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rfc:rfc6064

Internet Engineering Task Force (IETF) M. Westerlund Request for Comments: 6064 P. Frojdh Category: Informational Ericsson ISSN: 2070-1721 January 2011

 SDP and RTSP Extensions Defined for 3GPP Packet-Switched Streaming
         Service and Multimedia Broadcast/Multicast Service

Abstract

 The Packet-switched Streaming Service (PSS) and the Multimedia
 Broadcast/Multicast Service (MBMS) defined by 3GPP use the Session
 Description Protocol (SDP) and Real Time Streaming Protocol (RTSP)
 with some extensions.  This document provides information about these
 extensions and registers the RTSP and SDP extensions with IANA.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 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 a candidate for any level of Internet
 Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6064.

Copyright Notice

 Copyright (c) 2011 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
 (http://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.

Westerlund & Frojdh Informational [Page 1] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  4
 2.  Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
 3.  Applicability Statement  . . . . . . . . . . . . . . . . . . .  5
 4.  PSS SDP Extensions . . . . . . . . . . . . . . . . . . . . . .  5
   4.1.  Video Buffering Attributes . . . . . . . . . . . . . . . .  5
   4.2.  Video Frame Size Attribute . . . . . . . . . . . . . . . .  6
   4.3.  Integrity-Protection Configuration Attributes  . . . . . .  6
   4.4.  The Alternative Attributes . . . . . . . . . . . . . . . .  7
   4.5.  Adaptation Attribute . . . . . . . . . . . . . . . . . . .  7
   4.6.  Quality of Experience Attribute  . . . . . . . . . . . . .  7
   4.7.  Asset Information Attribute  . . . . . . . . . . . . . . .  8
 5.  MBMS SDP Extensions  . . . . . . . . . . . . . . . . . . . . .  8
   5.1.  MBMS Bearer Mode Declaration Attribute . . . . . . . . . .  8
   5.2.  FEC Flow ID Attribute  . . . . . . . . . . . . . . . . . .  8
   5.3.  MBMS Repair Attribute  . . . . . . . . . . . . . . . . . .  8
   5.4.  SDP Protocol Identifiers for FEC . . . . . . . . . . . . .  8
     5.4.1.  RTP Protocol Identifiers . . . . . . . . . . . . . . .  9
     5.4.2.  FEC Repair Data Identifier . . . . . . . . . . . . . .  9
   5.5.  Video Buffering Attribute  . . . . . . . . . . . . . . . .  9
 6.  SDP Offer/Answer Consideration . . . . . . . . . . . . . . . .  9
 7.  PSS RTSP Extensions  . . . . . . . . . . . . . . . . . . . . . 10
   7.1.  3GPP-Link-Char Header  . . . . . . . . . . . . . . . . . . 10
   7.2.  3GPP-Adaptation Header . . . . . . . . . . . . . . . . . . 10
   7.3.  3GPP-QoE-Metrics Header  . . . . . . . . . . . . . . . . . 10
   7.4.  3GPP-QoE-Feedback Header . . . . . . . . . . . . . . . . . 11
   7.5.  Video Buffer Headers . . . . . . . . . . . . . . . . . . . 11
   7.6.  Integrity Protection . . . . . . . . . . . . . . . . . . . 11
   7.7.  RTSP URI Extension . . . . . . . . . . . . . . . . . . . . 11
   7.8.  Fast Start-Up and Content Switching  . . . . . . . . . . . 12
 8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   8.1.  SDP Registrations  . . . . . . . . . . . . . . . . . . . . 12
   8.2.  RTSP Registrations . . . . . . . . . . . . . . . . . . . . 17
 9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
   10.1. Normative References . . . . . . . . . . . . . . . . . . . 20
   10.2. Informative References . . . . . . . . . . . . . . . . . . 21

Westerlund & Frojdh Informational [Page 2] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

1. Introduction

 3GPP has specified the Packet-switched Streaming Service (PSS) that
 uses both RTSP [RFC2326] and SDP [RFC4566].  The service is specified
 in technical specifications TS 26.233 [PSS-233] and TS 26.234
 [PSS-234] in Release 4 and subsequent releases.  The basic service
 defined in Release 4 is enhanced in Release 5 with capability
 exchange, and in Release 6 with a number of features, such as
 adaptation, digital rights management (DRM), progressive download, as
 well as a streaming server file format defined in [PSS-3GP].  Fast
 start-up and content switching are addressed in Release 7.
 3GPP has also specified the Multimedia Broadcast/Multicast Service
 (MBMS) that uses SDP.  The IP-layer protocols used by this service
 are specified in technical specification TS 26.346 Release 6 [MBMS].
 Release 7 extends the MBMS User Service to also work with unicast
 bearers for interactive and streaming traffic classes.
 In the process of defining these services, there has occasionally
 been a need to extend both SDP and RTSP functionalities.  These
 extensions have mostly been in the form of SDP attributes and RTSP
 headers and option tags. 3GPP uses the name "feature tags" (like RTSP
 2.0 for what RTSP 1.0 calls "option tags"); "option tag" is the name
 that will be used in this document.  The purpose of this
 informational document is to register these SDP and RTSP extensions,
 in order to avoid future conflicts, and also to raise the awareness
 of their existence within IETF.
 In Section 5.4, this document defines three SDP protocol identifiers
 used in MBMS to enable the usage of block-based FEC.  The SDP
 protocol identifiers require an RFC to be defined and registered.  As
 this is an RFC from the IETF stream, any semantic change will require
 a new IETF-approved RFC.  The other SDP and RTSP extensions
 registered by this document are not normatively defined in this
 document.  Instead, the normative definitions are referenced by the
 registrations. 3GPP can update the normative definition in future
 versions of their specifications.  However, to ensure that such a
 change is visible in the IETF, at minimum, IANA should be notified
 and the reference to the 3GPP specification updated, and preferably
 an updated version of this RFC published.
 The document begins with two sections presenting the SDP extensions
 for PSS and MBMS, respectively.  They are followed by a section
 noting that offer/answer considerations are not applicable here.  The
 subsequent section presents the extensions of RTSP for PSS.  The IANA
 registration of SDP attributes and protocol identifiers is given in

Westerlund & Frojdh Informational [Page 3] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

 Section 8.1, and the RTSP headers and option tags in Section 8.2.
 For normative descriptions of all SDP and RTSP extensions, we refer
 to TS 26.234 [PSS-234] and TS 26.346 [MBMS].

1.1. Requirements Language

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [RFC2119].

2. Glossary

 3GP:     3GPP file format, a multimedia file format based on the ISO
          base media file format, existing in different profiles
          intended for multimedia messages, direct playback on
          clients, progressive download, usage on servers to deliver
          on-demand multimedia sessions in PSS, or servers sending
          MBMS sessions.
 3GPP:    Third Generation Partnership Project; see
          http://www.3gpp.org for more information about this
          organization.
 FEC:     Forward Error Correction
 MBMS:    Multimedia Broadcast/Multicast Service, a service defined by
          3GPP that utilizes broadcast or multicast technology in
          combination with unicast for delivery of a wide range of
          content to mobile terminals.
 PSS:     Packet-switched Streaming Service, a unicast-based streaming
          service for delivery of on-demand or live streaming
          multimedia content to mobile terminals.
 RTSP:    Real Time Streaming Protocol; see [RFC2326].
 SDP:     Session Description Protocol; see [RFC4566].
 SRTP:    Secure Real-time Transport Protocol; see [RFC3711].
 QoE:     Quality of Experience, the quality level of the user
          experience of a service.  In PSS, this is estimated by a
          combination of application-level metrics.
 QoS:     Quality of Service, the quality (properties) that the
          network provides toward the upper-layer service.

Westerlund & Frojdh Informational [Page 4] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

3. Applicability Statement

 This document describes 3GPP-defined extensions to SDP [RFC4566] and
 RTSP [RFC2326] and registers attributes that are normatively defined
 in 3GPP technical specifications 26.234, 26.244, and 26.346, up to
 the referenced versions of the respective documents.
 The SDP and RTSP extensions have only been defined for usage with the
 3GPP service in mind.  The applicability for usage outside of these
 services has not been considered nor addressed.  Usage of these
 attributes in other contexts may require further definitions or
 clarifications.  For example, all SDP attributes lack offer/answer
 usage rules [RFC3264], which currently makes it impossible to use
 them with offer/answer.  Please note that change control of these SDP
 and RTSP extensions belongs to 3GPP.

4. PSS SDP Extensions

 The PSS specification [PSS-234] defines a number of different SDP
 attributes for different purposes.  They are listed below, grouped by
 their purpose.  The text is intentionally not specific enough to
 allow implementation from this document.  The normative definition is
 in the 3GPP technical specification cited.

4.1. Video Buffering Attributes

 The following attributes are used to provide parameters for the video
 buffer model provided in Annex G and Section 5.3.3.2 of [PSS-234].
 The attributes were defined in Release 5 as "X-" attributes and, at
 the time, were not considered for registration.  In hindsight,
 however, they should not have been "X-" attributes, and they should
 have been registered, as the registration rules of SDP [RFC4566]
 point out.  Changing their names today is impossible due to the
 deployed base of millions of mobile handsets supporting PSS, and
 therefore they are registered in their current form.
 All attributes are defined at media level.
 o  The "a=X-predecbufsize" attribute provides the size of the pre-
    decoder buffer in bytes.
 o  The "a=X-initpredecbufperiod" attribute provides the time during
    which a receiver should initially buffer, in 90 kHz ticks, before
    starting to consume the data in the buffer in order to ensure that
    underflow does not occur, assuming correct data delivery.

Westerlund & Frojdh Informational [Page 5] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

 o  The "a=X-initpostdecbufperiod" attribute provides the initial
    buffering period, in 90 kHz ticks, for the post-decoder buffer
    present in H.263 and MPEG-4 Visual.
 o  The "a=X-decbyterate" attribute indicates the maximum peak byte-
    decoding rate used in the verification of the Annex G buffer model
    expressed in bytes per second.
 o  The "a=3gpp-videopostdecbufsize" attribute is used to indicate the
    value used in determining the H.264 video post-decoder buffer
    size.
 Note that complete descriptions of these attributes can be found in
 Section 5.3.3.2 of [PSS-234].

4.2. Video Frame Size Attribute

 This media-level attribute provides the receiver with the largest
 picture size that a specific H.263 payload type will carry within the
 session.  The attribute has the following form (see Section 5.3.3.2
 of [PSS-234]):
 "a=framesize:<payload type number> <width>-<height>"

4.3. Integrity-Protection Configuration Attributes

 These attributes are all used to configure the integrity-protection
 mechanism defined in Annex K (Sections K.2.2.1, K.2.2.2, and K.2.2.3)
 of [PSS-234].
 o  The session-level attribute "a=3GPP-Integrity-Key" carries the
    integrity key used to derive SRTP master keys for integrity
    protection.  The key is protected in different ways depending on a
    method identifier.  When using Open Mobile Alliance (OMA) DRM key
    management, the key is encrypted using AES [AES] before it is
    base64 encoded [RFC4648].
 o  The media-level attribute "a=3GPP-SRTP-Config" is used to
    configure SRTP for integrity protection and contains an integrity
    nonce, a key salt used in deriving the SRTP master key from the
    integrity key, and any SRTP configuration parameters, such as the
    integrity tag length.
 o  The session-level attribute "a=3GPP-SDP-Auth" is used to carry an
    authentication tag calculated over certain parts of the SDP to
    prevent manipulation of the security attributes.

Westerlund & Frojdh Informational [Page 6] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

4.4. The Alternative Attributes

 Two media-level and one session-level attributes are used in a
 mechanism for providing alternative SDP lines.  One or more SDP lines
 at media level can be replaced, if desired, by alternatives.  The
 mechanism is backwards compatible in the way that a receiver that
 does not support the attributes will get the default configuration.
 The different alternatives can be grouped using different attributes
 that can be specified hierarchically with a top and a lower level.
 3GPP Release 6 supports grouping based on bit-rate, according to the
 SDP bandwidth modifiers AS [RFC4566] and TIAS [RFC3890], and
 language.
 The SDP attributes (see Sections 5.3.3.3 and 5.3.3.4 of [PSS-234])
 are:
 o  The media-level attribute "a=alt:<id>:<SDP-Line>" carries any SDP
    line and an alternative identifier.
 o  The media-level attribute "a=alt-default-id:<id>" identifies the
    default configuration to be used in groupings.
 o  The session-level attribute "a=alt-group" is used to group
    different recommended media alternatives.  This allows providing
    aggregated properties for the whole group according to the
    grouping type.  Language and bit-rate are two defined grouping
    types.

4.5. Adaptation Attribute

 The media-level SDP attribute "a=3GPP-Adaptation-Support" (see
 Section 5.3.3.5 in [PSS-234]) is defined as part of the negotiation
 procedure of the PSS adaptation mechanism.  The attribute carries a
 single value indicating how often the RTCP "Next Application Data
 Unit" (NADU) APP packet shall be included in sent RTCP compound
 packets.  The adaptation mechanism allows the client to provide the
 server with information on the available transmission bit-rate and
 receiver buffer status.

4.6. Quality of Experience Attribute

 The session- and media-level attribute "a=3GPP-QoE-Metrics" (see
 Section 5.3.3.6 of [PSS-234]) is used to negotiate the usage of the
 QoE metrics.  The included parameters indicate which metrics should
 be used, over which duration there should be measurements, and how
 often reports should be sent.

Westerlund & Frojdh Informational [Page 7] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

4.7. Asset Information Attribute

 The session- and media-level attribute "a=3GPP-Asset-Information"
 (see Section 5.3.3.7 of [PSS-234]) can exist in multiple instances in
 a description and describes different types of asset information.
 The different asset classes defined in Release 6 are Title,
 Description, Copyright, Performer, Author, Genre, Rating,
 Classification, Keywords, Location, Album, and Recording Year.  The
 different assets are described with a base64-encoded asset box from
 the 3GP file format [PSS-3GP].

5. MBMS SDP Extensions

 The MBMS specification [MBMS] defines a number of different SDP
 attributes for different purposes.  They are informatively listed
 below.

5.1. MBMS Bearer Mode Declaration Attribute

 The session- and media-level attribute "a=mbms-mode" (see Section
 7.3.2.7 of [MBMS]) is used to describe MBMS broadcast mode media.
 The attribute may be used at the session level to set the default for
 all media and at the media level to specify differences between
 media.  However, the attribute is never used at the session level
 when the session includes MBMS multicast mode media, nor at the media
 level to describe MBMS multicast mode media.

5.2. FEC Flow ID Attribute

 The media-level attribute "a=mbms-flowid" (see Section 8.3.1.9 of
 [MBMS]) maps one or more FEC source block flow IDs to their
 corresponding destination IP addresses and UDP port numbers.  It is
 present in each SDP media block for repair packet streams.

5.3. MBMS Repair Attribute

 The session- and media-level attribute "a=mbms-repair" (see Section
 8.3.1.8 of [MBMS]) is used to provide FEC repair packets with non-FEC
 specific parameters.  For Release 6, one such parameter is defined to
 specify the required minimum receiver buffer time.

5.4. SDP Protocol Identifiers for FEC

 MBMS defines a mechanism to provide block-based FEC for UDP-based
 traffic.  This solution uses the SDP protocol "proto" identifier to
 identify the media streams that use the FEC shim layer.  The media

Westerlund & Frojdh Informational [Page 8] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

 streams may be either source streams or repair streams.  As required
 by SDP [RFC4566], these protocol identifiers are normatively defined
 in this document in accordance with their usage specified by 3GPP.

5.4.1. RTP Protocol Identifiers

 For FEC-protected RTP streams, the following two "proto" identifiers
 are defined:
 o  UDP/MBMS-FEC/RTP/AVP
 o  UDP/MBMS-FEC/RTP/SAVP
 They indicate the usage of UDP [RFC0768] with MBMS FEC source packet
 formats, as defined in Section 8.2.2.4 of [MBMS], that transport RTP
 packets in accordance with the AVP [RFC3551] or SAVP (Secure RTP)
 [RFC3711] profiles, respectively.  These protocol identifiers SHALL
 use the media formats ("fmt") namespace rules that are used for RTP/
 AVP and RTP/SAVP, respectively.

5.4.2. FEC Repair Data Identifier

 A media stream carrying MBMS FEC repair information over UDP requires
 its own "proto" identifier.  Protocol identifier "UDP/MBMS-REPAIR"
 identifies the FEC repair packet containing the protocol combination
 of UDP [RFC0768], FEC repair payload ID, and repair symbols as
 specified in Section 8.2.2.5 of [MBMS].  The "fmt" namespace is not
 used and SHALL be set to "*".

5.5. Video Buffering Attribute

 The PSS media-level buffer attribute "a=X-initpredecbufperiod" (see
 Section 4.1) that specifies an initial buffering time is also used
 for MBMS in Release 7.  It is mainly intended for video streams, but
 may be used for other media types as well (see Section 8.3.1.1 of
 [MBMS]).

6. SDP Offer/Answer Consideration

 The usage of the SDP attributes in an offer/answer [RFC3264] context
 is not defined.  These SDP attributes are defined for use in a
 declarative context, and for PSS specifically in the RTSP [RFC2326]
 context.

Westerlund & Frojdh Informational [Page 9] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

7. PSS RTSP Extensions

 The RTSP extensions for PSS consist of a number of new RTSP headers
 and option tags and a narrowing of URI usage in regards to 3GP files.
 The headers and option tags are informatively described here; see
 [PSS-234] for the normative declaration.

7.1. 3GPP-Link-Char Header

 The "3GPP-Link-Char" header (see Section 5.3.2.1 of [PSS-234]) is
 used by clients to provide the server with QoS information about the
 wireless link it is currently using.  The header can be used to
 provide the server with three different QoS parameters:
 o  Guaranteed Bandwidth
 o  Maximum Bandwidth
 o  Maximum Transfer Delay
 The header may be included in RTSP requests using either of the
 methods SETUP, PLAY, OPTIONS, or SET_PARAMETER.

7.2. 3GPP-Adaptation Header

 The "3GPP-Adaptation" header (see Section 5.3.2.2 of [PSS-234]) is
 used by the client to provide the server with adaptation-related
 parameters and to indicate support of the adaptation function.  The
 header carries the resource identification as a URI, the client's
 buffer size, and the desired target time.
 The header may be included in requests using the methods SETUP, PLAY,
 OPTIONS, and SET_PARAMETER.  The response to a request using this
 method shall include this header.

7.3. 3GPP-QoE-Metrics Header

 The "3GPP-QoE-Metrics" header (see Section 5.3.2.3.1 of [PSS-234]) is
 used to negotiate the usage of the QoE metrics (see Section 11 of
 [PSS-234]).
 The header may be included in requests and responses using the SETUP,
 SET_PARAMETER, OPTIONS, or PLAY method.

Westerlund & Frojdh Informational [Page 10] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

7.4. 3GPP-QoE-Feedback Header

 The "3GPP-QoE-Feedback" header (see Section 5.3.2.3.2 of [PSS-234])
 is used to carry QoE metrics from the client to the server when it
 reports, which happens either during or at the end of the media
 delivery.
 The header may be included in requests using the SET_PARAMETER,
 PAUSE, or TEARDOWN method.

7.5. Video Buffer Headers

 PSS uses several headers to provide the client with the different
 buffer parameters.  They provide the buffer status at the point of a
 stream from which a PLAY request plays.  These headers may only be
 used in PLAY responses.  See Section 5.3.2.4 and Annex G of [PSS-234]
 for normative definitions.
 The three "x-" headers were defined in 3GPP Release 5.  When it was
 realized that they should not have been given "x-" names, it was too
 late to rename them due to deployment.
 The RTSP headers are:
 o  x-predecbufsize
 o  x-initpredecbufperiod
 o  x-initpostdecbufperiod
 o  3gpp-videopostdecbufsize

7.6. Integrity Protection

 The integrity-protection mechanism defined in PSS Annex K uses the
 "3GPP-Freshness-Token" RTSP header (see Section K.2.2.4 of [PSS-234])
 to carry a freshness token in DESCRIBE requests.

7.7. RTSP URI Extension

 The PSS specification also defines syntax for referencing tracks
 within the 3GP file format [PSS-3GP].  The 3GP format is based on the
 ISO base media file format and is defined in several different
 profiles, including a streaming-server profile, in Release 6.

Westerlund & Frojdh Informational [Page 11] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

 This syntax is fully contained within the generic URI syntax defined
 for RTSP URIs.  It is only a syntax restriction that server
 manufacturers follow to allow clients or proxies to understand what
 encodes the track number in the URI.  This is provided for
 information only.
 To identify a track within a 3GP file, the last URI segment has to
 contain a structure that is <alpha string>=<track nr>.  (See Section
 5.3.3.1 of [PSS-234].)

7.8. Fast Start-Up and Content Switching

 Release 7 of PSS defines a number of extensions in terms of headers
 and option tags (see Section 5.5 of [PSS-234]) for support of fast
 start-up and switching of content for on-demand and live applications
 built on top of PSS.  Clients are enabled to reuse the existing RTSP
 control session and RTP resources while switching to new content.
 The RTSP headers are:
 o  Switch-Stream
 o  SDP-Requested
 o  Pipelined-Requests
 The RTSP option tags are:
 o  3gpp-pipelined
 o  3gpp-switch
 o  3gpp-switch-req-sdp
 o  3gpp-switch-stream

8. IANA Considerations

8.1. SDP Registrations

 IANA has registered the SDP attributes listed below in the "Session
 Description Protocol (SDP) Parameters" registry available from
 http://www.iana.org/.
 The contact person for this registration is Magnus Westerlund (email:
 magnus.westerlund@ericsson.com; phone: +46 8 719 0000).

Westerlund & Frojdh Informational [Page 12] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

SDP Protocol Identifiers ("proto"):
   Name:               UDP/MBMS-FEC/RTP/AVP
   Long form:          3GPP MBMS FEC-protected RTP/AVP over UDP
   Type of name:       proto
   Purpose:            3GPP MBMS defines a mechanism to provide block-
                       based FEC for UDP-based traffic.  This solution
                       uses the SDP protocol "proto" identifier to
                       identify the media streams that use the FEC
                       shim layer.  This protocol identifier indicates
                       that the FEC-protected data is RTP using the
                       AVP profile.
   Reference:          RFC 6064, 3GPP TS 26.346
   Name:               UDP/MBMS-FEC/RTP/SAVP
   Long form:          3GPP MBMS FEC-protected RTP/SAVP over UDP
   Type of name:       proto
   Purpose:            3GPP MBMS defines a mechanism to provide block-
                       based FEC for UDP-based traffic.  This solution
                       uses the SDP protocol "proto" identifier to
                       identify the media streams that use the FEC
                       shim layer.  This protocol identifier indicates
                       that the FEC-protected data is RTP using the
                       Secure AVP profile (SAVP).
   Reference:          RFC 6064, 3GPP TS 26.346
   Name:               UDP/MBMS-REPAIR
   Long form:          3GPP MBMS FEC repair symbols over UDP
   Type of name:       proto
   Purpose:            3GPP MBMS defines a mechanism to provide block-
                       based FEC for UDP-based traffic.  This solution
                       uses the SDP protocol "proto" identifier to
                       identify the media streams that use the FEC
                       shim layer.  This protocol identifier indicates
                       that the FEC repair data is sent over UDP.
   Reference:          RFC 6064, 3GPP TS 26.346
 SDP Attribute ("att-field"):
    Attribute name:     X-predecbufsize
    Long form:          Pre-decoder buffer size
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.1
    Reference:          3GPP TS 26.234, Section 5.3.3.2
    Values:             See Reference

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    Attribute name:     X-initpredecbufperiod
    Long form:          Pre-decoder initial buffering period
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.1
    Reference:          3GPP TS 26.234, Section 5.3.3.2
    Values:             See Reference
    Attribute name:     X-initpostdecbufperiod
    Long form:          Post-decoder initial buffering period
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.1
    Reference:          3GPP TS 26.234, Section 5.3.3.2
    Values:             See Reference
    Attribute name:     X-decbyterate
    Long form:          Peak decoding rate in bytes per second
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.1
    Reference:          3GPP TS 26.234, Section 5.3.3.2
    Values:             See Reference
    Attribute name:     3gpp-videopostdecbufsize
    Long form:          Post decoder buffer size
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.1
    Reference:          3GPP TS 26.234, Section 5.3.3.2
    Values:             See Reference
    Attribute name:     framesize
    Long form:          Maximum Video Frame Size
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.2
    Reference:          3GPP TS 26.234, Section 5.3.3.2
    Values:             See Reference

Westerlund & Frojdh Informational [Page 14] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

    Attribute name:     3GPP-Integrity-Key
    Long form:          3GPP DRM Integrity Key
    Type of name:       att-field
    Type of attribute:  Session level only
    Subject to charset: No
    Purpose:            See Section 4.3
    Reference:          3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.1
    Values:             See Reference
    Attribute name:     3GPP-SRTP-Config
    Long form:          3GPP DRM SRTP Configuration
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.3
    Reference:          3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.2
    Values:             See Reference
    Attribute name:     3GPP-SDP-Auth
    Long form:          3GPP DRM Integrity SDP Authentication
    Type of name:       att-field
    Type of attribute:  Session level only
    Subject to charset: No
    Purpose:            See Section 4.3
    Reference:          3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.3
    Values:             See Reference
    Attribute name:     alt
    Long form:          Alternative SDP line
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.4
    Reference:          3GPP TS 26.234, Section 5.3.3.3
    Values:             See Reference
    Attribute name:     alt-default-id
    Long form:          Default alternative ID
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.4
    Reference:          3GPP TS 26.234, Section 5.3.3.3
    Values:             See Reference

Westerlund & Frojdh Informational [Page 15] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

    Attribute name:     alt-group
    Long form:          Grouping of SDP Line alternatives
    Type of name:       att-field
    Type of attribute:  Session level only
    Subject to charset: No
    Purpose:            See Section 4.4
    Reference:          3GPP TS 26.234, Section 5.3.3.4
    Values:             See Reference
    Attribute name:     3GPP-Adaptation-Support
    Long form:          3GPP Adaptation Support
    Type of name:       att-field
    Type of attribute:  Media level only
    Subject to charset: No
    Purpose:            See Section 4.5
    Reference:          3GPP TS 26.234, Section 5.3.3.5
    Values:             See Reference
    Attribute name:     3GPP-QoE-Metrics
    Long form:          3GPP Quality of Experience Metrics
    Type of name:       att-field
    Type of attribute:  Session and Media level
    Subject to charset: No
    Purpose:            See Section 4.6
    Reference:          3GPP TS 26.234, Section 5.3.3.6
    Values:             See Reference
    Attribute name:     3GPP-Asset-Information
    Long form:          3GPP Asset Information
    Type of name:       att-field
    Type of attribute:  Session and Media level
    Subject to charset: No
    Purpose:            See Section 4.7
    Reference:          3GPP TS 26.234, Section 5.3.3.7
    Values:             See Reference
    Attribute name:     mbms-mode
    Long form:          MBMS Bearer Mode Declaration
    Type of name:       att-field
    Type of attribute:  Session and Media level
    Subject to charset: No
    Purpose:            See Section 5.1
    Reference:          3GPP TS 26.346, Section 7.3.2.7
    Values:             See Reference

Westerlund & Frojdh Informational [Page 16] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

    Attribute name:     mbms-flowid
    Long form:          FEC Flow ID
    Type of name:       att-field
    Type of attribute:  Media level
    Subject to charset: No
    Purpose:            See Section 5.2
    Reference:          3GPP TS 26.346, Section 8.3.1.9
    Values:             See Reference
    Attribute name:     mbms-repair
    Long form:          MBMS Repair
    Type of name:       att-field
    Type of attribute:  Session and Media level
    Subject to charset: No
    Purpose:            See Section 5.3
    Reference:          3GPP TS 26.346, Section 8.3.1.8
    Values:             See Reference

8.2. RTSP Registrations

 IANA has registered the RTSP headers listed below in the RTSP/1.0
 Headers table of the "Real Time Streaming Protocol (RTSP)/1.0
 Parameters" registry available from http://www.iana.org/.
 Note: This registry requires a Standards document, preferably an IETF
 RFC.  The document that defines the registered headers below is a
 technical standards document from 3GPP, although the request for
 registration is submitted using this document to achieve further
 information spreading within IETF.
 The contact person for this registration is Magnus Westerlund (email:
 magnus.westerlund@ericsson.com; phone: +46 8 719 0000).
    Header Name:     3GPP-Freshness-Token
    Purpose:         See Section K.2 of 3GPP TS 26.234
    Methods:         DESCRIBE Requests
    Reference:       Section K.2.2.4 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     3GPP-Link-Char
    Purpose:         See Section 5.3.2.1 of 3GPP TS 26.234
    Methods:         SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests
    Reference:       Section 5.3.2.1 of 3GPP TS 26.234
    Values:          See Reference

Westerlund & Frojdh Informational [Page 17] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

    Header Name:     3GPP-Adaptation
    Purpose:         See Section 5.3.2.2 of 3GPP TS 26.234
    Methods:         SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests
                     and Responses
    Reference:       Section 5.3.2.2 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     3GPP-QoE-Metrics
    Purpose:         See Section 5.3.2.3.1 of 3GPP TS 26.234
    Methods:         SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests
                     and Responses
    Reference:       Section 5.3.2.3.1 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     3GPP-QoE-Feedback
    Purpose:         See Section 5.3.2.3.2 of 3GPP TS 26.234
    Methods:         SET_PARAMETER, PAUSE, or TEARDOWN Requests
    Reference:       Section 5.3.2.3.2 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     Switch-Stream
    Purpose:         See Section 5.5.4.2 of 3GPP TS 26.234
    Methods:         PLAY Requests and Responses
    Reference:       Section 5.5.4.2 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     SDP-Requested
    Purpose:         See Section 5.5.4.4 of 3GPP TS 26.234
    Methods:         PLAY Requests
    Reference:       Section 5.5.4.4 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     Pipelined-Requests
    Purpose:         See Section 5.5.3 of 3GPP TS 26.234
    Methods:         SETUP and PLAY Requests
    Reference:       Section 5.5.3 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     x-predecbufsize
    Purpose:         See Section 5.3.2.4 of 3GPP TS 26.234
    Methods:         PLAY Response
    Reference:       Section 5.3.2.4 of 3GPP TS 26.234
    Values:          See Reference

Westerlund & Frojdh Informational [Page 18] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

    Header Name:     x-initpredecbufperiod
    Purpose:         See Section 5.3.2.4 of 3GPP TS 26.234
    Methods:         PLAY Response
    Reference:       Section 5.3.2.4 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     x-initpostdecbufperiod
    Purpose:         See Section 5.3.2.4 of 3GPP TS 26.234
    Methods:         PLAY Response
    Reference:       Section 5.3.2.4 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     3gpp-videopostdecbufsize
    Purpose:         See Section 5.3.2.4 of 3GPP TS 26.234
    Methods:         PLAY Response
    Reference:       Section 5.3.2.4 of 3GPP TS 26.234
    Values:          See Reference
    Header Name:     Supported
    Purpose:         See Section 5.5.2.2.2 of 3GPP TS 26.234
    Methods:         Any Request and Response
    Reference:       Section 5.5.2.2.2 of 3GPP TS 26.234
    Values:          See Reference
 IANA has registered the RTSP Option tags (option tags) listed below
 in the RTSP/1.0 Option Tags table of the "Real Time Streaming
 Protocol (RTSP)/1.0 Parameters" registry available from
 http://www.iana.org/.
    Option tag:      3gpp-pipelined
    Purpose:         See Section 5.5.3 of 3GPP TS 26.234
    Applies to:      Client and Server
    Reference:       Section 5.5.3 of 3GPP TS 26.234
    Values:          See Reference
    Option tag:      3gpp-switch
    Purpose:         See Section 5.5.4.2 of 3GPP TS 26.234
    Applies to:      Client and Server
    Reference:       Section 5.5.4.2 of 3GPP TS 26.234
    Values:          See Reference
    Option tag:      3gpp-switch-req-sdp
    Purpose:         See Section 5.5.4.4 of 3GPP TS 26.234
    Applies to:      Client and Server
    Reference:       Section 5.5.4.4 of 3GPP TS 26.234
    Values:          See Reference

Westerlund & Frojdh Informational [Page 19] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

    Option tag:      3gpp-switch-stream
    Purpose:         See Section 5.5.4.5 of 3GPP TS 26.234
    Applies to:      Client and Server
    Reference:       Section 5.5.4.5 of 3GPP TS 26.234
    Values:          See Reference

9. Security Considerations

 SDP attributes are subject to modification by an attacker unless they
 are integrity protected and authenticated.  The security
 considerations of the SDP specification [RFC4566] should be reviewed
 in this regard.  The registered SDP attributes are vulnerable to
 modification attacks or removal, which may result in problems of a
 serious nature, including failure to use service and reduced quality.
 The registered RTSP headers are also vulnerable to insertion,
 deletion, or modification attacks similar to SDP attributes.  Also in
 this case, attacks can result in failure of the service or reduced
 quality of streaming content.
 The three SDP protocol identifiers do not by themselves introduce any
 additional security threats that don't exist for other protocol
 identifiers in SDP.  The media stream and the used protocols
 identified and configured by the SDP protocol identifier may,
 however, contain security issues by themselves.

10. References

10.1. Normative References

 [MBMS]     3GPP TS 26.346 version 7.10.0 (2009-03), "Multimedia
            Broadcast/Multicast Service (MBMS); Protocols and codecs".
 [PSS-234]  3GPP TS 26.234 version 7.7.0 (2009-03), "Transparent end-
            to-end Packet-switched Streaming Service (PSS); Protocols
            and codecs".
 [PSS-3GP]  3GPP TS 26.244 version 7.3.0 (2007-12), "Transparent end-
            to-end packet switched streaming service (PSS); 3GPP file
            format (3GP)".
 [RFC0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
            August 1980.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.

Westerlund & Frojdh Informational [Page 20] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

 [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
            Video Conferences with Minimal Control", STD 65, RFC 3551,
            July 2003.
 [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
            Norrman, "The Secure Real-time Transport Protocol (SRTP)",
            RFC 3711, March 2004.

10.2. Informative References

 [AES]      NIST, "Advanced Encryption Standard (AES)", FIPS PUB 197,
            <http://www.nist.gov/itl/fipscurrent.cfm>.
 [PSS-233]  3GPP TS 26.233 version 7.0.0 (2007-06), "Transparent end-
            to-end packet switched streaming service (PSS) General
            Description".
 [RFC2326]  Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
            Streaming Protocol (RTSP)", RFC 2326, April 1998.
 [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
            with Session Description Protocol (SDP)", RFC 3264,
            June 2002.
 [RFC3890]  Westerlund, M., "A Transport Independent Bandwidth
            Modifier for the Session Description Protocol (SDP)",
            RFC 3890, September 2004.
 [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
            Description Protocol", RFC 4566, July 2006.
 [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
            Encodings", RFC 4648, October 2006.

Westerlund & Frojdh Informational [Page 21] RFC 6064 SDP and RTSP Extensions for 3GPP January 2011

Authors' Addresses

 Magnus Westerlund
 Ericsson
 Farogatan 6
 Stockholm  SE-164 80
 SWEDEN
 Phone: +46 10 7190000
 Fax:   +46 10 757 55 50
 EMail: magnus.westerlund@ericsson.com
 Per Frojdh
 Ericsson
 Farogatan 6
 Stockholm  SE-164 80
 SWEDEN
 Phone: +46 10 7190000
 Fax:   +46 10 757 55 50
 EMail: per.frojdh@ericsson.com

Westerlund & Frojdh Informational [Page 22]

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