Sipping P. Kyzivat
Internet-Draft Cisco Systems, Inc.
Expires: April 3, 2006 September 30, 2005
Reg Event Package Extension for GRUUs
draft-ietf-sipping-gruu-reg-event-00
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This draft defines an extension to RFC 3680 [1] for representing the
GRUU associated with a Contact.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Description . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Notifier Processing of SUBSCRIBE Requests . . . . . . . . . . 3
4. Notifier Generation of NOTIFY Requests . . . . . . . . . . . . 4
5. Subscriber Processing of NOTIFY Requests . . . . . . . . . . . 4
6. Sample reginfo Document . . . . . . . . . . . . . . . . . . . 4
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Example: Welcome Notice . . . . . . . . . . . . . . . . . 5
7.2. Example: Implicit Registration . . . . . . . . . . . . . . 5
8. XML Schema Definition . . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. Security Considerations . . . . . . . . . . . . . . . . . . . 9
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
12.1. Normative References . . . . . . . . . . . . . . . . . . . 9
12.2. Informative References . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 12
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1. Introduction
The addition of GRUU (Globally Routable Unique URI) support to the
REGISTER message, defined in [2], introduces another element of state
to the registrar. Subscribers to the registration event package [1]
will sometimes have need for the new state.
For example, the Welcome Notices example in [1] will only operate
correctly if the contact address in the reg event notification is
reachable by the sender of the welcome notice. When the registering
device is using the gruu extension, it is likely that the registered
contact address will not be globally addressable, and the gruu should
be used as the target address for the MESSAGE.
Another case where this feature may be helpful is within the 3GPP IP
Multimedia Subsystem (IMS). IMS employs a technique where a REGISTER
of a contact address to one Address of Record (AOR) causes the
implicit registration of the same contact to other associated AORs.
If a GRUU is requested and obtained as part of the registration
request, then additional GRUUs will also be needed for the implicit
registrations. While assigning the additional GRUUs is
straightforward, informing the registering UA of them is not. In
IMS, UAs typically subscribe to the 'reg' event, and subscriptions to
the 'reg' event for an AOR result in notifications containing
registration state for all the associated AORs. The proposed
extension provides a way to easily deliver the GRUUs for the
associated AORs.
The reg event package has provision for including extension elements
within the <contact> element. This document defines a new element
that may be used in that context to deliver the GRUU corresponding to
the contact.
2. Description
A new element (<gruu>) is defined which contains a GRUU.
This optional element is included within the body of a NOTIFY for the
"reg" event package when a GRUU is associated with the contact. The
contact URI and the GRUU are then both available to the watcher.
3. Notifier Processing of SUBSCRIBE Requests
Unchanged from RFC 3680 [1].
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4. Notifier Generation of NOTIFY Requests
A notifier for the "reg" event package [1] SHOULD include the <gruu>
element when a contact has an Instance ID and a GRUU is associated
with the combination of the AOR and the Instance ID. When present,
the <gruu> element MUST be be positioned as an instance of the <any>
element within the <contact> element.
5. Subscriber Processing of NOTIFY Requests
When a subscriber receives a "reg" event notification [1] with a
<contact> containing a <gruu>, it SHOULD use the gruu in preference
to the corresponding <uri> when sending SIP requests to the contact.
Subscribers that are unaware of this extension will, as required by
[1], ignore the <gruu> element.
6. Sample reginfo Document
The following is an example registration information document
including the new element:
<?xml version="1.0"?>
<reginfo xmlns="urn:ietf:params:xml:ns:reginfo"
xmlns:gr="urn:ietf:params:xml:ns:gruuinfo"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
version="0" state="full">
<registration aor="sip:user@example.com" id="as9"
state="active">
<contact id="76" state="active" event="registered"
duration-registered="7322"
q="0.8">
<uri>sip:user@192.0.2.1</uri>
<unknown-param name="+sip.instance">
"<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
</unknown-param>
<gr:gruu>
sip:user@example.com;opaque=hha9s8d-999a
</gruu>
</contact>
</registration>
</reginfo>
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7. Examples
Note: In the following examples the SIP messages have been
simplified, removing headers that are not pertinent to the example.
The conventions of [7] are used to describe representation of long
message lines.
7.1. Example: Welcome Notice
Consider the Welcome Notices example in [1]. When the application
server receives a notification of a new registration containing the
reginfo shown in Section 6 it should address messages using the
contained GRUU as follows:
MESSAGE sip:user@example.com;opaque=hha9s8d-999a SIP/2.0
To: <sip:user@example.com>
From: "SIPland Notifier" <sip:notifier@example.com>
Content-Type: text/plain
Content-Length: ...
Welcome to SIPland!
Blah, blah, blah.
7.2. Example: Implicit Registration
In an 3GPP IMS setting, a UA may send a single register message,
requesting assignment of a gruu, as follows:
REGISTER sip:example.net SIP/2.0
From: <sip:user_aor_1@example.net>;tag=5ab4
To: <sip:user_aor_1@example.net>
Contact: <sip:ua.example.com>
;expires=3600
;+sip.instance="<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
Supported: path, gruu
Content-Length: 0
The response reports success of the registration and returns the GRUU
assigned for the combination of AOR, Instance ID, and Contact. It
also indicates (via the P-Associated-URI header [5]) that there are
two other associated AORs that may have been implicitly registered
using the same contact. But each of those implicitly registered AORs
will have had a unique GRUU assigned, and there is no way defined to
report that assignment in the response.
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SIP/2.0 200 OK
From: <sip:user_aor_1@example.net>;tag=5ab4
To: <sip:user_aor_1@example.net>;tag=373392
Path: <sip:proxy.example.net;lr>
Service-Route: <sip:proxy.example.net;lr>
Contact: <sip:ua.example.com>
;expires=3600
;+sip.instance="<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
;gruu="sip:user_aor_1@example.net;opaque=hha9s8d-999a"
P-Associated-URI: <sip:user_aor_2@example.net>,
<sip:+358504821437@example.net;user=phone>
Content-Length: 0
The UA then subscribes to the 'reg' event package as follows:
SUBSCRIBE sip:user_aor_1@example.net SIP/2.0
From: <sip:user_aor_1@example.net>;tag=27182
To: <sip:user_aor_1@example.net>
Route: <sip:proxy.example.net;lr>
Event: reg
Expires: 3600
Accept: application/reginfo+xml
Contact: <sip:user_aor_1@example.net;opaque=hha9s8d-999a>
Content-Length: 0
(The successful response to the subscription is not shown.) Once the
subscription is established an initial notification is sent giving
registration status. In IMS deployments the response includes, in
addition to the status for the requested URI, the status for the
other associated URIs.
NOTIFY sip:user_aor_1@example.net;opaque=hha9s8d-999a SIP/2.0
From: <sip:user_aor_1@example.net>;tag=27182
To: <sip:user_aor_1@example.net>;tag=262281
Subscription-State: active;expires=3600
Event: reg
Content-Type: application/reginfo+xml
Contact: <sip:registrar.example.net>
Content-Length: (...)
<?xml version="1.0"?>
<reginfo xmlns="urn:ietf:params:xml:ns:reginfo"
xmlns:gr="urn:ietf:params:xml:ns:gruuinfo"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
version="1" state="full">
<registration aor="sip:user_aor_1@example.net" id="a7"
state="active">
<contact id="92" state="active" event="registered"
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duration-registered="1" expires="3599">
<uri>
sip:ua.example.com
</uri>
<unknown-param name="+sip.instance">
"<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
</unknown-param>
<allOneLine>
<gr:gruu>sip:user_aor_1@example.net
;opaque=hha9s8d-999a</gruu>
</allOneLine>
</contact>
</registration>
<registration aor="sip:user_aor_2@example.net" id="a8"
state="active">
<contact id="93" state="active" event="created"
duration-registered="1" expires="3599">
<uri>
sip:ua.example.com
</uri>
<unknown-param name="+sip.instance">
"<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
</unknown-param>
<allOneLine>
<gr:gruu>sip:user_aor_2@example.net
;opaque=hha9s8d-999b</gruu>
</allOneLine>
</contact>
</registration>
<registration
aor="sip:+358504821437@example.net;user=phone"
id="a9"
state="active">
<contact id="94" state="active" event="created"
duration-registered="1" expires="3599">
<uri>
sip:ua.example.com
</uri>
<unknown-param name="+sip.instance">
"<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
</unknown-param>
<allOneLine>
<gr:gruu>sip:+358504821437@example.net;user=phone
;opaque=hha9s8d-999c</gruu>
</allOneLine>
</contact>
</registration>
</reginfo>
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The status indicates that the associated URIs all have the same
contact registered. It also includes the unique GRUU that has been
assigned to each. The UA may then retain those GRUUs for use when
establishing dialogs using the corresponding AORs.
8. XML Schema Definition
A gruu document is an XML document that MUST be well-formed and
SHOULD be valid. Gruu documents MUST be based on XML 1.0 and MUST be
encoded using UTF-8. This specification makes use of XML namespaces
for identifying gruu documents. The namespace URI for elements
defined for this purpose is a URN, using the namespace identifier
'ietf'. This URN is:
urn:ietf:params:xml:ns:gruuinfo
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="urn:ietf:params:xml:ns:gruuinfo"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:tns="urn:ietf:params:xml:ns:gruuinfo">
<xs:element name="gruu" type="xs:anyURI"/>
</xs:schema>
9. IANA Considerations
This document calls for IANA to register a new XML namespace URN and
schema per [3].
URI: The URI for this namespace is urn:ietf:params:xml:ns:gruuinfo
Registrant Contact: IETF, SIPPING working group, <sipping@ietf.org>,
Paul Kyzivat <pkyzivat@cisco.com>
XML:
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BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Reg Information GRUU Extension Namespace</title>
</head>
<body>
<h1>Namespace for Reg Information GRUU Extension</h1>
<h2>urn:ietf:params:xml:ns:gruuinfo</h2>
<p>See <a href="[URL of published RFC]">RFCXXXX [[NOTE
TO RFC-EDITOR/IANA: Please replace XXXX with the RFC Number of
this specification]]</a>.</p>
</body>
</html>
END
10. Security Considerations
Security considerations for the registration event package is
discussed in RFC 3680 [1], and those considerations apply here.
The addition of gruu information does not impact security negatively
because the gruu is less sensitive than the contact URI itself.
11. Acknowledgements
The author would like to thank Jonathan Rosenberg for encouraging
this draft.
12. References
12.1. Normative References
[1] Rosenberg, J., "A Session Initiation Protocol (SIP) Event
Package for Registrations", RFC 3680, March 2004.
[2] Rosenberg, J., "Obtaining and Using Globally Routable User Agent
(UA) URIs (GRUU) in the Session Initiation Protocol (SIP)",
draft-ietf-sip-gruu-05 (work in progress), September 2005.
[3] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
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January 2004.
12.2. Informative References
[4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[5] Garcia-Martin, M., Henrikson, E., and D. Mills, "Private Header
(P-Header) Extensions to the Session Initiation Protocol (SIP)
for the 3rd-Generation Partnership Project (3GPP)", RFC 3455,
January 2003.
[6] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating User
Agent Capabilities in the Session Initiation Protocol (SIP)",
RFC 3840, August 2004.
[7] Sparks, R., "Session Initiation Protocol Torture Test Messages",
draft-ietf-sipping-torture-tests-07 (work in progress),
May 2005.
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Author's Address
Paul H. Kyzivat
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
USA
Email: pkyzivat@cisco.com
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