draft-ietf-sipcore-reason-q850-loc-04.txt   draft-ietf-sipcore-reason-q850-loc-05.txt 
Sipcore R. Jesske Sipcore R. Jesske
Internet-Draft Deutsche Telekom Internet-Draft Deutsche Telekom
Updates: RFC3326 (if approved) August 20, 2018 Updates: 3326 (if approved) January 16, 2019
Intended status: Standards Track Intended status: Standards Track
Expires: February 21, 2019 Expires: July 20, 2019
ISUP Cause Location Parameter for the SIP Reason Header Field ISUP Cause Location Parameter for the SIP Reason Header Field
draft-ietf-sipcore-reason-q850-loc-04.txt draft-ietf-sipcore-reason-q850-loc-05.txt
Abstract Abstract
The SIP Reason header field is defined for carrying ISDN User Part The SIP Reason header field is defined for carrying ISDN User Part
(ISUP) cause values as well as SIP response codes. Some services in (ISUP) cause values as well as SIP response codes. Some services in
SIP networks may need to know the ISUP location where the call was SIP networks may need to know the ISUP location where the call was
released in the PSTN network to correctly interpret the reason of released in the PSTN network to correctly interpret the reason of
release. release. This document will update [RFC3326].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 4 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8.1. Registration of location Parameter for Reason header 8.1. Registration of location Parameter for Reason header
field . . . . . . . . . . . . . . . . . . . . . . . . . . 5 field . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
10. Normative References . . . . . . . . . . . . . . . . . . . . 5 10. Normative References . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The SIP Reason header field specification [RFC3326] describes a SIP The SIP Reason header field specification [RFC3326] describes a SIP
header field that is used to indicate that a SIP request is carrying header field that is used to indicate that a SIP request is carrying
the reason of release. It may be an SIP response or ISUP release the reason of release. The reason of release does indicate why a SIP
cause as specified within [Q.850]. [RFC3326] does specify that a Dialog or an PSTN call, in case where the call was interworked to the
ISUP [Q.850] cause code can be carried within a SIP response. The PSTN, was terminated. This may be a normal termination or a
[Q.850] location information identifies the part of the ISUP network termination based on a failure within an entity or other reasons like
where the call was released. congestion. The reason may be an SIP response or ISUP release cause
as specified within [Q.850]. [RFC3326] specifies that a ISUP [Q.850]
cause code can be carried within a SIP response, but not the Q.850
location information. The [Q.850] location information identifies
the part of the ISUP network where the call was released.
This document adds a location value parameter to the reason-extension This document adds a location value parameter to the reason-extension
parameter in [RFC3326] so that the [Q.850] location value can be parameter in [RFC3326] so that the [Q.850] location value can be
interworked from the PSTN. The interworking from PTSN needs only to interworked from the PSTN. The interworking from PTSN needs only to
include the location received by the interworking gateway. include the location received by the interworking gateway. [Q.850]
describes the definition of cause code values and locations used in
ISDN and DSS1 environment. The cause code is used for identifying
the reason of release of a call and the location identifies where the
call was released.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Rationale 3. Rationale
The primary intent of the parameter defined in this specification is The primary intent of the parameter defined in this specification is
for use in IMS (IP Multimedia Subsystem) networks defined by 3GPP but for use in IMS (IP Multimedia Subsystem) networks defined by 3GPP but
also open to be used by any other network. The purpose of this also open to be used by any other network. The purpose of this
parameter is to transport the location of call release from the parameter is to transport the location of call release from the
originating PSTN entity to the SIP entity receiving the response or originating PSTN entity to the SIP entity receiving the response or
BYE message containing the location of the call release. The ISDN BYE message containing the location of the call release. The ISDN
location is defined in [Q.850]. location is defined in [Q.850].
4. Mechanism 4. Mechanism
As defined by [RFC3326] a Reason header field MAY appear in any As defined by [RFC3326] a Reason header field MAY appear in any
request in a dialog, in any CANCEL request and in any response whose request in a dialog, in any CANCEL request and in any response whose
status code explicitly allows the presence of this header field. The status code explicitly allows the presence of this header field. The
syntax of the header field follows the standard SIP parameter syntax. syntax of the header field follows the standard SIP parameter syntax.
The mechanism employed adds a parameter with the ISUP location value This specification adds a parameter with the ISUP location value
defined in [Q.850] to the Reason header field that identifies the defined in [Q.850] to the Reason header field that identifies the
[Q.850] location of the call release in ISUP as defined in [Q.850] . location of the call release in ISUP. The location is a 4 bit value
The location is a 4 bit value which reflects the possible locations which reflects the possible locations where an ISUP call is released.
where an ISUP call is released. Some values are spare or reserved Some values are spare or reserved for national use. The Augmented
for national use. The Augmented BNF (ABNF) [RFC5234] for this BNF (ABNF) [RFC5234] for this parameter is shown in Figure 1.
parameter is shown in Figure 1.
reason-extension =/ isup-cause-location reason-extension =/ isup-cause-location
isup-cause-location = "location" EQUAL string isup-cause-location = "location" EQUAL string
The following values shall be used as location: The following values SHALL be used as location:
U for 0 0 0 0 user U for 0 0 0 0 user
LPN for 0 0 0 1 private network serving the local user LPN for 0 0 0 1 private network serving the local user
LN for 0 0 1 0 public network serving the local user LN for 0 0 1 0 public network serving the local user
TN for 0 0 1 1 transit network TN for 0 0 1 1 transit network
RLN for 0 1 0 0 public network serving the remote user RLN for 0 1 0 0 public network serving the remote user
RPN for 0 1 0 1 private network serving the remote user RPN for 0 1 0 1 private network serving the remote user
LOC-6 for 0 1 1 0 spare LOC-6 for 0 1 1 0 spare
INTL for 0 1 1 1 international network INTL for 0 1 1 1 international network
LOC-8 for 1 0 0 0 spare LOC-8 for 1 0 0 0 spare
LOC-9 for 1 0 0 1 spare LOC-9 for 1 0 0 1 spare
skipping to change at page 3, line 48 skipping to change at page 4, line 31
LOC-12 for 1 1 0 0 reserved for national use LOC-12 for 1 1 0 0 reserved for national use
LOC-13 for 1 1 0 1 reserved for national use LOC-13 for 1 1 0 1 reserved for national use
LOC-14 for 1 1 1 0 reserved for national use LOC-14 for 1 1 1 0 reserved for national use
LOC-15 for 1 1 1 1 reserved for national use LOC-15 for 1 1 1 1 reserved for national use
Figure 1: isup-cause-location Figure 1: isup-cause-location
Note: These are the values defined within [Q.850] as location. Thus Note: These are the values defined within [Q.850] as location. Thus
other values are not within the scope of this document. other values are not within the scope of this document.
Depending on the direction the UAC or UAS shall include the location Depending on whether the message is a request or a response the UAC
parameter when setting up the Reason header field with a [Q.850] or UAS SHALL include the location parameter when setting up the
cause. This approach is only valid in cases when the ISUP [Q.850] Reason header field with a [Q.850] cause. This approach is only
location is available. possible in cases when the ISUP [Q.850] location is available.
The use of the location parameter is restricted to Q850 cause values The use of the location parameter is restricted to Q850 cause values.
in other cases the location, if present, MUST be silently ignored. Other values MUST be ignored if present.
5. Example 5. Example
The following example shows a SIP 404 response message containing a The following example shows a SIP 404 response message containing a
Reason header field with a [Q.850] cause value and a isup-cause- Reason header field with a [Q.850] cause value and a isup-cause-
location value. The 404 Response will be set up when a gateway location value. The 404 Response will be sent when a gateway
receives an ISUP Release with a [Q.850] cause set to 1 meaning receives an ISUP Release with a [Q.850] cause set to 1, meaning
"Unallocated (unassigned) number", i.e. the number is not known in "Unallocated (unassigned) number", i.e. the number is not known in
the PSTN. the PSTN.
SIP/2.0 404 Not Found SIP/2.0 404 Not Found
From: Alice <sips:alice@atlanta.example.com>;tag=1234567 From: Alice <sips:alice@atlanta.example.com>;tag=1234567
To: Bob <sips:bob@biloxi.example.com>;tag=765432 To: Bob <sips:bob@biloxi.example.com>;tag=765432
Call-ID: 12345600@atlanta.example.com Call-ID: 12345600@atlanta.example.com
CSeq: 1 INVITE CSeq: 1 INVITE
Reason: Q.850;cause=1;text="Unallocated (unassigned) number"; Reason: Q.850;cause=1;text="Unallocated (unassigned) number";
location=LN location=LN
Content-Length: 0 Content-Length: 0
Figure 2: Example Location in Reason header field. Figure 2: Example Location in Reason header field.
6. Privacy Considerations 6. Privacy Considerations
This document doesn't change any of the privacy considerations While the addition of the location parameter does provide an
described in [RFC3326]. While the addition of the location parameter indicator of the entity that added the location in the signaling path
does provide an indicator of the entity that added the location in this provides little more exposure than the [Q.850] cause itself.
the signaling path this provides little more exposure than the When applying privacy according to [RFC3323] the location value will
[Q.850] cause itself. not give any hint to the identity originating or terminating party of
the call. It shows only the location of the release of the call
which maybe the end device itself (location user) or any other
network part. The location is even not showing from which city or
town the call is coming from.
7. Security Considerations 7. Security Considerations
This document doesn't change any of the security considerations This document doesn't change any of the security considerations
described in [RFC3326]. The addition of the location parameter does described in [RFC3326]. The addition of the location parameter does
provide an indicator of the [Q.850] location where the call was provide an indicator of the [Q.850] location where the call was
released within the PSTN. This information may be used for specific released within the PSTN. This information may be used for specific
location driven services but does not create any additional security location driven services but does not create any additional security
constrains. But since the [Q.850] location is very imprecise the constrains. But since the [Q.850] location is very imprecise the
[Q.850] location value itself will not add any major security [Q.850] location value itself will not add any major security
constraint. The use of this parameter is not restricted to a constraint. The use of this parameter is not restricted to a
specific architecture. specific architecture.
[RFC3398] does an extensive security consideration due to
interworking between ISUP and SIP. Beyond these considerations the
addition of the location does not add additional security concerns.
The location shows the network part where the call is released.
Knowing this does not increase the possibilities of extended fraud
scenarios.
8. IANA Considerations 8. IANA Considerations
8.1. Registration of location Parameter for Reason header field 8.1. Registration of location Parameter for Reason header field
This document calls for IANA to register a new SIP header parameter This document calls for IANA to register a new SIP header parameter
as per the guidelines in [RFC3968], which will be added to Header as per the guidelines in [RFC3968], which will be added to Header
Field Parameters sub-registry under http://www.iana.org/assignments/ Field Parameters sub-registry under http://www.iana.org/assignments/
sip-parameters. sip-parameters.
Header Field: Reason Header Field: Reason
Parameter Name: location Parameter Name: location
Predefined Values: yes
Reference: RFCXXXX
Note to RFC Editor: Please replace RFC XXXX with the RFC number of
this specification.
9. Acknowledgments 9. Acknowledgments
Thanks to Michael Kreipl, Thoams Belling, Marianne Mohali, Peter Thanks to Michael Kreipl, Thoams Belling, Marianne Mohali, Peter
Daws, Paul Kyzivat, Dale Worley, Yehoshua Gev, Keith Drage for the Daws, Paul Kyzivat, Dale Worley, Yehoshua Gev, Keith Drage for the
comments and review. comments and review.
10. Normative References 10. Normative References
[Q.850] INTERNATIONAL TELECOMMUNICATION UNION, "Usage of cause and [Q.850] INTERNATIONAL TELECOMMUNICATION UNION, "Usage of cause and
location in the Digital Subscriber Signalling System No. 1 location in the Digital Subscriber Signalling System No. 1
skipping to change at page 5, line 42 skipping to change at page 6, line 49
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC3323] Peterson, J., "A Privacy Mechanism for the Session
Initiation Protocol (SIP)", RFC 3323,
DOI 10.17487/RFC3323, November 2002,
<https://www.rfc-editor.org/info/rfc3323>.
[RFC3326] Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason [RFC3326] Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason
Header Field for the Session Initiation Protocol (SIP)", Header Field for the Session Initiation Protocol (SIP)",
RFC 3326, DOI 10.17487/RFC3326, December 2002, RFC 3326, DOI 10.17487/RFC3326, December 2002,
<https://www.rfc-editor.org/info/rfc3326>. <https://www.rfc-editor.org/info/rfc3326>.
[RFC3398] Camarillo, G., Roach, A., Peterson, J., and L. Ong,
"Integrated Services Digital Network (ISDN) User Part
(ISUP) to Session Initiation Protocol (SIP) Mapping",
RFC 3398, DOI 10.17487/RFC3398, December 2002,
<https://www.rfc-editor.org/info/rfc3398>.
[RFC3968] Camarillo, G., "The Internet Assigned Number Authority [RFC3968] Camarillo, G., "The Internet Assigned Number Authority
(IANA) Header Field Parameter Registry for the Session (IANA) Header Field Parameter Registry for the Session
Initiation Protocol (SIP)", BCP 98, RFC 3968, Initiation Protocol (SIP)", BCP 98, RFC 3968,
DOI 10.17487/RFC3968, December 2004, DOI 10.17487/RFC3968, December 2004,
<https://www.rfc-editor.org/info/rfc3968>. <https://www.rfc-editor.org/info/rfc3968>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008, DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>. <https://www.rfc-editor.org/info/rfc5234>.
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