be able to notify the AS of events
      received in the media stream if requested by AS.  (Examples - STUN
      request, Flow Control, etc.)

3.2.  Media mixing Requirements

   REQ-MCP-21 -  The AS shall be able to define a conference mix.

   REQ-MCP-22 -  The AS may be able to define a separate mix for each

   REQ-MCP-23 -  The AS may be able to define a custom video layout
      built of rectangular sub windows.

   REQ-MCP-24 -  For video the AS shall be able to map a stream to a
      specific sub-window or to define to the MS how to decide which
      stream will go to each sub window.  The number of sub-windows will
      start from one.

   REQ-MCP-25 -  The MS shall be able to notify the AS who is the active

   REQ-MCP-26 -  The MS shall be able to inform the AS which layouts it

   REQ-MCP-27 -  The MS control protocol should enable the AS to
      instruct the MS to record a specific conference mix.

3.3.  IVR Requirements

   REQ-MCP-28 -  The AS shall be able to load one or more IVR script to
      the MS and receive the results.

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   REQ-MCP-29 -  The AS shall be able to mange the IVR session by
      sending announcements and receiving the response (e.g., DTMF).

   REQ-MCP-30 -  The AS should be able to instruct the MS to record a
      short participant stream and play it back to the conference.  This
      is not a recording requirement.

3.4.  Operational Requirements

   These requirements may be applicable to the MRB.

   REQ-MCP-31 -  The MS control protocol must allow the AS to audit the
      MS state, during an active session.

   REQ-MCP-32 -  The MS shall be able to inform the AS about its status
      during an active session.

4.  IANA consideration

   There are no IANA considerations.

5.  Security Considerations

   The protocol shall include security mechanisms.

6.  Acknowledgment

   would also like to acknowledge the work of Gary Munson from AT &T
   Labs and James Rafferty from Cantata who helped with drafting
   draft-dolly-xcon-mediacntrlframe-02 on which this work is based.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

7.2.  Informative References

   [CARCH]    Rosenberg, J., "A Framework for Conferencing with the
              Session Initiation Protocol (SIP)", RFC 4353,
              February 2006.

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              Melanchuk, T., "An Architectural Framework for Media
              Server Control", draft-melanchuk-mediactrl-framework-00
              (work in progress), June 2007.

              Barnes, M., "A Framework for Centralized Conferencing",
              draft-ietf-xcon-framework-08 (work in progress), May 2007.

Authors' Addresses

   Martin Dolly
   AT&T Labs
   200 Laurel Avenue
   Middletown, NJ  07748

   Email: mdolly@att.com

   Roni Even
   94 Derech Em Hamoshavot
   Petach Tikva  49130

   Email: roni.even@polycom.co.il

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Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

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