draft-ietf-sipcore-reason-q850-loc-07.txt   rfc8606.txt 
Sipcore R. Jesske Internet Engineering Task Force (IETF) R. Jesske
Internet-Draft Deutsche Telekom Request for Comments: 8606 Deutsche Telekom
Updates: 3326 (if approved) March 13, 2019 Updates: 3326 June 2019
Intended status: Standards Track Category: Standards Track
Expires: September 14, 2019 ISSN: 2070-1721
ISUP Cause Location Parameter for the SIP Reason Header Field ISDN User Part (ISUP) Cause Location Parameter
draft-ietf-sipcore-reason-q850-loc-07.txt for the SIP Reason Header Field
Abstract Abstract
The SIP Reason header field is defined for carrying ISUP (Integrated The SIP Reason header field is defined to carry ISUP (ISDN User Part)
Services Digital Network User Part) cause values as well as SIP cause values as well as SIP response codes. Some services in SIP
response codes. Some services in SIP networks may need to know the networks may need to know the ISUP location where the call was
ISUP location where the call was released in the PSTN network to released in the PSTN (Public Switched Telephone Network) to correctly
correctly interpret the reason of release. This document will update interpret the reason of release. This document updates RFC 3326 by
RFC3326. adding a location parameter for this purpose.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8.1. Registration of location Parameter for Reason header 8.1. Registration of the Location Parameter for the Reason
field . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Header Field . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 9. Normative References . . . . . . . . . . . . . . . . . . . . 6
10. Normative References . . . . . . . . . . . . . . . . . . . . 6 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The SIP Reason header field specification [RFC3326] describes a SIP Section 3.4 of [RFC3326] describes a SIP message flow for canceling
header field that is used to indicate that a SIP request is carrying an INVITE request when a REL (release) message is received from the
the reason of release. The reason of release indicates why a SIP ISUP side. That document specifies the SIP Reason header field
Dialog or a PSTN call, in case where the call was interworked to the [RFC3326] that is used to indicate the reason of release. The reason
PSTN, was terminated. This may be a normal termination or a of release indicates why a SIP Dialog or a PSTN call, in cases where
termination based on a failure within an entity or other reasons like the call was interworked to the PSTN, was terminated. The
congestion. The reason may be an SIP response or ISUP release cause termination may be normal, based on a failure within an entity (e.g.
as specified within [Q.850]. [RFC6432] specifies that a ISUP [Q.850] temporary failure) or caused by other factors (e.g., congestion).
The reason may be a SIP response or an ISUP release cause as
specified within [Q.850]. [RFC6432] specifies that an ISUP [Q.850]
cause code can be carried within a SIP response, but not the Q.850 cause code can be carried within a SIP response, but not the Q.850
location information. The [Q.850] location information identifies location information. The [Q.850] location information identifies
the part of the ISUP network where the call was released. 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 defined in [RFC3326] so that the [Q.850] location value can
interworked from the PSTN. The interworking from PTSN needs only to be interworked from the PSTN. The interworking from the PSTN needs
include the location received by the interworking gateway. [Q.850] only to include the location received by the interworking gateway.
describes the definition of cause code values and locations used in [Q.850] describes the definitions of the cause code values and the
ISDN and DSS1 environment. The cause code is used for identifying locations used in ISDN and DSS1 (Digital Subscriber Signalling System
the reason of release of a call and the location identifies where the No. 1) environments. The cause code is used for identifying the
reason of release of a call, and the location identifies where the
call was released. 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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. 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,
it is also open to be used by any other network that includes ISUP but it is also open to be used by any other networks that include
interworking gateways and uses Q.850 reason codes. The purpose of ISUP interworking gateways and use Q.850 reason codes. The purpose
this parameter is to transport the location of call release from the of this parameter is to hold the location of the call release so that
originating PSTN entity to the SIP entity receiving the response or it can be transported from the originating PSTN entity to the SIP
BYE message containing the location of the call release. The ISDN entity via a response or BYE message. The ISDN location is defined
location is defined in [Q.850]. in [Q.850].
4. Mechanism 4. Mechanism
As defined by [RFC6432] any SIP Response message, with the exception As defined by [RFC6432], any SIP Response message, with the exception
of a 100 (Trying), MAY contain a Reason header field with a Q.850 of 100 (Trying), MAY contain a Reason header field with a Q.850
[Q.850] cause code. [Q.850] cause code.
This specification 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
location of the call release in ISUP. The location is a 4 bit value location of the call release in ISUP. The location is a 4-bit value
which reflects the possible locations where an ISUP call is released. that reflects the possible locations where an ISUP call is released.
Some values are spare or reserved for national use. The Augmented Some values are spare or reserved for national use. The Augmented
BNF (ABNF) [RFC5234] for this parameter is shown in Figure 1. BNF (ABNF) [RFC5234] for this parameter is shown in Figure 1.
reason-extension =/ isup-cause-location reason-extension =/ isup-cause-location
isup-cause-location = "location" EQUAL isup-location-value isup-cause-location = "location" EQUAL isup-location-value
isup-location-value = isup-location-value =
%s"U" / ; for 0 0 0 0 user "U" / ; for 0 0 0 0 user
%s"LPN" / ; for 0 0 0 1 private network serving the local user "LPN" / ; for 0 0 0 1 private network serving the local user
%s"LN" / ; for 0 0 1 0 public network serving the local user "LN" / ; for 0 0 1 0 public network serving the local user
%s"TN" / ; for 0 0 1 1 transit network "TN" / ; for 0 0 1 1 transit network
%s"RLN" / ; for 0 1 0 0 public network serving the remote user "RLN" / ; for 0 1 0 0 public network serving the remote user
%s"RPN" / ; for 0 1 0 1 private network serving the remote user "RPN" / ; for 0 1 0 1 private network serving the remote user
%s"LOC-6" / ; for 0 1 1 0 spare "LOC-6" / ; for 0 1 1 0 spare
%s"INTL" / ; for 0 1 1 1 international network "INTL" / ; for 0 1 1 1 international network
%s"LOC-8" / ; for 1 0 0 0 spare "LOC-8" / ; for 1 0 0 0 spare
%s"LOC-9" / ; for 1 0 0 1 spare "LOC-9" / ; for 1 0 0 1 spare
%s"BI" / ; for 1 0 1 0 network beyond interworking point "BI" / ; for 1 0 1 0 network beyond interworking point
%s"LOC-11" / ; for 1 0 1 1 spare "LOC-11" / ; for 1 0 1 1 spare
%s"LOC-12" / ; for 1 1 0 0 reserved for national use "LOC-12" / ; for 1 1 0 0 reserved for national use
%s"LOC-13" / ; for 1 1 0 1 reserved for national use "LOC-13" / ; for 1 1 0 1 reserved for national use
%s"LOC-14" / ; for 1 1 1 0 reserved for national use "LOC-14" / ; for 1 1 1 0 reserved for national use
%s"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: ABNF for isup-cause-location
Note: These are the values defined within [Q.850] as location. Thus Note: These are the location values defined within [Q.850]. The
other values are not within the scope of this document. 'LOC-*' names are the wire codepoints for the values currently left
as 'spare' or 'reserved' in [Q.850]; these will continue to be the
wire codepoints in the case of future allocation or national usage of
the such values.
Depending on whether the message is a request or a response the UAC The UAC or UAS SHALL include the location parameter in a request or
or UAS SHALL include the location parameter when setting up the response when setting up the Reason header field with a [Q.850] cause
Reason header field with a [Q.850] cause. This approach is only when the ISUP [Q.850] 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 Q.850 cause
Other values MUST be ignored if present. values. 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 an isup-cause-
location value. The 404 Response will be sent 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
the PSTN. PSTN.
SIP/2.0 404 Not Found SIP/2.0 404 Not Found
Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bKx5st Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bKx5st
Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK4321 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK4321
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 of a Location in the Reason Header Field
6. Privacy Considerations 6. Privacy Considerations
While the addition of the location parameter does provide an While the addition of the location parameter provides an indicator of
indicator of the entity that added the location in the signaling path the entity that added the location in the signaling path, it provides
this provides little more exposure than the [Q.850] cause itself. little more exposure than the [Q.850] cause itself. The ISUP
The ISUP location value itself will not reveal the identity of the location value itself will not reveal the identity of the originating
originating or terminating party of the call. It shows only the ISUP or terminating party of the call. It shows only the ISUP network
network location of the device that released the call. The ISUP location of the device that released the call. The ISUP location
location does not show show the physical location of the caller or does not show the physical location of the caller or callee.
callee.
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
provide an indicator of the [Q.850] location where the call was provides 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 constraints. Because 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 constraints. The use of this parameter is not restricted to a
specific architecture. specific architecture.
[RFC3398] describes detailed security consideration due to [RFC3398] describes detailed security considerations due to
interworking between ISUP and SIP. Beyond these considerations the interworking between ISUP and SIP. Beyond these considerations, the
addition of the location does not add additional security concerns. addition of the location does not introduce new security concerns.
The location shows the network part where the call is released. The location shows the network part where the call was released.
Knowing this does not increase the possibilities of extended fraud Knowing this does not increase the possibilities of extended fraud
scenarios. scenarios.
8. IANA Considerations 8. IANA Considerations
8.1. Registration of location Parameter for Reason header field 8.1. Registration of the Location Parameter for the Reason Header Field
This document calls for IANA to register a new SIP header parameter IANA has registered a new SIP header parameter in the "Header Field
as per the guidelines in [RFC3968], which will be added to Header Parameters and Parameter Values" subregistry of the "Session
Field Parameters sub-registry under http://www.iana.org/assignments/ Initiation Protocol (SIP) Parameters" registry
sip-parameters. <https://www.iana.org/assignments/sip-parameters>, per the guidelines
in [RFC3968]:
Header Field: Reason Header Field: Reason
Parameter Name: location Parameter Name: location
Predefined Values: yes Predefined Values: Yes
Reference: RFCXXXX
Note to RFC Editor: Please replace RFC XXXX with the RFC number of
this specification.
9. Acknowledgments
Thanks to Michael Kreipl, Thoams Belling, Marianne Mohali, Peter Reference: RFC 8606
Daws, Paul Kyzivat, Dale Worley, Yehoshua Gev, Keith Drage for the
comments and review.
10. Normative References 9. Normative References
[Q.850] INTERNATIONAL TELECOMMUNICATION UNION, "Usage of cause and [Q.850] ITU-T, "Usage of cause and location in the Digital
location in the Digital Subscriber Signalling System No. 1 Subscriber Signalling System No. 1 and the Signalling
and the Signalling System No. 7 ISDN User Part", Q 850, System No. 7 ISDN user part", Recommendation ITU-T Q.850,
May 1998. October 2018, <https://www.itu.int/rec/T-REC-Q.850>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
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>.
[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>.
skipping to change at page 7, line 25 skipping to change at page 7, line 19
[RFC6432] Jesske, R. and L. Liess, "Carrying Q.850 Codes in Reason [RFC6432] Jesske, R. and L. Liess, "Carrying Q.850 Codes in Reason
Header Fields in SIP (Session Initiation Protocol) Header Fields in SIP (Session Initiation Protocol)
Responses", RFC 6432, DOI 10.17487/RFC6432, November 2011, Responses", RFC 6432, DOI 10.17487/RFC6432, November 2011,
<https://www.rfc-editor.org/info/rfc6432>. <https://www.rfc-editor.org/info/rfc6432>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Acknowledgments
Thanks to Michael Kreipl, Thomas Belling, Marianne Mohali, Peter
Daws, Paul Kyzivat, Dale Worley, Yehoshua Gev, and Keith Drage for
the comments and review.
Author's Address Author's Address
Roland Jesske Roland Jesske
Deutsche Telekom Deutsche Telekom
Heinrich-Hertz Str, 3-7 Heinrich-Hertz Str, 3-7
Darmstadt 64295 Darmstadt 64295
Germany Germany
Email: r.jesske@telekom.de Email: r.jesske@telekom.de
URI: www.telekom.de URI: www.telekom.de
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