GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc7549

Internet Engineering Task Force (IETF) C. Holmberg Request for Comments: 7549 J. Holm Category: Standards Track Ericsson ISSN: 2070-1721 R. Jesske

                                                      Deutsche Telekom
                                                              M. Dolly
                                                                  AT&T
                                                              May 2015
         3GPP SIP URI Inter-Operator Traffic Leg Parameter

Abstract

 In 3GPP networks, the signaling path between a calling user and a
 called user can be partitioned into segments, referred to as traffic
 legs.  Each traffic leg may span networks belonging to different
 operators and will have its own characteristics that can be different
 from other traffic legs in the same call.  A traffic leg might be
 associated with multiple SIP dialogs, e.g., in case a Back-to-Back
 User Agent (B2BUA) that modifies the SIP dialog identifier is located
 within the traffic leg.
 This document defines a new SIP URI parameter, 'iotl' (an
 abbreviation for Inter-Operator Traffic Leg).  The parameter can be
 used in a SIP URI to indicate that the entity associated with the
 address, or an entity responsible for the host part of the address,
 represents the end of a specific traffic leg (or multiple traffic
 legs).
 The SIP URI 'iotl' parameter defined in this document has known uses
 in 3GPP networks.  Usage in other networks is also possible.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7549.

Holmberg, et al. Standards Track [Page 1] RFC 7549 3GPP 'iotl' May 2015

Copyright Notice

 Copyright (c) 2015 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Holmberg, et al. Standards Track [Page 2] RFC 7549 3GPP 'iotl' May 2015

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
 2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   6
 3.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .   6
 4.  Traffic Leg Examples  . . . . . . . . . . . . . . . . . . . .   6
   4.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.2.  Originating Roaming Call  . . . . . . . . . . . . . . . .   6
   4.3.  Terminating Roaming Call  . . . . . . . . . . . . . . . .   7
   4.4.  Call from Originating Home to Terminating Home  . . . . .   7
 5.  'iotl' SIP URI Parameter  . . . . . . . . . . . . . . . . . .   7
   5.1.  Usage . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.2.  Parameter Values  . . . . . . . . . . . . . . . . . . . .   8
     5.2.1.  General . . . . . . . . . . . . . . . . . . . . . . .   8
     5.2.2.  homea-homeb . . . . . . . . . . . . . . . . . . . . .   8
     5.2.3.  homeb-visitedb  . . . . . . . . . . . . . . . . . . .   8
     5.2.4.  visiteda-homea  . . . . . . . . . . . . . . . . . . .   9
     5.2.5.  homea-visiteda  . . . . . . . . . . . . . . . . . . .   9
     5.2.6.  visiteda-homeb  . . . . . . . . . . . . . . . . . . .   9
 6.  Syntax  . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   6.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .  10
   6.2.  ABNF  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
 7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
 8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
 9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
   9.2.  Informative References  . . . . . . . . . . . . . . . . .  11
 Appendix A.  3GPP Examples  . . . . . . . . . . . . . . . . . . .  12
   A.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .  12
   A.2.  The UE Registers via P-CSCF . . . . . . . . . . . . . . .  12
   A.3.  Originating IMS Call  . . . . . . . . . . . . . . . . . .  14
   A.4.  Terminating IMS Call  . . . . . . . . . . . . . . . . . .  15
   A.5.  Call between Originating Home and Terminating Home
         Network . . . . . . . . . . . . . . . . . . . . . . . . .  16
 Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  17
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

Holmberg, et al. Standards Track [Page 3] RFC 7549 3GPP 'iotl' May 2015

1. Introduction

 In a 3GPP network, an end-user device can be attached (e.g., using a
 radio access network) to its own operator network (home network)
 [TS.3GPP.24.229] or to another operator's network (visited network)
 [TS.3GPP.24.229].  In the latter case, the user is referred to as a
 roaming user.
 3GPP operator networks are often not connected directly to each
 other.  Instead, there might be intermediate networks, referred to as
 3GPP transit networks, between them.  Such transit networks act on
 the SIP level or the IP level.
 In 3GPP networks, the signaling path between a calling user and a
 called user can be partitioned into segments, referred to as traffic
 legs.  Each traffic leg may span networks belonging to different
 operators and will have its own characteristics that can be different
 from other traffic legs in the same call.  A traffic leg might be
 associated with multiple SIP dialogs, e.g., in case a B2BUA [RFC3261]
 that modifies the SIP dialog identifier is located within the traffic
 leg.
 The traffic leg information can be used by intermediary entities to
 make policy decisions related to, e.g., media anchoring, signaling
 policy, insertion of media functions (e.g., transcoder), and
 charging.
 The figure below shows two users (Alice and Bob) and the different
 type of networks that the signaling might traverse.  The signaling
 path can be divided into multiple traffic legs, and the type of
 traffic legs depends on how the signaling is routed.

Holmberg, et al. Standards Track [Page 4] RFC 7549 3GPP 'iotl' May 2015

 Alice -- ORIG HNW +++++ TRANSIT NW +++++ TERM HNW -- Bob
 Home           +     +                +    +   +    Home
                +     ++++++++++++++++++    +   +
                +                           +   +
                +                           +   +
                +     +++++++++++++++++++++++   +
                +     +              +          +
 Alice -- ORIG VNW +++++ TRANSIT NW ++    TERM VNW -- Bob
 Visited                                           Visited
 ORIG HNW  =     Originating 3GPP Home Network
 TERM HNW  =     Terminating 3GPP Home Network
 ORIG VNW  =     Originating 3GPP Visited Network
 TERM VNW  =     Terminating 3GPP Visited Network
 TRANSIT NW =    3GPP Transit Network
             Figure 1: 3GPP Operator Network Roaming Roles
 In Figure 1, Alice is a user initiating communication with Bob. Also,
 consider the following information:
 Alice is attached to an originating network, which is either the home
 network of Alice or a visited network (in case Alice is roaming).  In
 both cases, any originating service is provided by the home network
 of Alice.
 Bob is attached to a terminating network, which is either the home
 network of Bob or a visited network (in case Bob is roaming).  In
 both cases, any terminating service is provided by the home network
 of Bob.
 A transit network providing transit functions (e.g., translation of
 free phone numbers) may be included between the originating and
 terminating networks and between visited and home networks.
 This document defines a new SIP URI parameter [RFC3261], 'iotl' (an
 abbreviation for Inter-Operator Traffic Leg).  The parameter can be
 used in a SIP URI to indicate that the entity associated with the
 address, or an entity responsible for the host part of the address,
 represents the end of a specific traffic leg (or multiple traffic
 legs).

Holmberg, et al. Standards Track [Page 5] RFC 7549 3GPP 'iotl' May 2015

 This document defines the following 'iotl' parameter values:
 o  homea-homeb
 o  homeb-visitedb
 o  visiteda-homea
 o  homea-visiteda
 o  visiteda-homeb
 SIP entities that do not support the SIP URI 'iotl' parameter will
 simply ignore it, if received, as defined in [RFC3261].

2. Conventions

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].

3. Applicability

 The SIP URI 'iotl' parameter defined in this document has known uses
 in 3GPP networks.  Usage in other networks is also possible.

4. Traffic Leg Examples

4.1. General

 This section describes examples of different types of traffic legs in
 3GPP networks.

4.2. Originating Roaming Call

 In this case, Alice is located in a visited network.  When Alice
 sends the initial SIP INVITE request for a call, one traffic leg
 (referred to as the 'visiteda-homea' traffic leg) represents the
 signaling path between the User Agent (UA) of Alice and the home
 Serving Call Session Control Function (S-CSCF) [TS.3GPP.24.229] of
 Alice.

Holmberg, et al. Standards Track [Page 6] RFC 7549 3GPP 'iotl' May 2015

4.3. Terminating Roaming Call

 In this case, Bob is located in a visited network.  When the home
 S-CSCF of Bob forwards the initial SIP INVITE request for a call
 towards Bob, one traffic leg (referred to as the 'homeb-visitedb'
 traffic leg) represents the signaling path between the home S-CSCF of
 Bob and the UA of Bob.

4.4. Call from Originating Home to Terminating Home

 In this case, the home S-CSCF of Alice forwards the initial SIP
 INVITE request towards the home S-CSCF of Bob. The signaling path
 between the S-CSCFs represents one traffic leg (referred to as the
 'homea-homeb' traffic leg).

5. 'iotl' SIP URI Parameter

5.1. Usage

 As specified in [RFC3261], when a SIP entity inserts a SIP URI in an
 initial request for a dialog, or in a stand-alone request, the SIP
 URI will be used to route the request to another SIP entity,
 addressed by the SIP URI, or to a SIP entity responsible for the host
 part of the SIP URI (e.g., a SIP registrar).  If such an entity
 represents the end of one or more traffic legs, the SIP entity
 inserting the SIP URI can add a SIP URI 'iotl' parameter to the SIP
 URI to indicate the type(s) of traffic leg.  Each parameter value
 indicates a type of traffic leg.
 For routing of an initial SIP request for a dialog, or a stand-alone
 SIP request, a SIP entity can add the 'iotl' parameter to (a) the SIP
 URI of the Request-URI [RFC3261] or (b) the SIP URI of a Route header
 field [RFC3261] of the SIP request.  SIP entities can add the 'iotl'
 parameter to the SIP URI of a Path header field [RFC3327] or a
 Service-Route header field [RFC3608] in order for the parameter to
 later occur in a Route header field.
 When a SIP entity receives an initial request for a dialog or a
 stand-alone request, which contains one or more SIP URI 'iotl'
 parameters, it identifies the type of traffic leg in the following
 way:
 o  if the SIP request contains a single Route header field containing
    a SIP URI with an 'iotl' parameter, that parameter identifies the
    type of traffic leg;

Holmberg, et al. Standards Track [Page 7] RFC 7549 3GPP 'iotl' May 2015

 o  if the SIP request contains multiple Route header fields
    containing a SIP URI with an 'iotl' parameter, the 'iotl'
    parameter associated with the SIP URI of the topmost Route header
    field (or, if the SIP URI of the topmost Route header field does
    not contain an 'iotl' parameter, the SIP URI of the Route header
    field closest to the topmost) identifies the type of traffic leg;
    or
 o  if a SIP request contains an 'iotl' parameter only in the Request-
    URI SIP URI, the 'iotl' parameter identifies the type of traffic
    leg.
 During SIP registration [RFC3261], entities can add the 'iotl'
 parameter to the SIP URI of a Path or Service-Route header field if
 the entity is aware that the SIP URI will be used to indicate the end
 of a specific traffic leg for initial requests for dialogs or stand-
 alone requests sent on the registration path.
 As defined in [RFC3261], a SIP proxy must not modify or remove URI
 parameters from SIP URIs associated with other entities.  This also
 applies to the 'iotl' parameter.

5.2. Parameter Values

5.2.1. General

 This section describes the SIP URI 'iotl' parameter values defined in
 this specification.
 Note that, when a request is routed between different networks, the
 request might traverse one or more IBCFs (Interconnection Border
 Control Functions) acting as network border entities.

5.2.2. homea-homeb

 This value indicates that a SIP entity responsible for the host part
 of the SIP URI associated with the parameter represents the end of a
 traffic leg between the home network (originating) of the calling
 user and the home network (terminating) of the called user.
 In 3GPP, this traffic leg is between two S-CSCFs.

5.2.3. homeb-visitedb

 This value indicates that the SIP entity addressed by the SIP URI
 associated with the parameter represents the end of a traffic leg
 between the home network (terminating) of the called user and the
 visited network (terminating) in which the called user is located.

Holmberg, et al. Standards Track [Page 8] RFC 7549 3GPP 'iotl' May 2015

 In 3GPP, this traffic leg is between the home S-CSCF and the User
 Equipment (UE) of the called user or between the Service
 Centralization and Continuity Application Server (SCC AS) in the home
 network of the called user and Access Transfer Control Function
 (ATCF) in the visited network of the called user.

5.2.4. visiteda-homea

 This value indicates that a SIP entity responsible for the host part
 of the SIP URI associated with the parameter represents the end of a
 traffic leg between the visited network (originating) in which the
 calling user is located and the home network (originating) of the
 calling user.
 In 3GPP, this traffic leg is between the UE and the home S-CSCF of
 the calling user or between the Proxy Call Session Control Function
 (P-CSCF) in the visited network, serving the calling user and the
 home S-CSCF of the calling user.

5.2.5. homea-visiteda

 This value indicates that the SIP entity addressed by the SIP URI
 associated with the parameter represents the end of a traffic leg
 between the home network (originating) and the visited network
 (originating) in which the calling user is located.
 In 3GPP, this traffic leg is between the home S-CSCF of the calling
 user and the Transit and Roaming Function (TRF) [TS.3GPP.24.229]
 serving the calling user and exists in scenarios where the home
 S-CSCF of the calling user forwards a request back to the visited
 network where the UE of the calling user is located.  An example of
 this is when the Roaming Architecture for Voice over IMS with Local
 Breakout (RAVEL) [TS.3GPP.24.229] feature is enabled.

5.2.6. visiteda-homeb

 This value indicates that a SIP entity responsible for the host part
 of the SIP URI associated with the parameter represents the end of a
 traffic leg between the visited network (originating) of the calling
 user and the home network (terminating) of the called user.
 In 3GPP, this traffic leg is between the TRF [TS.3GPP.24.229] serving
 the calling user and the home S-CSCF of the called user and exists in
 scenarios where a request is forwarded from the visited network where
 the calling user is located directly to the home S-CSCF of the called
 user.  An example of this is when the RAVEL [TS.3GPP.24.229] feature
 is enabled.

Holmberg, et al. Standards Track [Page 9] RFC 7549 3GPP 'iotl' May 2015

6. Syntax

6.1. General

 This section defines the ABNF for the 'iotl' SIP URI parameter.  The
 ABNF defined in this specification is conformant to RFC 5234
 [RFC5234].
 This specification does not create an IANA registry for 'iotl'
 parameter values.  A registry should be considered if new parameter
 values are defined in the future.

6.2. ABNF

 The ABNF [RFC5234] grammar for this SIP URI parameter is:
 uri-parameter =/ iotl-param
 iotl-param    = iotl-tag "=" iotl-value ["." iotl-value]
 iotl-tag      = "iotl"
 iotl-value    = "homea-homeb" / "homeb-visitedb" / "visiteda-homea"
                  / "homea-visiteda" / "visiteda-homeb" / other-iotl
 other-iotl    = 1*iotl-char
 iotl-char     = alphanum / "-"
 ;; alphanum defined in RFC 3261

7. Security Considerations

 The information in the 'iotl' parameter is used for making policy
 decisions.  Such policies can be related to charging and triggering
 of services.  In order to prevent abuse, which could cause user
 billing or service failure, the parameter SHOULD only be used for
 making policy decisions based on the role by nodes within the same
 trust domain [RFC3325], and network boundary entities MUST NOT
 forward information received from untrusted entities.  In addition,
 an agreement MUST exist between the operators for usage of the
 roaming role information.
 General security considerations for SIP are defined in [RFC3261]

8. IANA Considerations

 Per this specification, IANA has added one new value to the "SIP/SIPS
 URI Parameters" registry as defined in [RFC3969].
       Parameter Name  Predefined Values  Reference
       ____________________________________________
                 iotl      Yes            RFC 7549

Holmberg, et al. Standards Track [Page 10] RFC 7549 3GPP 'iotl' May 2015

9. References

9.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
            A., Peterson, J., Sparks, R., Handley, M., and E.
            Schooler, "SIP: Session Initiation Protocol", RFC 3261,
            DOI 10.17487/RFC3261, June 2002,
            <http://www.rfc-editor.org/info/rfc3261>.
 [RFC3327]  Willis, D. and B. Hoeneisen, "Session Initiation Protocol
            (SIP) Extension Header Field for Registering Non-Adjacent
            Contacts", RFC 3327, DOI 10.17487/RFC3327, December 2002,
            <http://www.rfc-editor.org/info/rfc3327>.
 [RFC3608]  Willis, D. and B. Hoeneisen, "Session Initiation Protocol
            (SIP) Extension Header Field for Service Route Discovery
            During Registration", RFC 3608, DOI 10.17487/RFC3608,
            October 2003, <http://www.rfc-editor.org/info/rfc3608>.
 [RFC3969]  Camarillo, G., "The Internet Assigned Number Authority
            (IANA) Uniform Resource Identifier (URI) Parameter
            Registry for the Session Initiation Protocol (SIP)", BCP
            99, RFC 3969, DOI 10.17487/RFC3969, December 2004,
            <http://www.rfc-editor.org/info/rfc3969>.
 [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
            Specifications: ABNF", STD 68, RFC 5234,
            DOI 10.17487/RFC5234, January 2008,
            <http://www.rfc-editor.org/info/rfc5234>.
 [TS.3GPP.24.229]
            3GPP, "Vocabulary for 3GPP Specifications", 3GPP TS 24.229
            12.6.0, September 2014.

9.2. Informative References

 [RFC3325]  Jennings, C., Peterson, J., and M. Watson, "Private
            Extensions to the Session Initiation Protocol (SIP) for
            Asserted Identity within Trusted Networks", RFC 3325,
            DOI 10.17487/RFC3325, November 2002,
            <http://www.rfc-editor.org/info/rfc3325>.

Holmberg, et al. Standards Track [Page 11] RFC 7549 3GPP 'iotl' May 2015

Appendix A. 3GPP Examples

A.1. General

 This section contains example call flows based on 3GPP usage of the
 SIP URI 'iotl' parameter.

A.2. The UE Registers via P-CSCF

 The Visited Proxy (P-CSCF) adds the 'iotl' value 'homeb-visitedb' to
 the Path header field of the REGISTER request to be used for
 terminating routing towards Alice.  The Home Proxy (S-CSCF) adds the
 'iotl' value 'visiteda-homea' to the Service-Route header field to be
 used for originating initial/stand-alone requests from Alice.
           Visited Proxy    Visited Proxy      Home Proxy   Home Proxy

Alice's . . . . P-CSCF . . . . . IBCF-V . . . . . IBCF-H . . . . S-CSCF

|                |                |                |                |
|   REGISTER F1  |                |                |                |
|--------------->|   REGISTER F2  |                |                |
|                |--------------->|   REGISTER F3  |                |
|                |                |--------------->|  REGISTER F4   |
|                |                |                |--------------->|
|                |                |                |                |
|                |                |                |  200 (OK) F5   |
|                |                |                |<---------------|
|                |                |  200 (OK) F6   |                |
|                |                |<---------------|                |
|                |  200 (OK) F7   |                |                |
|                |<---------------|                |                |
|  200 (OK) F8   |                |                |                |
|<---------------|                |                |                |
 F1 REGISTER Alice -> P-CSCF
 REGISTER sip:registrar.home1.net SIP/2.0
 F2 REGISTER P-CSCF -> IBCF-V
 REGISTER sip:registrar.home1.net SIP/2.0
 Path: <p-cscf URI;iotl=homeb-visitedb>
 F3 REGISTER IBCF-V -> IBCF-H
 REGISTER sip:registrar.home1.net SIP/2.0
 Path: <p-cscf URI;iotl=homeb-visitedb>
 F4 REGISTER IBCF-H -> S-CSCF
 REGISTER sip:registrar.home1.net SIP/2.0
 Path: <p-cscf URI;iotl=homeb-visitedb>

Holmberg, et al. Standards Track [Page 12] RFC 7549 3GPP 'iotl' May 2015

 F5 200 OK S-CSCF -> IBCF-H
 200 OK
 Path: <p-cscf URI;iotl=homeb-visitedb>
 Service-Route: <s-cscf URI;iotl=visiteda-homea>
 F6 200 OK IBCF-H -> IBCF-V
 200 OK
 Path: <p-cscf URI;iotl=homeb-visitedb>
 Service-Route: <s-cscf URI;iotl=visiteda-homea>
 F7 200 OK IBCF-V -> P-CSCF
 200 OK
 Path: <p-cscf URI;iotl=homeb-visitedb>
 Service-Route: <s-cscf URI;iotl=visiteda-homea>
 F8 200 OK P-CSCF -> Alice
 200 OK
 Path: <p-cscf URI;iotl=homeb-visitedb>
 Service-Route: <s-cscf URI;iotl=visiteda-homea>
                 Figure 2: The UE Registers via P-CSCF

Holmberg, et al. Standards Track [Page 13] RFC 7549 3GPP 'iotl' May 2015

A.3. Originating IMS Call

 In the originating INVITE request from Alice, the 'iotl' value
 'visiteda-homea', received in the Service-Route header field during
 registration, is added to the Route header field representing the
 Home Proxy (S-CSCF) to indicate the traffic leg type between the
 Visited Proxy (P-CSCF) and the Home Proxy (S-CSCF).
           Visited Proxy    Visited Proxy      Home Proxy   Home Proxy

Alice's . . . . P-CSCF . . . . . IBCF-V . . . . . IBCF-H . . . . S-CSCF

|                |                |                |                |
|   INVITE F1    |                |                |                |
|--------------->|   INVITE F2    |                |                |
|                |--------------->|   INVITE F3    |                |
|                |                |--------------->|   INVITE F4    |
|                |                |                |--------------->|
|                |                |                |                |
|                |                |                |    180   F5    |
|                |                |    180   F6    |<---------------|
|                |    180   F7    |<---------------|                |
|    180   F8    |<---------------|                |                |
|<---------------|                |                |                |
|                |                |                |                |
 F1 INVITE Alice -> P-CSCF
 INVITE sip:Bob@homeb.net SIP/2.0
 Route: <p-cscf URI>,<s-cscf URI;iotl=visiteda-homea>
 F2 INVITE P-CSCF -> IBCF-V
 INVITE sip:Bob@homeb.net SIP/2.0
 Route: <ibcf-v URI>,<s-cscf URI;iotl=visiteda-homea>
 F3 INVITE IBCF-V -> IBCF-H
 INVITE sip:Bob@homeb.net SIP/2.0
 Route: <ibcf-h URI>,<s-cscf URI;iotl=visiteda-homea>
 F4 INVITE IBCF-H -> S-CSCF
 INVITE sip:Bob@homeb.net SIP/2.0
 Route: <s-cscf URI;iotl=visiteda-homea>
       Figure 3: Originating IP Multimedia Subsystem (IMS) Call

Holmberg, et al. Standards Track [Page 14] RFC 7549 3GPP 'iotl' May 2015

A.4. Terminating IMS Call

 In the terminating INVITE request towards Alice, the 'iotl' value
 'homeb-visitedb' provided to the Home Proxy (S-CSCF) during
 registration is added to the Route header field representing the
 Visited Proxy (P-CSCF) to indicate the traffic leg type between the
 Home Proxy (S-CSCF) and the Visited Proxy (P-CSCF).

Home Proxy Home Proxy Visited Proxy Visited Proxy S-CSCF . . . . IBCF-H . . . . . IBCF-V . . . . . P-CSCF . . . . . Bob

|                |                |                |                |
|   INVITE F1    |                |                |                |
|--------------->|   INVITE F2    |                |                |
|                |--------------->|   INVITE F3    |                |
|                |                |--------------->|   INVITE F4    |
|                |                |                |--------------->|
|                |                |                |                |
|                |                |                |    180   F5    |
|                |                |    180   F6    |<---------------|
|                |    180   F7    |<---------------|                |
|    180   F8    |<---------------|                |                |
|<---------------|                |                |                |
|                |                |                |                |
 F1 INVITE S-CSCF -> IBCF-H
 INVITE sip:Bob@visitedb.net SIP/2.0
 Route: <ibcf-h URI>,<p-cscf-v URI;iotl=homeb-visitedb
 F2 INVITE IBCF-H -> IBCF-V
 INVITE sip:Bob@visitedb.net SIP/2.0
 Route: <ibcf-v URI>,<p-cscf-v URI;iotl=homeb-visitedb
 F3 INVITE IBCF-V -> P-CSCF
 INVITE sip:Bob@visitedb.net SIP/2.0
 Route: <p-cscf-v URI;iotl=homeb-visitedb
 F4 INVITE P-CSCF -> Bob
 INVITE sip:Bob@visitedb.net SIP/2.0
                    Figure 4: Terminating IMS Call

Holmberg, et al. Standards Track [Page 15] RFC 7549 3GPP 'iotl' May 2015

A.5. Call between Originating Home and Terminating Home Network

 The S-CSCF of the originating home network adds the 'iotl' value
 'homea-homeb' in the Request-URI of the INVITE, sent towards the
 S-CSCF of the terminating network to indicate the traffic leg type
 between the S-CSCFs.

Home-A Proxy Home-A Proxy Home-B Proxy Home-B Proxy Home-B Proxy S-CSCF-A . . . . IBCF-A . . . . .IBCF-B . . . . .I-CSCF-B . . .S-CSCF-B

|                |                |                |                |
|   INVITE F1    |                |                |                |
|--------------->|   INVITE F2    |                |                |
|                |--------------->|   INVITE F3    |                |
|                |                |--------------->|   INVITE F4    |
|                |                |                |--------------->|
|                |                |                |                |
|                |                |                |    180   F5    |
|                |                |    180   F6    |<---------------|
|                |    180   F7    |<---------------|                |
|    180   F8    |<---------------|                |                |
|<---------------|                |                |                |
|                |                |                |                |
 F1 INVITE S-CSCF-A -> IBCF-A
 INVITE sip:Bob@visitedb.net;iotl=homea-homeb SIP/2.0
 F2 INVITE IBCF-a -> IBCF-B
 INVITE sip:Bob@visitedb.net;iotl=homea-homeb SIP/2.0
 F3 INVITE IBCF-B -> I-CSCF-B
 INVITE sip:Bob@visitedb.net;iotl=homea-homeb SIP/2.0
 F4 INVITE I-CSCF-B -> S-CSCF-B
 INVITE sip:Bob@visitedb.net;iotl=homea-homeb SIP/2.0
 Figure 5: Call between Originating Home and Terminating Home Network

Holmberg, et al. Standards Track [Page 16] RFC 7549 3GPP 'iotl' May 2015

Acknowledgements

 The authors wish to thank everyone in the 3GPP community that gave
 comments on the initial version of this document and contributed with
 comments and suggestions during the work.  A special thanks to Paul
 Kyziwat, Dale Worley, and Michael Hammer.  Robert Sparks performed
 the Gen-ART review of the document.

Authors' Addresses

 Christer Holmberg
 Ericsson
 Hirsalantie 11
 Jorvas  02420
 Finland
 EMail: christer.holmberg@ericsson.com
 Jan Holm
 Ericsson
 Kistavagen 25
 Stockholm16480
 Sweden
 EMail: jan.holm@ericsson.com
 Roland Jesske
 Deutsche Telekom
 Heinrich-Hertz-Strasse 3-7
 Darmstadt  64307
 Germany
 Phone: +4961515812766
 EMail: r.jesske@telekom.de
 Martin Dolly
 AT&T
 718 Clairmore Ave
 Lanoka Harbor  08734
 United States
 EMail: md3135@att.com

Holmberg, et al. Standards Track [Page 17]

/data/webs/external/dokuwiki/data/pages/rfc/rfc7549.txt · Last modified: 2015/05/20 00:48 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki