SIP Gerhard Ott
Internet Draft Martin Huelsemann
Expires: January 2008 Deutsche Telekom
Intended Status: private
Document: draft-ott-sip-serv-indication-notification-00
Expires: December 2007 June 2007
Private Header (P-Header) Extensions to the Session Initiation
Protocol (SIP) for the support of the Services for the
European Telecommunications Standards Institute,
draft-ott-sip-serv-indication-notification-00
Status of this Memo
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document describes a set of private Session Initiation
Protocol (SIP) headers (P-headers) used in ETSI Next Generation
Networks (NGN), along with their applicability, which is limited to
particular environments. The P-headers defined in the present
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document are for the purpose of providing indications and
notifications for services used within the ETSI NGN.
Table of Contents
Status of this Memo.........................................1
Abstract................................................. .1
Table of Contents....................................... ...2
1. Overview............................................ ....3
2. Overall Applicability.............................. .....3
3. Terminology......................................... ....3
4. SIP Private Headers......................................3
4.1 The P-Service-Notification header.......................3
4.2 The P-Service-Indication header ........................4
5. Formal Syntax...................................... .....5
5.1 P-Service-Notification header syntax....................5
5.2 P-Service-Indication header syntax......................6
5.3 Table of new headers....................................6
6. Security Considerations..................................6
6.1 P-Service-Notification header...........................6
6.2 P-Service-Indication header.............................7
7. IANA Considerations......................................7
8. References.......................................... ....7
8.1 Normative References....................................7
8.2 Informative References..................................7
9. Authors' Addresses.......................................8
10. Acknowledgments.........................................8
Full Copyright Statement....................................8
Intellectual Property.......................................8
Acknowledgment........................................ .....9
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1. Overview
The European Telecommunications Standards Institute (ETSI)
Telecommunications and Internet converged Services and Protocols
for Advanced Networking (TISPAN) is defining the release 2 of the
TISPAN Next Generation Network (NGN) aiming at the creation of a
multimedia fixed network. Generally NGN is based on the 3rd
Generation mobile Partnership Project (3GPP) IP Multimedia
Subsystem (IMS) Release 7 with additions required to support the
fixed access.
While ETSI is committed to the creation of new multimedia
applications and services, the importance of providing support to
existing Integrated Services Digital Network and Public Switched
Telephone Network (ISDN/PSTN) supplementary services has also been
acknowledged.
2. Overall Applicability
The SIP extensions specified in this document make certain
assumptions regarding network topology, linkage between SIP and
lower layers, and the availability of transitive trust. These
assumptions are generally NOT APPLICABLE in the Internet as a
whole. The mechanisms specified here were designed to satisfy
service specific requirements specified in the release 2 of the
TISPAN Next Generation Network (NGN) on SIP [4] for which either no
general-purpose solution was planned, where insufficient
operational experience was available to understand if a general
solution is needed, or where a more general solution is not yet
mature. For more details about the assumptions made about these
extensions, consult the Applicability subsection for each
extension.
3. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",
"MAY",and "OPTIONAL" are to be interpreted as described in RFC 2119
[9] and indicate requirement levels for compliant implementations.
4. SIP Private Headers
4.1 The P-Service-Notification header
This extension allows an entity to send a notification about
service specific information to a user. The P-Service-Notification
header can be used in SIP requests as well as in responses. This
requirement is stated in the TISPAN requirements on SIP [2].
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A typical deployment situation occurs when a SIP request arrives at
the UAS and a service conditioned notification needs to be sent
back to the UAC. An example for this is when an INVITE request
arrives at a callee who is already involved in a call, and the
callee wants to inform the caller that this call is a waiting call.
4.1.1 Applicability statement for the P-Service-Notification header
The P-Service-Notification is applicable when an entity needs to
notify an UA about the status of a service applied by this entity.
4.1.2 Usage of the P-Service-Notification header
The P-Service-Notification header field provides an UA with the
status of a service of that moment when the information is sent.
This information is intended to be rendered to the user.
4.1.2.1 Procedures at the UA
A UAC MAY insert a P-Service-Notification header field with a value
according to the service currently applied in any SIP request or
response.
A UAS may insert a P-Service-Notification header field with a value
according to the service currently applied in any SIP request or
response.
4.1.2.2 Procedures at the proxy
A proxy may insert a P-Service-Notification header field with a
value according to the service currently applied in any SIP request
or response.
4.2 The P-Service-Indication header
This extension allows an entity to send an indication about service
specific proceeding required for the applied service to a UA or a
proxy. The P-Service-Indication header can be used in SIP requests
as well as in responses. This requirement is stated in the TISPAN
requirements on SIP [2].
A typical deployment situation occurs when a SIP request arrives at
a proxy and an indication for a service specific proceeding of this
request needs to be send to the UA. An example for this is when an
INVITE request arrives at a proxy with the function of an
application server that is in control of network resources and
needs to indicate to the callee that he should release consumed
resources before accepting this call.
4.2.1 Applicability statement for the P-Service-Indication header
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The P-Service-Indication header is applicable when an entity needs
to indicate a service specific proceeding of a request or a
response to an UA or a proxy.
4.2.2 Usage of the P-Service-Indication header
The P-Service-Indication header field provides an UA or a proxy
with an indication how to proceed the SIP request or response in
the context of a specific service.
4.2.2.1 Procedures at the UA
A UAC MAY insert a P-Service-Indication header field with a value
according to the service currently applied in any SIP request or
response.
A UAS may insert a P-Service-Indication header field with a value
according to the service currently applied in any SIP request or
response.
4.2.2.2 Procedures at the proxy
A proxy may insert a P-Service-Indication header field with a value
according to the service currently applied in any SIP request or
response.
5. Formal Syntax
All of the mechanisms specified in this document are described in
both prose and an augmented Backus-Naur Form (BNF) defined in RFC
2234 [3]. Further, several BNF definitions are inherited from SIP
and are not repeated here. Implementers need to be familiar with
the notation and contents of SIP [1] and RFC 2234 [3] to understand
this document.
5.1 P-Service-Notification header syntax
The following summarizes the syntax of the P-Service-Notification,
based upon the standard SIP syntax [RFC 3261]
P-Service-Notification = "P-Service-Notification"
HCOLON notification
notification = "user-suspended" /"user-resumed" /
"conference-established" /
"conference-disconnected" /
"other-party-added" /
"isolated" / "reattached" /
"other-party-isolated" /
"other-party-reattached" /
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"other-party-split" /
"other-party-disconnected" /
"conference-floating" /
"call-is-a-waiting call" /
"diversion-activated" /
"call-transfer-alerting" /
"call-transfer-active" / "remote-hold" /
"remote-retrieval" / "call-is-diverting" /
TOKEN
5.2 P-Service-Indication header syntax
The following summarizes the syntax of the P-Service-Indication,
based upon the standard SIP syntax [RFC 3261]
P-Service-Indication = "P-Service-Indication"
HCOLON indication
Indication = "CW" /"CCBS" / "CCNR" / TOKEN
5.3 Table of new headers
Table 1 extends the headers defined in this document to Table 2 in
SIP [1], section 7.1 of the SIP-specific event notification [6],
tables 1 and 2 in the SIP INFO method [8], tables 1 and 2 in
Reliability of provisional responses in SIP [7], tables 1 and 2 in
the SIP UPDATE method [9], tables 1 and 2 in the SIP extension for
Instant Messaging [10], and table 1 in the SIP REFER method [11]:
Header field where proxy ACK BYE CAN INV OPT REG
___________________________________________________________
P-Service-Notification amdr - - - o - -
P-Service-Indication amdr - - - o - -
Header field SUB NOT PRA INF UPD MSG REF
___________________________________________________________
P-Service-Notification o o - o o - o
P-Service-Indication o o - o o - o
Table 1: Header field support
6. Security Considerations
6.1 P-Service-Notification header
The information returned in the P-Service-Notification header is
not viewed as particularly sensitive. Rather, it is simply
informational in nature. If end-to-end protection is not used at
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the SIP layer, it is possible for proxies to modify the contents of
the header value. This attack, while potentially annoying, should
not have significant impacts.
6.2 P-Service-Indication header
The information returned in the P-Service-Indication header is
viewed as particularly sensitive. An indication is sensitive,
potentially private, information. Therefore, indications SHOULD be
sent in such a way to ensure confidentiality, message integrity and
verification of subscriber identity, such as sending indications
using a SIPS URL.
7. IANA Considerations
This document defines several private SIP extension header fields
(beginning with the prefix "P-").
These extension headers have been included in the registry of SIP
header fields defined in SIP [1]. Expert review is required for
this process by the SIP Working Group.
The following extensions are registered as private extension header
fields:
RFC Number: RFCxxx
Header Field Name: P-Service-Notification
Compact Form: none
RFC Number: RFCxxx
Header Field Name: P-Service-Indication
Compact Form: none
8. References
8.1 Normative References
[1] 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.
8.2 Informative References
[2] Jesske, R., "Analysis of the Input Requirements for the
Session Initiation Protocol (SIP) in support for the European
Telecommunications Standards Institute (ETSI) Next Generation
Networks (NGN) simulation service",
draft-jesske-sipping-tispan-analysis-04 (work in progress),
December 2007.
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9. Authors' Addresses
Gerhard Ott
Deutsche Telekom
Hansastrasse 39
90441 Nuernberg
Germany
Email: gerhard.ott@t-com.net
Martin Huelsemann
Deutsche Telekom
Deutsche-Telekom-Allee 1
64307 Darmstadt
Germany
Email: martin.huelsemann@t-com.net
10. Acknowledgments
This draft was motivated based on the requirements in [2].
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