draft-ietf-sipcore-6665-clarification-00.txt   rfc7621.txt 
Network Working Group A. B. Roach Internet Engineering Task Force (IETF) A.B. Roach
Internet-Draft Mozilla Request for Comments: 7621 Mozilla
Updates: 6665 (if approved) February 27, 2015 Updates: 6665 August 2015
Intended status: Standards Track Category: Standards Track
Expires: August 31, 2015 ISSN: 2070-1721
A clarification on the use of Globally Routable User Agent URIs (GRUUs) A Clarification on the Use of Globally Routable User Agent URIs (GRUUs)
in the Session Initiation Protocol (SIP) Event Notification Framework in the SIP Event Notification Framework
draft-ietf-sipcore-6665-clarification-00
Abstract Abstract
Experience since the publication of the most recent SIP Events Experience since the publication of the most recent SIP Events
framework has shown that there is room for interpretation around the framework (in July 2012) has shown that there is room for
use of Globally Routable User Agent URIs in that specification. This interpretation around the use of Globally Routable User Agent URIs in
document clarifies the intended behavior. that specification. This document clarifies the intended behavior.
This document updates RFC 6665. This document updates RFC 6665.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on August 31, 2015. 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/rfc7621.
Copyright Notice Copyright Notice
Copyright (c) 2015 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 15 skipping to change at page 2, line 12
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Clarification of GRUU Handling . . . . . . . . . . . . . . . 2 2. Clarification of GRUU Handling . . . . . . . . . . . . . . . 2
3. Security Considerations . . . . . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Normative References . . . . . . . . . . . . . . . . . . . . 3 5. Normative References . . . . . . . . . . . . . . . . . . . . 3
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 3 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction 1. Introduction
This document is intended to clarify a point of implementor confusion This document is intended to clarify a point of implementor confusion
arising from lack of clarity in [RFC2119]. arising from lack of clarity in [RFC6665].
2. Clarification of GRUU Handling 2. Clarification of GRUU Handling
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].
[RFC6665] section 4.5.1 contains the following normative requirement Section 4.5.1 of [RFC6665] contains the following normative
on implementations: requirement on implementations:
Notifiers MUST implement the Globally Routable User Agent URI Notifiers MUST implement the Globally Routable User Agent URI
(GRUU) extension defined in [RFC5627], and MUST use a GRUU as (GRUU) extension defined in [RFC5627], and MUST use a GRUU as
their local target. This allows subscribers to explicitly target their local target. This allows subscribers to explicitly target
desired devices. desired devices.
The second sentence of this paragraph attempted to set context for The second sentence of this paragraph attempted to set context for
the normative statement: the reason GRUUs are required in this the normative statement: the reason GRUUs are required in this
context is to allow you to send SUBSCRIBE or REFER requests to a context is to allow you to send SUBSCRIBE or REFER requests to a
specific user agent, with the target of the subscription request specific user agent, with the target of the subscription request
being something like an INVITE dialog on that device. Consequently, being something like an INVITE dialog on that device. Consequently,
the requirement to include a GRUU as a local target was intended to the requirement to include a GRUU as a local target was intended to
apply not just to the local target for SUBSCRIBE-created dialogs, but apply not just to the local target for SUBSCRIBE-created dialogs, but
for *all* dialogs, even those created by INVITE. This requirement to *all* dialogs, even those created by INVITE. This requirement has
has been interpreted in a variety of ways by implementors, so a been interpreted in a variety of ways by implementors, so a
clarification is in order. clarification is in order.
Discussion subsequent to the publication of [RFC6665] has highlighted Discussion subsequent to the publication of [RFC6665] has highlighted
obscure cases in which implementations might be notifiers in some obscure cases in which implementations might be notifiers in some
contexts, but may not wish to act as notifiers in others. Under contexts, but may not wish to act as notifiers in others. Under
these narrow circumstances, the restriction described above is not these narrow circumstances, the restriction described above is not
necessary for dialogs about which the notifier will never accept necessary for dialogs about which the notifier will never accept
subscriptions (although the use of GRUUs in such a context causes no subscriptions (although the use of GRUUs in such a context causes no
harm, either). harm, either).
This document updates [RFC6665] to clarify the actual requirements: This document updates [RFC6665] to clarify the actual requirements.
"Notifiers MUST implement the Globally Routable User Agent URI (GRUU) The replacement text is as follows:
extension defined in [RFC5627]. Notifiers MUST use a GRUU as their
local target for all dialog-forming methods and all target-refresh Notifiers MUST implement the Globally Routable User Agent URI
methods, except for those dialogs for which they will reject all (GRUU) extension defined in [RFC5627]. Notifiers MUST use a GRUU
subscription requests (implicit or explicit). For clarity: an as their local target for all dialog-forming methods and all
implementation that uses a non-GRUU local contact under the exception target-refresh methods, except for those dialogs for which they
described above MUST reject a request that might create a will reject all subscription requests (implicit or explicit). For
subscription to the associated dialog, regardless of whether such clarity: an implementation that uses a non-GRUU local contact
subscription would be created by a SUBSCRIBE or a REFER message. The under the exception described above MUST reject a request that
rejection code under such conditions SHOULD be 403 (Forbidden) unless might create a subscription to the associated dialog, regardless
some other code is more appropriate to the circumstances. The of whether such subscription would be created by a SUBSCRIBE or a
foregoing requirements to implement and use GRUUs specifically REFER message. The rejection code under such conditions SHOULD be
include dialogs created by the INVITE method." 403 (Forbidden) unless some other code is more appropriate to the
circumstances. The foregoing requirements to implement and use
GRUUs specifically include dialogs created by the INVITE method.
3. Security Considerations 3. Security Considerations
This mechanism does not introduce any security issues beyond those This mechanism does not introduce any security issues beyond those
discussed in [RFC6665]. discussed in [RFC6665].
4. IANA Considerations 4. IANA Considerations
This document requests no actions of IANA. This document requests no actions of IANA.
5. Normative References 5. 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,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[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, DOI 10.17487/RFC5627, October 2009,
<http://www.rfc-editor.org/info/rfc5627>.
[RFC6665] Roach, A.B., "SIP-Specific Event Notification", RFC 6665, [RFC6665] Roach, A.B., "SIP-Specific Event Notification", RFC 6665,
July 2012. DOI 10.17487/RFC6665, July 2012,
<http://www.rfc-editor.org/info/rfc6665>.
Author's Address Author's Address
Adam Roach Adam Roach
Mozilla Mozilla
Dallas, TX Dallas, TX
US United States
Phone: +1 650 903 0800 x863 Phone: +1 650 903 0800 x863
Email: adam@nostrum.com Email: adam@nostrum.com
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