Internet DRAFT - draft-lavers-dispatch-immersive-capability
draft-lavers-dispatch-immersive-capability
DISPATCH G. Lavers
Internet-Draft P. Jones
Intended status: Standards Track G. Salgueiro
Expires: September 6, 2012 Cisco Systems
March 5, 2012
Indicating the Immersive User Agent Capability
in the Session Initiation Protocol (SIP)
draft-lavers-dispatch-immersive-capability-00
Abstract
This document defines and registers with IANA the new 'immersive'
media feature tag for use with the Session Initiation Protocol (SIP).
This media feature tag can be used to route calls to a device that
can provide an immersive communication experience, such as a
Telepresence system.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 6, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Registration . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Session Establishment . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
Videoconferencing systems that utilize SIP [1] can be broadly
classified as "traditional" videoconferencing systems or
"Telepresence" systems. Most SIP implementations today are
classified as traditional videoconferencing systems, but there are a
growing number of telepresence systems that would benefit in
differentiating the two through a media feature tag.
The traditional videoconferencing system, which might include any
room-based system, desktop videophone, or application running on a
computer, tablet, mobile phone, or similar device, typically uses
lower-resolution video images and does not make an attempt to provide
a real-life, immersive conferencing experience. Some traditional
systems do employ high definition (HD) video, but still lack the
quality of providing an in-person communication experience.
Telepresence systems, on the other hand, are visual conferencing
environments that duplicate, as closely as possible, an in-person
experience. The objective of such systems is to make the
participants in the conference feel as if they are physically
together, providing an immersive, realistic experience.
This document defines the "immersive" media feature tag for use in
the SIP tree, as per Section 12.1 of RFC 3840 [RFC3840]. This
feature tag can be utilized by SIP B2BUAs, SIP proxies, or other
elements in the SIP network to help ensure the best communication
experience for those wishing to establish a telepresence session or
other communication session that might be classified as providing an
immersive, realistic user experience.
2. Terminology
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 [RFC2119].
"SHOULD", "SHOULD NOT", "RECOMMENDED", and "NOT RECOMMENDED" are
appropriate when valid exceptions to a general requirement are known
to exist or appear to exist, and it is infeasible or impractical to
enumerate all of them. However, they should not be interpreted as
permitting implementors to fail to implement the general requirement
when such failure would result in interoperability failure.
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3. Motivation
The primary motivation for defining an immersive media feature tag is
for the transmission of a feature capability that implies a specific
"user experience" that is differentiated from classic video. This
feature tag can be considered by the various network elements to
realize several possible use cases. To name a few:
o Admission control decisions: A system could use the media feature
tags such as immersive, video, audio, etc. to allow network
elements to reserve bandwidth or take measures to ensure the best
possible experience.
o Selective routing decisions: A proxy or B2BUA could leverage the
immersive feature tag to help make routing decisions, including
the selection of a specific end system that supports the feature
capability or to route a call over specific network segments.
4. Examples
The following examples omit the message body and various header
fields for brevity.
4.1. Registration
Bob registers with the immersive media feature tag. The message flow
is shown in Figure 1:
SIP Registrar Bob's
Telepresence Endpoint
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| REGISTER F1 |
|<------------------------------|
| |
| 200 OK F2 |
|------------------------------>|
| |
Figure 1: Immersive Media Feature Tag SIP Registration Example
F1 REGISTER Bob -> Registrar
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REGISTER sip:example.com SIP/2.0
Via: SIP/2.0/TCP bob-TP@example.com;branch=z9hG4bK309475a2
From: <sip:bob-tp@example.com>;tag=a6c85cf
To: <sip:bob-tp@pexample.com>
Call-ID: a84b4c76e66710
Max-Forwards: 70
CSeq: 116 REGISTER
Contact: <sip:bob-tp@example.com;transport=tcp>;immersive
Expires: 3600
The registrar responds with a 200 OK:
F2 200 OK Registrar -> Bob
SIP/2.0 200 OK
From: <sip:bob-tp@example.com>;tag=a6c85cf
To: <sip:bob-tp@example.com>;tag=1263390604
Contact: <sip:bob-tp@example.com;transport=tcp>;immersive
Expires: 120
Call-ID: a84b4c76e66710
Via: SIP/2.0/TCP bob-TP@example.com;branch=z9hG4bK309475a2
CSeq: 116 REGISTER
Expires: 3600
4.2. Session Establishment
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Bob initiates a delayed offer call to Alice indicating that he
supports the immersive media feature tag while Alice responds with
her support of the immersive media feature tag. The message flow is
shown in Figure 2:
Bob Alice
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| INVITE F1 |
|------------------------------>|
| |
| 180 Ringing F2 |
|<------------------------------|
| |
| 200 OK F3 |
|<------------------------------|
| |
| ACK F4 |
|------------------------------>|
| |
| Media F5 |
|<=============================>|
| |
Figure 2: Immersive Media Feature Tag SIP Session Establishment
Example
F1 INVITE Bob -> Alice
INVITE sip:alice@example.com SIP/2.0
Via: SIP/2.0/TCP bob-TP@example.com;branch=z9hG4bKnashds8
From: "bob" <sip:bob-tp@example.com>;tag=a6c85cf
To: "alice" <sip:alice@example.com>
Date: Tue, 01 Nov 2011 18:28:52 GMT
Call-ID: a84b4c76e66710
CSeq: 101 INVITE
Contact: <sip:bob-tp@example.com;transport=tcp>;immersive
Max-Forwards: 69
Content-Length: 0
F2 180 Ringing Alice -> Bob
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SIP/2.0 180 Ringing
Via: SIP/2.0/TCP alice@example.com;branch=z9hG4bKnashds8
From: "alice" <sip:alice@example.com>;tag=1928301774
To: "bob" <sip:bob-tp@example.com>;tag=a6c85cf
Date: Tue, 01 Nov 2011 18:28:52 GMT
Call-ID: a84b4c76e66710
CSeq: 101 INVITE
Contact: <sip:alice@example.com;transport=tcp>;immersive
Content-Length: 0
F3 200 OK Alice -> Bob
SIP/2.0 200 OK
Via: SIP/2.0/TCP alice@example.com;branch=z9hG4bKnashds8
From: "alice" <sip:alice@example.com>;tag=1928301774
To: "bob" <sip:bob-tp@example.com>;tag=a6c85cf
Date: Tue, 01 Nov 2011 18:28:52 GMT
Call-ID: a84b4c76e66710
CSeq: 101 INVITE
Contact: <sip:alice@example.com;transport=tcp>;immersive
Content-Type: application/sdp
Content-Length: 1963
F4 ACK Bob -> Alice
ACK sip:aliceexample.com;transport=tcp SIP/2.0
Via: SIP/2.0/TCP 10.0.0.2:5060;branch=z9hG4bKnashds9
From: "bob" <sip:bob-tp@example.com>;tag=a6c85cf
To: "alice" <sip:alice@example.com>;tag=1928301774
Date: Tue, 01 Nov 2011 18:28:52 GMT
Call-ID: a84b4c76e66710
Max-Forwards: 70
CSeq: 101 ACK
Contact: <sip:bob-tp@example.com;transport=tcp>;immersive
Content-Type: application/sdp
Content-Length: 1452
F5 Media transmission Bob <-> Alice
Media streams are established between Bob and Alice.
5. Security Considerations
The security considerations related to the use of media feature tags
from Section 11.1 of RFC 3840 [RFC3840] apply.
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6. IANA Considerations
This specification adds a new media feature tag to the SIP Media
Feature Tag Registration Tree per the procedures defined in RFC 2506
[RFC2506] and RFC 3840 [RFC3840].
Media feature tag name: sip.immersive
ASN.1 Identifier: 1.3.6.1.8.4.{PH}
Summary of the media feature indicated by this tag: This feature tag
indicates that the device provides an immersive audio and/or video
communication experience.
Values appropriate for use with this feature tag: Boolean.
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms: This
feature tag is most useful in a communications application for
describing the capabilities of a device, such as a Telepresence
system.
Examples of typical use: Routing a call to a multimedia
communication system that can provide an immersive communication
experience.
Related standards or documents: RFCXXXX
Security Considerations: Security considerations for this media
feature tag are discussed in Section 5 of this document.
[[NOTE TO RFC EDITOR: Please change {PH} above to the correct
identifier for this entry in the IANA registry for
iso.org.dod.internet.features.sip-tree (1.3.6.1.8.4)]]
[[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to
this specification, and remove this paragraph on publication.]]
7. Acknowledgements
Thanks go to the Medianet Session Control group at Cisco for their
insightful discussion, advice and feedback that led to the creation
of this document.
8. References
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8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
"Indicating User Agent Capabilities in the Session
Initiation Protocol (SIP)", RFC 3840, August 2004.
8.2. Informative References
[RFC2506] Holtman, K., Mutz, A., and T. Hardie, "Media Feature Tag
Registration Procedure", BCP 31, RFC 2506, March 1999.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
Authors' Addresses
Glen Lavers
Cisco Systems
Mail Stop LKO2/3/
5400 Meadows Road
LAKE OSWEGO, OR 97035
US
Email: glavers@cisco.com
Paul E. Jones
Cisco Systems
7025 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: paulej@packetizer.com
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Gonzalo Salgueiro
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: gsalguei@cisco.com
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