Session Initiation Protocol (SIP) Session Timer Glare Handling
draft-ietf-sipcore-sessiontimer-race-00
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SIPCORE Working Group C. Holmberg
Internet-Draft Ericsson
Updates: 4028 (if approved) October 4, 2017
Intended status: Standards Track
Expires: April 7, 2018
Session Initiation Protocol (SIP) Session Timer Glare Handling
draft-ietf-sipcore-sessiontimer-race-00
Abstract
This document updates RFC 4028, by clarifying the procedures for
negotiating usage of the Session Initiation Protocol (SIP) session
timer mechansim, in order to avoid a race condition where both
endpoints trigger simultaneous negotiations.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
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 https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 7, 2018.
Copyright Notice
Copyright (c) 2017 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
(https://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.
Holmberg Expires April 7, 2018 [Page 1]
Internet-Draft Session timer glare October 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Problem Statement . . . . . . . . . . . . . . . . . . . . 2
1.2. Solution . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Update to RFC 4028 . . . . . . . . . . . . . . . . . . . . . 3
3.1. Update to Section 7.2 . . . . . . . . . . . . . . . . . . 3
3.2. Update to Section 7.4 . . . . . . . . . . . . . . . . . . 4
3.3. Update to Section 8.1 . . . . . . . . . . . . . . . . . . 5
3.4. Update to Section 9 . . . . . . . . . . . . . . . . . . . 6
4. Security considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Change log . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Normative references . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC4028] defines a mechanism, where periodic SIP requests are sent
in order to allow SIP user agents and proxies to determine whether a
SIP session is still active.
The usage of the mechanism is negotiated using two new SIP header
fields (Session-Expires and Min-SE), a new option tag ('timer') and a
new SIP response code (422).
1.1. Problem Statement
1. Section 7.4 of [RFC4028] says that, in a session refresh request
sent within a dialog with an active session timer, the Session-
Expires header field should be included in the request. However, the
text is unclear regarding including the Session-Expires header field
in a session refresh request when a negotiation of session timer
usage is still ongoing, e.g., if one user agent is sending a request
that contains a Session-Expires header field and, before it receives
the associated 2xx response, receives a request from the peer user
agent that also contains a Session-Expires header field. Such
scenario might cause a glare situation, with conflicting negotiation
parameters.
2. The absence of the Session-Expires header field in a 2xx response
to an (re-)INVITE request [RFC3261] or UPDATE request [RFC3311] means
that the mechanism isn't used. This can be used to reject the usage
of the mechanism when sending a response. However, the text is
unclear that this only applies to cases where the associated SIP
request contained a Session-Expires header field.
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