Explicit Subscriptions for the REFER Method
RFC 7614

Document Type RFC - Proposed Standard (August 2015; No errata)
Last updated 2015-10-14
Replaces draft-sparks-sipcore-refer-explicit-subscription
Stream IETF
Formats plain text 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 7614 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Ben Campbell
Send notices to (None)
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                         R. Sparks
Request for Comments: 7614                                        Oracle
Category: Standards Track                                    August 2015
ISSN: 2070-1721

              Explicit Subscriptions for the REFER Method

Abstract

   The Session Initiation Protocol (SIP) REFER request, as defined by
   RFC 3515, triggers an implicit SIP-Specific Event Notification
   framework subscription.  Conflating the start of the subscription
   with handling the REFER request makes negotiating SUBSCRIBE
   extensions impossible and complicates avoiding SIP dialog sharing.
   This document defines extensions to REFER that remove the implicit
   subscription and, if desired, replace it with an explicit one.

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/rfc7614.

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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Sparks                       Standards Track                    [Page 1]
RFC 7614              REFER Explicit Subscriptions           August 2015

Table of Contents

   1. Introduction ....................................................3
   2. Conventions .....................................................3
   3. Overview ........................................................4
      3.1. Explicit Subscriptions .....................................4
      3.2. No Subscriptions ...........................................5
   4. The Explicit Subscription Extension .............................5
      4.1. Sending a REFER ............................................5
      4.2. Processing a REFER Response ................................5
      4.3. Processing a Received REFER ................................6
      4.4. Subscribing to the 'refer' Event ...........................7
      4.5. Processing a Received SUBSCRIBE ............................7
      4.6. Sending a NOTIFY ...........................................7
      4.7. Managing 'refer' Event State ...............................8
      4.8. The Refer-Events-At Header Field ...........................8
   5. The No Subscription Extension ...................................9
      5.1. Sending a REFER ............................................9
      5.2. Processing a REFER Response ................................9
      5.3. Processing a Received REFER ................................9
   6. The 'explicitsub' and 'nosub' Option Tags ......................10
   7. Updates to RFC 3515 ............................................10
   8. Security Considerations ........................................10
   9. IANA Considerations ............................................12
      9.1. Register the 'explicitsub' Option Tag .....................12
      9.2. Register the 'nosub' Option Tag ...........................12
      9.3. Register the Refer-Events-At Header Field .................12
   10. References ....................................................13
      10.1. Normative References .....................................13
      10.2. Informative References ...................................13
   Author's Address ..................................................14

Sparks                       Standards Track                    [Page 2]
RFC 7614              REFER Explicit Subscriptions           August 2015

1.  Introduction

   REFER, as defined by [RFC3515], triggers an implicit SIP-Specific
   Event Framework subscription.  Sending a REFER within a dialog
   established by an INVITE results in dialog reuse and the associated
   problems described in [RFC5057].  The SIP-Specific Event Notification
   framework definition [RFC6665] disallows such dialog reuse.  Call
   transfer, as defined in [RFC5589], thus requires sending a REFER
   request on a new dialog, associating it with an existing dialog using
Show full document text