draft-ietf-mmusic-qos-identification-02.txt   draft-ietf-mmusic-qos-identification-03.txt 
MMUSIC James Polk MMUSIC James Polk
Internet-Draft Subha Dhesikan Internet-Draft Subha Dhesikan
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: April 13, 2009 Gonzalo Camarillo Expires: May 22, 2009 Gonzalo Camarillo
Ericsson Ericsson
October 10, 2008 November 18, 2008
Quality of Service (QoS) Mechanism Selection in the Session Description Quality of Service (QoS) Mechanism Selection in the Session Description
Protocol (SDP) Protocol (SDP)
draft-ietf-mmusic-qos-identification-02.txt draft-ietf-mmusic-qos-identification-03.txt
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Abstract Abstract
The offer/answer model for SDP assumes that endpoints establish The offer/answer model for SDP assumes that endpoints establish
somehow the QoS required for the media streams they establish. somehow the QoS required for the media streams they establish.
Endpoints in closed environments typically agree out of band (e.g., Endpoints in closed environments typically agree out of band (e.g.,
using configuration information) which QoS mechanism to use. using configuration information) which QoS mechanism to use.
However, on the Internet, there is more than one QoS service However, on the Internet, there is more than one QoS service
available. Consequently, there is a need for a mechanism to available. Consequently, there is a need for a mechanism to
negotiate which QoS mechanism to use for a particular media stream. negotiate which QoS mechanism to use for a particular media stream.
This document defines such a mechanism. This document defines such a mechanism.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. SDP Attributes Definition . . . . . . . . . . . . . . . . . . 3 3. SDP Attributes Definition . . . . . . . . . . . . . . . . . . 3
4. Offer/answer Behavior . . . . . . . . . . . . . . . . . . . . 4 4. Offer/answer Behavior . . . . . . . . . . . . . . . . . . . . 4
4.1. Offerer Behavior . . . . . . . . . . . . . . . . . . . . . 4 4.1. Offerer Behavior . . . . . . . . . . . . . . . . . . . . . 4
4.2. Answerer Behavior . . . . . . . . . . . . . . . . . . . . 4 4.2. Answerer Behavior . . . . . . . . . . . . . . . . . . . . 5
4.3. Resource Reservation . . . . . . . . . . . . . . . . . . . 5 4.3. Resource Reservation . . . . . . . . . . . . . . . . . . . 5
4.4. Subsequent Offer/answer Exchanges . . . . . . . . . . . . 5 4.4. Subsequent Offer/answer Exchanges . . . . . . . . . . . . 5
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. Registration of the SDP 'qos-mech-send' Attribute . . . . 6 6.1. Registration of the SDP 'qos-mech-send' Attribute . . . . 6
6.2. Registration of the SDP 'qos-mech-recv' Attribute . . . . 6 6.2. Registration of the SDP 'qos-mech-recv' Attribute . . . . 7
6.3. Registry for QoS Mechanism Tokens . . . . . . . . . . . . 7 6.3. Registry for QoS Mechanism Tokens . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8 9.1. Normative References . . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . . 8 9.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . . . 10
1. Introduction 1. Introduction
The offer/answer model [RFC3264] for SDP [RFC4566] does not provide The offer/answer model [RFC3264] for SDP [RFC4566] does not provide
any mechanism for endpoints to negotiate the QoS mechanism to be used any mechanism for endpoints to negotiate the QoS mechanism to be used
for a particular media stream. Even when QoS preconditions [RFC3312] for a particular media stream. Even when QoS preconditions [RFC3312]
are used, the choice of the QoS mechanism is left unspecified, up to are used, the choice of the QoS mechanism is left unspecified, up to
the endpoints. the endpoints.
Endpoints that support more than one QoS mechanism need a way to Endpoints that support more than one QoS mechanism need a way to
negotiate which one to use for a particular media stream. Examples negotiate which one to use for a particular media stream. Examples
of QoS mechanisms are RSVP (Resource Reservation Protocol) [RFC2205] of QoS mechanisms are RSVP (Resource Reservation Protocol) [RFC2205]
and NSIS (Next Steps in Signaling) [RFC4080]. and NSIS (Next Steps in Signaling) [I-D.ietf-nsis-qos-nslp].
This document defines a mechanism that allows endpoints to negotiate This document defines a mechanism that allows endpoints to negotiate
the QoS mechanism to be used for a particular media stream. the QoS mechanism to be used for a particular media stream. However,
Section 3 defines the 'qos-mech-send' and 'qos-mech-recv' SDP the fact that endpoints agree on a particular QoS mechanism does not
attributes. Section 4 specifies the use of these new SDP attributes imply that that particular mechanism is supported by the network.
with the offer/answer model. Section 5 provides an example of an Discovering which QoS mechanisms are supported at the network layer
offer/answer exchanges that uses these attributes. is out of the scope of this document. In any case, the information
the endpoints exchange to negotiate QoS mechanisms, as defined in
this document, can be useful for a network operator to resolve a
subset of the QoS interoperability problem, namely to ensure that a
mechanism commonly acceptable to the endpoints is chosen and make it
possible to debug possible misconfiguration situations.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. SDP Attributes Definition 3. SDP Attributes Definition
This document defines the 'qos-mech-send' and 'qos-mech-recv' session This document defines the 'qos-mech-send' and 'qos-mech-recv' session
and media-level SDP [RFC4566] attributes. The following is their and media-level SDP [RFC4566] attributes. The following is their
augmented Backus-Naur Form (BNF) [RFC5234] syntax, which is based on augmented Backus-Naur Form (BNF) [RFC5234] syntax, which is based on
the SDP [RFC4566] grammar: the SDP [RFC4566] grammar:
attribute = qos-mech-send-attr attribute =/ qos-mech-send-attr
attribute = qos-mech-recv-attr attribute =/ qos-mech-recv-attr
qos-mech-send-attr = "qos-mech-send" ":" *(SP qos-mech) qos-mech-send-attr = "qos-mech-send" ":"
qos-mech-recv-attr = "qos-mech-recv" ":" *(SP qos-mech) [[SP] qos-mech *(SP qos-mech)]
qos-mech-recv-attr = "qos-mech-recv" ":"
[[SP] qos-mech *(SP qos-mech)]
qos-mech = rsvp / nsis / extension-mech qos-mech = "rsvp" / "nsis" / extension-mech
extension-mech = token extension-mech = token
The 'qos-mech' token identifies a QoS mechanism that is supported by The 'qos-mech' token identifies a QoS mechanism that is supported by
the entity generating the session description. A token that appears the entity generating the session description. A token that appears
in a 'qos-mech-send' attribute identifies a QoS mechanism that can be in a 'qos-mech-send' attribute identifies a QoS mechanism that can be
used to reserve resources for traffic sent by the entity generating used to reserve resources for traffic sent by the entity generating
the session description. A token that appears in a 'qos-mech-recv' the session description. A token that appears in a 'qos-mech-recv'
attribute identifies a QoS mechanism that can be used to reserve attribute identifies a QoS mechanism that can be used to reserve
resources for traffic received by the entity generating the session resources for traffic received by the entity generating the session
description. description.
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Consequently, it is strongly RECOMMENDED that integrity and Consequently, it is strongly RECOMMENDED that integrity and
authenticity protection be applied to SDP session descriptions authenticity protection be applied to SDP session descriptions
carrying these attributes. For session descriptions carried in SIP carrying these attributes. For session descriptions carried in SIP
[RFC3261], S/MIME [RFC3851] is the natural choice to provide such [RFC3261], S/MIME [RFC3851] is the natural choice to provide such
end-to-end integrity protection, as described in [RFC3261]. Other end-to-end integrity protection, as described in [RFC3261]. Other
applications MAY use a different form of integrity protection. applications MAY use a different form of integrity protection.
8. Acknowledgements 8. Acknowledgements
Dave Oran helped form this effort. Flemming Andreasen provided Dave Oran helped form this effort. Flemming Andreasen and Magnus
useful comments on this specification. Westerlund provided useful comments on this specification.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
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[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
9.2. Informative References 9.2. Informative References
[I-D.ietf-nsis-qos-nslp]
Manner, J., Karagiannis, G., and A. McDonald, "NSLP for
Quality-of-Service Signaling", draft-ietf-nsis-qos-nslp-16
(work in progress), February 2008.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997. Functional Specification", RFC 2205, September 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002. June 2002.
[RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg, [RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg,
"Integration of Resource Management and Session Initiation "Integration of Resource Management and Session Initiation
Protocol (SIP)", RFC 3312, October 2002. Protocol (SIP)", RFC 3312, October 2002.
[RFC4080] Hancock, R., Karagiannis, G., Loughney, J., and S. Van den
Bosch, "Next Steps in Signaling (NSIS): Framework",
RFC 4080, June 2005.
Authors' Addresses Authors' Addresses
James Polk James Polk
Cisco Systems Cisco Systems
3913 Treemont Circle 3913 Treemont Circle
Colleyville, Texas 76034 Colleyville, Texas 76034
USA USA
Phone: +1-817-271-3552 Phone: +1-817-271-3552
Email: jmpolk@cisco.com Email: jmpolk@cisco.com
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