draft-ietf-sipcore-refer-clarifications-00.txt   draft-ietf-sipcore-refer-clarifications-01.txt 
Network Working Group R. Sparks Network Working Group R. Sparks
Internet-Draft Oracle Internet-Draft Oracle
Updates: 3515 (if approved) A. Roach Updates: 3515 (if approved) A. Roach
Intended status: Standards Track Mozilla Intended status: Standards Track Mozilla
Expires: May 25, 2015 November 21, 2014 Expires: July 25, 2015 January 21, 2015
Clarifications for the use of REFER with RFC6665 Clarifications for the use of REFER with RFC6665
draft-ietf-sipcore-refer-clarifications-00 draft-ietf-sipcore-refer-clarifications-01
Abstract Abstract
The SIP REFER method relies on the SIP-Specific Event Notification The SIP REFER method relies on the SIP-Specific Event Notification
Framework. That framework was revised by RFC6665. This document Framework. That framework was revised by RFC6665. This document
highlights the implications of the requirement changes in RFC6665, highlights the implications of the requirement changes in RFC6665,
and updates the definition of the REFER method, RFC3515, to clarify and updates the definition of the REFER method, RFC3515, to clarify
and disambiguate the impact of those changes. and disambiguate the impact of those changes.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 25, 2015. This Internet-Draft will expire on July 25, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Conventions and Definitions . . . . . . . . . . . . . . . . . 2 1. Conventions and Definitions . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Use of GRUU is mandatory . . . . . . . . . . . . . . . . . . 2 3. Use of GRUU is mandatory . . . . . . . . . . . . . . . . . . 3
4. Dialog reuse is prohibited . . . . . . . . . . . . . . . . . 3 4. Dialog reuse is prohibited . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . 4 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Conventions and Definitions 1. Conventions and Definitions
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].
2. Introduction 2. Introduction
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and updates [RFC3515] to clarify and disambiguate the impact of those and updates [RFC3515] to clarify and disambiguate the impact of those
changes. changes.
Accepting a REFER request (without invoking extensions) results in an Accepting a REFER request (without invoking extensions) results in an
implicit SIP-Events subscription. If that REFER was part of an implicit SIP-Events subscription. If that REFER was part of an
existing dialog, the implicit subscription creates a new, problematic existing dialog, the implicit subscription creates a new, problematic
dialog-usage within that dialog [RFC5057]. The "norefersub" dialog-usage within that dialog [RFC5057]. The "norefersub"
extension defined in [RFC4488] asks to suppress this implicit extension defined in [RFC4488] asks to suppress this implicit
subscription, but cannot prevent its creation. subscription, but cannot prevent its creation.
There are implementations in some known specialized environments
(such as 3gpp) that use out-of-signalling agreements to ensure that
in-dialog REFER requests using the RFC4488 extension do not create a
new subscription inside that dialog. In the 3gpp environment, the
behavior is based on capabilities advertised using media feature
tags. That mechanism does not, however, prevent additional dialog
usages when interoperating with implementations that do not support
the mechanism. The extensions in
[I-D.ietf-sipcore-refer-explicit-subscription] provide a standardized
mechanism that allows avoiding any additional dialog usage.
3. Use of GRUU is mandatory 3. Use of GRUU is mandatory
Section 4.5.1 of [RFC6665] makes GRUU [RFC5627] mandatory for Section 4.5.1 of [RFC6665] makes GRUU [RFC5627] mandatory for
notifiers to implement and use as the local target in the notifiers to implement and use as the local target in the
subscription created by the REFER request. subscription created by the REFER request.
A user agent accepting a REFER that creates a subscription MUST A user agent accepting a REFER that creates a subscription MUST
populate its Contact header field with a GRUU. populate its Contact header field with a GRUU.
A UA that will accept a REFER request needs to include a GRUU in the A UA that will accept a REFER request needs to include a GRUU in the
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5. Security Considerations 5. Security Considerations
This document introduces no new security considerations directly. This document introduces no new security considerations directly.
The updated considerations in [RFC6665] apply to the implicit The updated considerations in [RFC6665] apply to the implicit
subscription created by an accepted REFER request. subscription created by an accepted REFER request.
6. IANA Considerations 6. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
7. Changelog 7. Acknowledgements
Christer Holmberg provided the formulation for the final paragraph of
the introduction. Christer Holmberg and Ivo Sedlacek provided
detailed comments during working group discussion of the document.
8. Changelog
RFC Editor - please remove this section when formatting this document RFC Editor - please remove this section when formatting this document
as an RFC as an RFC
-00 to -01
Added the 3rd paragraph to the introduction per extensive list
discussion
draft-sparks-sipcore-refer-clarifications-05 to draft-ietf- draft-sparks-sipcore-refer-clarifications-05 to draft-ietf-
sipcore-refer-clarifications-00 sipcore-refer-clarifications-00
Attempted to improve the accuracy of the Abstract and Attempted to improve the accuracy of the Abstract and
Introduction without diluting the essential point of the Introduction without diluting the essential point of the
document. document.
Added an informative reference to RFC5057. Added an informative reference to RFC5057.
Adjusted text to more reflect what RFC6665 (as clarified by Adjusted text to more reflect what RFC6665 (as clarified by
draft-roach-sipcore-6665-clarification) actually requires, and draft-roach-sipcore-6665-clarification) actually requires, and
added a normative reference to that clarification draft. added a normative reference to that clarification draft.
Specifically, the requirement for the _sender_ of a REFER to Specifically, the requirement for the _sender_ of a REFER to
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Adjusted text to more reflect what RFC6665 (as clarified by Adjusted text to more reflect what RFC6665 (as clarified by
draft-roach-sipcore-6665-clarification) actually requires, and draft-roach-sipcore-6665-clarification) actually requires, and
added a normative reference to that clarification draft. added a normative reference to that clarification draft.
Specifically, the requirement for the _sender_ of a REFER to Specifically, the requirement for the _sender_ of a REFER to
use a GRUU as its local targetwas removed. use a GRUU as its local targetwas removed.
Clarified why the explicit-subscription extensions relieve an Clarified why the explicit-subscription extensions relieve an
in-dialog REFERer from the 6665 requirements for using GRUU as in-dialog REFERer from the 6665 requirements for using GRUU as
its contact in the INVITE dialog. its contact in the INVITE dialog.
8. References 9. References
8.1. Normative References 9.1. Normative References
[I-D.roach-sipcore-6665-clarification] [I-D.roach-sipcore-6665-clarification]
Roach, A., "A clarification on the use of Globally Roach, A., "A clarification on the use of Globally
Routable User Agent URIs (GRUUs) in the Session Initiation Routable User Agent URIs (GRUUs) in the Session Initiation
Protocol (SIP) Event Notification Framework", draft-roach- Protocol (SIP) Event Notification Framework", draft-roach-
sipcore-6665-clarification-00 (work in progress), October sipcore-6665-clarification-00 (work in progress), October
2014. 2014.
[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.
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Identification in the Session Initiation Protocol (SIP)", Identification in the Session Initiation Protocol (SIP)",
RFC 4538, June 2006. RFC 4538, June 2006.
[RFC5627] Rosenberg, J., "Obtaining and Using Globally Routable User [RFC5627] Rosenberg, J., "Obtaining and Using Globally Routable User
Agent URIs (GRUUs) in the Session Initiation Protocol Agent URIs (GRUUs) in the Session Initiation Protocol
(SIP)", RFC 5627, October 2009. (SIP)", RFC 5627, October 2009.
[RFC6665] Roach, A., "SIP-Specific Event Notification", RFC 6665, [RFC6665] Roach, A., "SIP-Specific Event Notification", RFC 6665,
July 2012. July 2012.
8.2. Informative References 9.2. Informative References
[I-D.ietf-sipcore-refer-explicit-subscription] [I-D.ietf-sipcore-refer-explicit-subscription]
Sparks, R., "Explicit Subscriptions for the REFER Method", Sparks, R., "Explicit Subscriptions for the REFER Method",
draft-ietf-sipcore-refer-explicit-subscription-00 (work in draft-ietf-sipcore-refer-explicit-subscription-00 (work in
progress), November 2014. progress), November 2014.
[RFC4488] Levin, O., "Suppression of Session Initiation Protocol [RFC4488] Levin, O., "Suppression of Session Initiation Protocol
(SIP) REFER Method Implicit Subscription", RFC 4488, May (SIP) REFER Method Implicit Subscription", RFC 4488, May
2006. 2006.
 End of changes. 13 change blocks. 
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