draft-ietf-mmusic-sdp-cs-00.txt   draft-ietf-mmusic-sdp-cs-01.txt 
MMUSIC WG M. Garcia-Martin MMUSIC WG M. Garcia-Martin
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track S. Veikkolainen Intended status: Standards Track S. Veikkolainen
Expires: August 29, 2009 Nokia Expires: December 19, 2009 Nokia
February 25, 2009 June 17, 2009
Session Description Protocol (SDP) Extension For Setting Up Audio Media Session Description Protocol (SDP) Extension For Setting Up Audio Media
Streams Over Circuit-Switched Bearers In The Public Switched Telephone Streams Over Circuit-Switched Bearers In The Public Switched Telephone
Network (PSTN) Network (PSTN)
draft-ietf-mmusic-sdp-cs-00 draft-ietf-mmusic-sdp-cs-01
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 29, 2009. This Internet-Draft will expire on December 19, 2009.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 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 in effect on the date of
(http://trustee.ietf.org/license-info) in effect on the date of publication of this document (http://trustee.ietf.org/license-info).
publication of this document. Please review these documents Please review these documents carefully, as they describe your rights
carefully, as they describe your rights and restrictions with respect and restrictions with respect to this document.
to this document.
Abstract Abstract
This memo describes use cases, requirements, and protocol extensions This memo describes use cases, requirements, and protocol extensions
for using the Session Description Protocol (SDP) Offer/Answer model for using the Session Description Protocol (SDP) Offer/Answer model
for establishing audio media stream over circuit-switched bearers in for establishing audio media stream over circuit-switched bearers in
the Public Switched Telephone Network (PSTN). the Public Switched Telephone Network (PSTN).
Table of Contents Table of Contents
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5.2.1. Connection Data . . . . . . . . . . . . . . . . . . . 8 5.2.1. Connection Data . . . . . . . . . . . . . . . . . . . 8
5.2.2. Media Descriptions . . . . . . . . . . . . . . . . . . 9 5.2.2. Media Descriptions . . . . . . . . . . . . . . . . . . 9
5.2.3. Correlating the PSTN Circuit-Switched Bearer with 5.2.3. Correlating the PSTN Circuit-Switched Bearer with
SDP . . . . . . . . . . . . . . . . . . . . . . . . . 10 SDP . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2.3.1. The "correlation" attribute . . . . . . . . . . . 11 5.2.3.1. The "correlation" attribute . . . . . . . . . . . 11
5.2.3.2. Caller-ID Correlation Mechanism . . . . . . . . . 11 5.2.3.2. Caller-ID Correlation Mechanism . . . . . . . . . 11
5.2.3.3. User-User Information Element Correlation 5.2.3.3. User-User Information Element Correlation
Mechanism . . . . . . . . . . . . . . . . . . . . 12 Mechanism . . . . . . . . . . . . . . . . . . . . 12
5.2.3.4. DTMF Correlation Mechanism . . . . . . . . . . . . 13 5.2.3.4. DTMF Correlation Mechanism . . . . . . . . . . . . 13
5.2.3.5. Negotiating the used correlation mechanisms . . . 15 5.2.3.5. Negotiating the used correlation mechanisms . . . 15
5.3. Considerations for Usage of Existing SDP . . . . . . . . . 16 5.3. Considerations for Usage of Existing SDP . . . . . . . . . 17
5.3.1. Originator of the Session . . . . . . . . . . . . . . 16 5.3.1. Originator of the Session . . . . . . . . . . . . . . 17
5.3.2. Contact information . . . . . . . . . . . . . . . . . 17 5.3.2. Contact information . . . . . . . . . . . . . . . . . 17
5.3.3. Determining the Direction of the Circuit-Switched 5.3.3. Determining the Direction of the Circuit-Switched
Connection Setup . . . . . . . . . . . . . . . . . . . 17 Connection Setup . . . . . . . . . . . . . . . . . . . 17
5.4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . 18 5.4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . 18
6. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . . 19 6. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. Basic SDP example: Single Circuit-Switched Audio Stream . 19 6.1. Basic SDP example: Single Circuit-Switched Audio Stream . 19
6.2. Advanced SDP example: Alternative and IP 6.2. Advanced SDP example: Alternative and IP
Circuit-Switched Audio Streams . . . . . . . . . . . . . . 20 Circuit-Switched Audio Streams . . . . . . . . . . . . . . 20
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
7.1. Registration of new correlation SDP attribute . . . . . . 22 7.1. Registration of new correlation SDP attribute . . . . . . 22
7.2. Registration of a new "nettype" value . . . . . . . . . . 22 7.2. Registration of a new "nettype" value . . . . . . . . . . 22
7.3. Registration of new "addrtype" values . . . . . . . . . . 22 7.3. Registration of new "addrtype" values . . . . . . . . . . 22
7.4. Registration of a new "proto" value . . . . . . . . . . . 22 7.4. Registration of a new "proto" value . . . . . . . . . . . 22
8. Security Considerations . . . . . . . . . . . . . . . . . . . 23 8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10.1. Normative References . . . . . . . . . . . . . . . . . . . 23 10.1. Normative References . . . . . . . . . . . . . . . . . . . 23
10.2. Informative References . . . . . . . . . . . . . . . . . . 23 10.2. Informative References . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
The Session Description Protocol (SDP) [RFC4566] is intended for The Session Description Protocol (SDP) [RFC4566] is intended for
describing multimedia sessions for the purposes of session describing multimedia sessions for the purposes of session
announcement, session invitation, and other forms of multimedia announcement, session invitation, and other forms of multimedia
session initiation. SDP is most commonly used for describing media session initiation. SDP is most commonly used for describing media
streams that are transported over the Real-Time Transport Protocol streams that are transported over the Real-Time Transport Protocol
(RTP) [RFC3550], using the profiles for audio and video media defined (RTP) [RFC3550], using the profiles for audio and video media defined
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correlation mechanism will succeed even if the usage of those was correlation mechanism will succeed even if the usage of those was
agreed beforehand. This is due to the fact that the correlation agreed beforehand. This is due to the fact that the correlation
mechanisms require support from the circuit-switched bearer mechanisms require support from the circuit-switched bearer
technology used. technology used.
Therefore, even a single positive indication using any of these Therefore, even a single positive indication using any of these
mechanisms SHOULD be interpreted by the passive endpoint so that the mechanisms SHOULD be interpreted by the passive endpoint so that the
circuit-switched bearer establishment is related to the ongoing circuit-switched bearer establishment is related to the ongoing
session, even if the other correlation mechanisms fail. session, even if the other correlation mechanisms fail.
If, after negotiating one or more correlation mechanisms in the SDP
offer/answer exchange, an endpoint receives a circuit-switched call
with no correlation information present, the endpoint has two
choices: it can either treat the call as unrelated, or treat the call
as related to the ongoing session in the IP domain.
An endpoint may for example specify a time window after SDP offer/
answer exchange during which received calls are treated as correlated
even if the signalling in the circuit-switched domain does not carry
any correlation information. In this case, there is a chance that
the call is erroneously treated as related to the ongoing session.
An endpoint may also choose to always treat an incoming call as
unrelated if the signalling in the circuit-switched domain does not
carry any correlation information. In this case, there is a chance
that the call is erroneously treated as unrelated.
Since, in these cases, no correlation information can be deduced from
the signalling, it is up to the implementation to decide how to
behave. One option is also to let the user decide whether to accept
the call as related, or to treat the call as unrelated.
5.3. Considerations for Usage of Existing SDP 5.3. Considerations for Usage of Existing SDP
5.3.1. Originator of the Session 5.3.1. Originator of the Session
According to SDP [RFC4566], the origin line in SDP has the following According to SDP [RFC4566], the origin line in SDP has the following
syntax: syntax:
o=<username> <sess-id> <sess-version> <nettype> <addrtype> o=<username> <sess-id> <sess-version> <nettype> <addrtype>
<unicast-address> <unicast-address>
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Type SDP Name Reference Type SDP Name Reference
-------------- --------------------------- --------- -------------- --------------------------- ---------
proto PSTN [RFCxxxx] proto PSTN [RFCxxxx]
8. Security Considerations 8. Security Considerations
This document provides an extension on top of RFC 4566 [RFC4566], and This document provides an extension on top of RFC 4566 [RFC4566], and
RFC 3264 [RFC3264]. As such, the security considerations of those RFC 3264 [RFC3264]. As such, the security considerations of those
documents apply. documents apply.
This memo provides mechanisms to agree on a correlation identifier or
identifiers that are used to evaluate whether an incoming circuit-
switched call is related to an ongoing session in the IP domain. If
an attacker replicates the correlation identifer and establishes a
call within the time window the receiving endpoint is expecting a
call, the attacker may be able to hijack the circuit-switched call.
These types of attacks are not specific to the mechanisms presented
in this memo. For example, caller ID spoofing is a well known attack
in the PSTN. Users are advised to use the same caution before
revealing sensitive information as they would on any other phone
call.
9. Acknowledgments 9. Acknowledgments
The authors want to thank Flemming Andreasen, Thomas Belling, Jari The authors want to thank Flemming Andreasen, Thomas Belling, Jari
Mutikainen, Miikka Poikselka, Jonathan Rosenberg, Ingemar Johansson, Mutikainen, Miikka Poikselka, Jonathan Rosenberg, Ingemar Johansson,
Christer Holmberg, and Alf Heidermark for providing their insight and Christer Holmberg, and Alf Heidermark for providing their insight and
comments on this document. comments on this document.
10. References 10. References
10.1. Normative References 10.1. Normative References
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[I-D.garcia-mmusic-sdp-misc-cap] [I-D.garcia-mmusic-sdp-misc-cap]
Garcia, M., Veikkolainen, S., and R. Gilman, Garcia, M., Veikkolainen, S., and R. Gilman,
"Miscellaneous Capabilities Negotiation in the Session "Miscellaneous Capabilities Negotiation in the Session
Description Protocol (SDP)", Description Protocol (SDP)",
draft-garcia-mmusic-sdp-misc-cap-00 (work in progress), draft-garcia-mmusic-sdp-misc-cap-00 (work in progress),
October 2008. October 2008.
[I-D.ietf-mmusic-sdp-capability-negotiation] [I-D.ietf-mmusic-sdp-capability-negotiation]
Andreasen, F., "SDP Capability Negotiation", Andreasen, F., "SDP Capability Negotiation",
draft-ietf-mmusic-sdp-capability-negotiation-09 (work in draft-ietf-mmusic-sdp-capability-negotiation-10 (work in
progress), July 2008. progress), May 2009.
[I-D.ietf-mmusic-sdp-media-capabilities] [I-D.ietf-mmusic-sdp-media-capabilities]
Gilman, R., Even, R., and F. Andreasen, "SDP media Gilman, R., Even, R., and F. Andreasen, "SDP media
capabilities Negotiation", capabilities Negotiation",
draft-ietf-mmusic-sdp-media-capabilities-06 (work in draft-ietf-mmusic-sdp-media-capabilities-07 (work in
progress), January 2009. progress), February 2009.
[ITU.E164.1991] [ITU.E164.1991]
International Telecommunications Union, "The International International Telecommunications Union, "The International
Public Telecommunication Numbering Plan", ITU- Public Telecommunication Numbering Plan", ITU-
T Recommendation E.164, 1991. T Recommendation E.164, 1991.
[ITU.Q931.1998] [ITU.Q931.1998]
"Digital Subscriber Signalling System No. 1 (DSS 1) - ISDN "Digital Subscriber Signalling System No. 1 (DSS 1) - ISDN
User - Network Interface Layer 3 Specification for Basic User - Network Interface Layer 3 Specification for Basic
Call Control", ISO Standard 9594-1, May 1998. Call Control", ISO Standard 9594-1, May 1998.
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