Clarifications for the Use of REFER with RFC 6665
RFC 7647
| Document | Type |
RFC - Proposed Standard
(September 2015; No errata)
Updates RFC 3515
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-sparks-sipcore-refer-clarifications | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Paul Kyzivat | ||
| Shepherd write-up | Show (last changed 2015-04-29) | ||
| IESG | IESG state | RFC 7647 (Proposed Standard) | |
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Ben Campbell | ||
| Send notices to | (None) | ||
| IANA | IANA review state | IANA OK - No Actions Needed | |
| IANA action state | No IANA Actions | ||
Internet Engineering Task Force (IETF) R. Sparks
Request for Comments: 7647 Oracle
Updates: 3515 A.B. Roach
Category: Standards Track Mozilla
ISSN: 2070-1721 September 2015
Clarifications for the Use of REFER with RFC 6665
Abstract
The SIP REFER method relies on the SIP-Specific Event Notification
framework. That framework was revised by RFC 6665. This document
highlights the implications of the requirement changes in RFC 6665,
and updates the definition of the REFER method described in RFC 3515
to clarify and disambiguate the impact of those changes.
Status of This Memo
This is an Internet Standards Track document.
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). Further information on
Internet Standards is available in 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/rfc7647.
Copyright Notice
Copyright (c) 2015 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Sparks & Roach Standards Track [Page 1]
RFC 7647 Refer Clarifications September 2015
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 2
3. Use of GRUU Is Mandatory . . . . . . . . . . . . . . . . . . 3
4. Dialog Reuse Is Prohibited . . . . . . . . . . . . . . . . . 3
5. The 202 Response Code Is Deprecated . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The SIP REFER method relies on the SIP-Specific Event Notification
framework. That framework was revised by [RFC6665]. This document
highlights the implications of the requirement changes in RFC 6665,
and updates [RFC3515] to clarify and disambiguate the impact of those
changes.
Accepting a REFER request (without invoking extensions) results in an
implicit SIP-Events subscription. If that REFER was part of an
existing dialog, the implicit subscription creates a new, problematic
dialog usage within that dialog [RFC5057]. The "norefersub"
extension defined in [RFC4488] asks to suppress this implicit
subscription, but cannot prevent its creation.
There are implementations in some known specialized environments
(such as 3GPP) that use out-of-signaling agreements to ensure that
in-dialog REFER requests using the RFC 4488 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 [RFC7614] provide a standardized
mechanism that allows avoiding any additional dialog usage.
2. Conventions Used in This Document
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].
Sparks & Roach Standards Track [Page 2]
RFC 7647 Refer Clarifications September 2015
3. Use of GRUU Is Mandatory
Section 4.5.1 of [RFC6665] makes GRUU [RFC5627] mandatory for
notifiers to implement and use as the local target in the
subscription created by the REFER request.
A user agent (UA) accepting a REFER that creates a subscription MUST
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