Internet DRAFT - draft-drage-sipping-rfc3455bis
draft-drage-sipping-rfc3455bis
Network Working Group R. Jesske
Internet-Draft Deutsche Telekom
Obsoletes: 3455 (if approved) K. Drage
Intended status: Informational Alcatel-Lucent
Expires: October 27, 2014 C. Holmberg
Ericsson
April 25, 2014
Private Header (P-Header) Extensions to the Session Initiation Protocol
(SIP) for the 3rd-Generation Partnership Project (3GPP)
draft-drage-sipping-rfc3455bis-14
Abstract
This document describes a set of private Session Initiation Protocol
(SIP) header fields (P-headers) used by the 3rd-Generation
Partnership Project (3GPP), along with their applicability, which is
limited to particular environments. The P-header fields are for a
variety of purposes within the networks that the partners use,
including charging and information about the networks a call
traverses. This document obsoletes RFC3455.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 27, 2014.
Copyright Notice
Copyright (c) 2014 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
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Table of Contents
1. Overall Applicability . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. SIP Private Header Fields . . . . . . . . . . . . . . . . . . 4
4.1. The P-Associated-URI header field . . . . . . . . . . . . 4
4.1.1. Applicability statement for the P-Associated-URI
header field . . . . . . . . . . . . . . . . . . . . 5
4.1.2. Usage of the P-Associated-URI header field . . . . . 5
4.2. The P-Called-Party-ID header field . . . . . . . . . . . 6
4.2.1. Applicability statement for the P-Called-Party-ID
header field . . . . . . . . . . . . . . . . . . . . 10
4.2.2. Usage of the P-Called-Party-ID header field . . . . . 11
4.3. The P-Visited-Network-ID header field . . . . . . . . . . 12
4.3.1. Applicability statement for the P-Visited-Network-ID
header field . . . . . . . . . . . . . . . . . . . . 12
4.3.2. Usage of the P-Visited-Network-ID header field . . . 13
4.4. The P-Access-Network-Info header field . . . . . . . . . 17
4.4.1. Applicability statement for the P-Access-Network-Info
header field . . . . . . . . . . . . . . . . . . . . 18
4.4.2. Usage of the P-Access-Network-Info header . . . . . . 18
4.5. The P-Charging-Function-Addresses header field . . . . . 19
4.5.1. Applicability statement for the P-Charging-Function-
Addresses header field . . . . . . . . . . . . . . . 20
4.5.2. Usage of the P-Charging-Function-Addresses header
field . . . . . . . . . . . . . . . . . . . . . . . . 21
4.6. The P-Charging-Vector header . . . . . . . . . . . . . . 23
4.6.1. Applicability Statement for the P-Charging-Vector
header field . . . . . . . . . . . . . . . . . . . . 25
4.6.2. Usage of the P-Charging-Vector header field . . . . . 25
4.6.3. Usage of the transit-ioi . . . . . . . . . . . . . . 27
4.6.4. Usage of the related-icid . . . . . . . . . . . . . . 28
5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 28
5.1. P-Associated-URI header syntax . . . . . . . . . . . . . 29
5.2. P-Called-Party-ID header syntax . . . . . . . . . . . . . 29
5.3. P-Visited-Network-ID header syntax . . . . . . . . . . . 29
5.4. P-Access-Network-Info header syntax . . . . . . . . . . . 29
5.5. P-Charging-Function-Addresses header field syntax . . . . 31
5.6. P-Charging-Vector header syntax . . . . . . . . . . . . . 31
5.7. New headers . . . . . . . . . . . . . . . . . . . . . . . 33
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6. Security Considerations . . . . . . . . . . . . . . . . . . . 33
6.1. P-Associated-URI . . . . . . . . . . . . . . . . . . . . 33
6.2. P-Called-Party-ID . . . . . . . . . . . . . . . . . . . . 34
6.3. P-Visited-Network-ID . . . . . . . . . . . . . . . . . . 34
6.4. P-Access-Network-Info . . . . . . . . . . . . . . . . . . 34
6.5. P-Charging-Function-Addresses . . . . . . . . . . . . . . 36
6.6. P-Charging-Vector . . . . . . . . . . . . . . . . . . . . 36
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
8. Contributors and Acknowledgements . . . . . . . . . . . . . . 37
9. Appendix: Changes from RFC 3455 . . . . . . . . . . . . . . . 38
10. Appendix: Summary of changes between different versions . . . 40
10.1. Changes between RFC 3455 and -00 . . . . . . . . . . . . 40
10.2. Changes between -00 and -01 . . . . . . . . . . . . . . 41
10.3. Changes between -01 and -02 . . . . . . . . . . . . . . 42
10.4. Changes between -02 and -03 . . . . . . . . . . . . . . 42
10.5. Changes between -03 and -04 . . . . . . . . . . . . . . 42
10.6. Changes between -04 and -05 . . . . . . . . . . . . . . 43
10.7. Changes between -05 and -06 . . . . . . . . . . . . . . 43
10.8. Changes between -06 and -07 . . . . . . . . . . . . . . 43
10.9. Changes between -07 and -08 . . . . . . . . . . . . . . 43
10.10. Changes between -08 and -09 . . . . . . . . . . . . . . 43
10.11. Changes between -09 and -10 . . . . . . . . . . . . . . 43
10.12. Changes between -10 and -11 . . . . . . . . . . . . . . 43
10.13. Changes between -11 and -12 . . . . . . . . . . . . . . 43
10.14. Changes between -12 and -13 . . . . . . . . . . . . . . 44
10.15. Changes between -13 and -14 . . . . . . . . . . . . . . 44
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 44
11.1. Normative References . . . . . . . . . . . . . . . . . . 44
11.2. Informative References . . . . . . . . . . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46
1. 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
apply only to private networks and are not appropriate for use in an
Internet environment. The mechanisms specified here were designed to
satisfy the requirements specified in the 3GPP Release 5 requirements
on SIP [RFC4083] 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.
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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. Overview
The Third Generation Partnership Project (3GPP) uses SIP as the
protocol to establish and tear down multimedia sessions in the
context of its IP Multimedia Subsystem (IMS), as described in the
3GPP TS 23.228 [TS23.228] and 3GPP TS 24.229 [TS24.229]. RFC3455
[RFC3455] defines SIP private header extensions (referred to as
P-headers) which are required by the 3GPP specification. Note that
the requirements for these extensions are documented in
RFC4083[RFC4083]. This document is an update to RFC3455 [RFC3455].
This document updates existing P-header descriptions to address
additional requirements which are needed for 3GPP Release 11. Each
of the P-headers is described in the sections below.
4. SIP Private Header Fields
4.1. The P-Associated-URI header field
This extension allows a registrar to return a set of associated URIs
for a registered SIP address-of-record. We define the P-Associated-
URI header field, used in the 200 (OK) response to a REGISTER
request. The P-Associated-URI header field contains the set of
Associated URIs that are associated with the registered address-of-
record.
In addition to the address-of-record an associated URI is a URI that
the service provider has allocated to a user. A registrar contains
information that allows zero or more URIs to be associated with an
address-of-record. Usually, all these URIs (the address-of-record
and the associated URIs) are allocated for the usage of a particular
user. This extension to SIP allows the UAC to know, upon a
successful authenticated registration, which other URIs, if any, the
service provider has associated with an address-of-record URI.
Note that in standard SIP usage RFC3261 [RFC3261], the registrar does
not register the associated URIs on behalf of the user. Only the
address-of-record which is present in the To header field of the
REGISTER is registered and bound to the contact address. The only
information conveyed is that the registrar is aware of other URIs
that can be used by the same user.
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It may be possible, however, that an application server (or even the
registrar itself) registers any of the associated URIs on behalf of
the user by means of a third party registration. However, this third
party registration is out of the scope of this document. A UAC MUST
NOT assume that the associated URIs are registered.
If a UAC wants to check whether any of the associated URIs is
registered, it can do so by mechanisms specified outside this
document, e.g., the UA MAY send a REGISTER request with the To header
field value set to any of the associated URIs and without a Contact
header field. The 200 (OK) response will include a Contact header
field with the list of address-of-record that have been registered
with contact addresses. If the associated URI is not registered, the
UA MAY register it prior to its utilization.
4.1.1. Applicability statement for the P-Associated-URI header field
The P-Associated-URI header field is applicable in SIP networks where
the SIP provider allows a set of identities that a user can claim (in
header fields like the From header field) in requests that the UA
generates. It furthermore assumes that the provider knows the entire
set of identities that a user can legitimately claim, and that the
user is willing to restrict its claimed identities to that set. This
is in contrast to normal SIP usage, where the From header field is
explicitly an end-user specified field.
4.1.2. Usage of the P-Associated-URI header field
The registrar inserts the P-Associated-URI header field into the 200
(OK) response to a REGISTER request. The header field value is
populated with a list of URIs that are associated to the address-of-
record.
If the registrar supports the P-Associated-URI header field extension
and there is at least one associated URI, then the registrar MUST
insert the P-Associated-URI header field in all the 200 (OK)
responses to a REGISTER request. The absence of a P-Associated-URI
header field indicates that there is no associated URIs for the
registered address-of-record.
4.1.2.1. Procedures at the UA
A UAC may receive a P-Associated-URI header field in the 200 (OK)
response for a REGISTER request. The presence of an header field in
the 200 (OK) response for a REGISTER request implies that the
extension is supported at the registrar.
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The header field value contains a list of one or more associated URIs
to the address-of-record. The UAC MAY use any of the associated URIs
to populate the From header field value, or any other SIP header
field value that provides information of the identity of the calling
party, in a subsequent request.
The UAC MAY check whether the associated URI is registered or not.
This check can be done, e.g., by populating the To header field value
in a REGISTER request sent to the registrar and without a Contact
header field. The 200 (OK) response will include a Contact header
field with the list of address-of-record that have been registered
with contact addresses. As described in SIP [RFC3261], the 200 (OK)
response may contain a Contact header field with zero or more values
(zero meaning the address-of-record is not registered).
4.1.2.2. Procedures at the registrar
A registrar that receives and authorizes a REGISTER request, MAY
associate zero or more URIs with the registered address-of-record.
If the address-of-record under registration does not have any
associated URIs, the P-Associated-URI header field SHALL NOT be
included.
Otherwise, a registrar that supports this specification MUST include
a P-Associated-URI header field in the 200 (OK) response to a
REGISTER request which contains a contact header. The header field
MUST be populated with a comma-separated list of URIs which are
associated to the address-of-record under registration.
4.1.2.3. Procedures at the proxy
This header is not intended to be used by proxies - a proxy does not
add, read, modify or delete the header field, and therefore any proxy
MUST relay this header field unchanged.
4.2. The P-Called-Party-ID header field
A proxy server inserts a P-Called-Party-ID header field, typically in
an INVITE request, en-route to its destination. The header is
populated with the Request-URI received by the proxy in the request.
The UAS identifies which address-of-record, out of several registered
address-of-records, the invitation was sent to (for example, the user
may be simultaneously using one personal SIP URI and one business SIP
URI to receive invitation to sessions). The UAS can use the
information to render different distinctive audiovisual alerting
tones, depending on the URI used to receive the invitation to the
session.
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Users in the 3GPP IP Multimedia Subsystem (IMS) may get one or
several SIP URIs (address-of-record) to identify the user. For
example, a user may get one business SIP URI and one personal SIP
URI. As an example of utilization, the user may make available the
business SIP URI to co-workers and may make available the personal
SIP URI to members of the family.
At a certain point in time, both the business SIP URI and the
personal SIP URI are registered in the SIP registrar, so both URIs
can receive invitations to new sessions. When the user receives an
invitation to join a session, he/she should be aware of which of the
registered SIP URIs this session was sent to.
This requirement is stated in the 3GPP Release 5 requirements on SIP
[RFC4083].
The problem arises during the terminating side of a session
establishment, when the SIP proxy that is serving a UA gets an INVITE
request, and the SIP server retargets the SIP URI which is present in
the Request-URI, and replaces it by the SIP URI published by the user
in the Contact header field of the REGISTER request at registration
time. When the UAS receives the INVITE request it cannot determine
which address-of-record the request was sent to.
One can argue that the To header field conveys the semantics of the
called user, and therefore, this extension to SIP is not needed.
Although the To header field in SIP may convey the called party ID in
most situations, there are two particular cases when the above
assumption is not correct:
1. The session has been forwarded, redirected, etc., by previous SIP
proxies, before arriving to the proxy which is serving the called
user.
2. The UAC builds an INVITE request and the To header field is not
the same as the Request-URI.
The problem of using the To header field is that this field is
populated by the UAC and not modified by proxies in the path. If the
UAC, for any reason, did not populate the To header field with the
address-of-record of the destination user, then the destination user
is not able to distinguish which address-of-record the session was
destined.
Another possible solution to the problem is built upon the
differentiation of the Contact header field value between different
address-of-record at registration time. The UA can differentiate
each address-of-record it registers by assigning a different Contact
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header field value. For example, when the UA registers the address-
of-record sip:id1, the Contact header field value can be sip:id1@ua,
while the registration of the address-of-record sip:id2 can be bound
to the Contact header field value sip:id2@ua.
The solution described above assumes that the UA explicitly registers
each of its address-of-records, and therefore, it has full control
over the contact address values assigned to each registration.
However, if the UA does not have full control of its registered
address-of-records, because of, e.g., a third party registration, the
solution does not work. This may be the case of the 3GPP
registration, where the UA may have previously indicated to the
network, by means outside of SIP, that some other address-of-records
may be automatically registered when the UA registers a particular
address-of-record. The requirement is covered in the 3GPP Release 5
requirements on SIP [RFC4083].
In the next paragraphs we show an example of the problem, in the case
there has been some sort of call forwarding in the session, so that
the UAC is not aware of the intended destination URI in the current
INVITE request.
We assume that a User Agent (UA) is registering to its proxy (P1).
Scenario UA --- P1
F1 Register UA -> P1
REGISTER sip:example.com SIP/2.0
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7
To: sip:user1-business@example.com
From: sip:user1-business@example.com;tag=456248
Call-ID: 843817637684230998sdasdh09
CSeq: 1826 REGISTER
Contact: <sip:user1@192.0.2.4>
The user also registers his personal URI to his/her registrar.
F2 Register UA -> P1
REGISTER sip:example.com SIP/2.0
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashdt8
To: sip:user1-personal@example.com
From: sip:user1-personal@example.com;tag=346249
Call-ID: 2Q3817637684230998sdasdh10
CSeq: 1827 REGISTER
Contact: <sip:user1@192.0.2.4>
Later, the proxy/registrar (P1) receives an INVITE request from
another proxy (P2) destined to the user's business SIP address-of-
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record. We assume that this INVITE request has undergone some sort
of forwarding in the past, and as such, the To header field is not
populated with the SIP URI of the user. In this case we assume that
the session was initially addressed to sip:other-
user@othernetwork.com. The SIP server at othernetwork.com has
forwarded this session to sip:user1-business@example.com
Scenario UA --- P1 --- P2
F3 Invite P2 -> P1
INVITE sip:user1-business@example.com SIP/2.0
Via: SIP/2.0/UDP 192.0.2.20:5060;branch=z9hG4bK03djaoe1
To: sip:other-user@othernetwork.com
From: sip:another-user@anothernetwork.com;tag=938s0
Call-ID: 843817637684230998sdasdh09
CSeq: 101 INVITE
The proxy P1 retargets the user and replaces the Request-URI with the
SIP URI published during registration time in the Contact header
field value.
F4 Invite P1 -> UA
INVITE sip:user1@192.0.2.4 SIP/2.0
Via: SIP/2.0/UDP 192.0.2.10:5060;branch=z9hG4bKg48sh128
Via: SIP/2.0/UDP 192.0.2.20:5060;branch=z9hG4bK03djaoe1
To: sip:other-user@othernetwork.com
From: sip:another-user@anothernetwork.com;tag=938s0
Call-ID: 843817637684230998sdasdh09
CSeq: 101 INVITE
When the UAS receives the INVITE request, it cannot determine whether
it got the session invitation due to his registration of the business
or the personal address-of-record. Neither the UAS nor proxies or
application servers can provide this user a service based on the
destination address-of-record of the session.
We solve this problem by allowing the proxy that is responsible for
the home domain (as defined in SIP) of the user to insert a P-Called-
Party-ID header field that identifies the address-of-record to which
this session is destined.
If this SIP extension is used, the proxy serving the called user will
get the message flow F5, it will populate the P-Called-Party-ID
header field in message flow F6 with the contents of the Request-URI
in F4. This is show in flows F5 and F6 below:
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F5 Invite P2 -> P1
INVITE sip:user1-business@example.com SIP/2.0
Via: SIP/2.0/UDP 192.0.2.20:5060;branch=z9hG4bK03djaoe1
To: sip:other-user@othernetwork.com
From: sip:another-user@anothernetwork.com;tag=938s0
Call-ID: 843817637684230998sdasdh09
CSeq: 101 INVITE
F6 Invite P1 -> UA
INVITE sip:user1@192.0.2.4 SIP/2.0
Via: SIP/2.0/UDP 192.0.2.10:5060;branch=z9hG4bKg48sh128
Via: SIP/2.0/UDP 192.0.2.20:5060;branch=z9hG4bK03djaoe1
To: sip:other-user@othernetwork.com
From: sip:another-user@anothernetwork.com;tag=938s0
Call-ID: 843817637684230998sdasdh09
P-Called-Party-ID: sip:user1-business@example.com
CSeq: 101 INVITE
When the UA receives the INVITE request F6 it can determine the
intended address-of-record of the session, and apply whatever service
is needed for that address-of-record.
4.2.1. Applicability statement for the P-Called-Party-ID header field
The P-Called-Party-ID header field is applicable when the UAS needs
to be aware of the intended address-of-record that was present in the
Request-URI of the request, before the proxy retargets to the contact
address. The UAS may be interested in applying different audiovisual
alerting effects or other filtering services, depending on the
intended destination of the request. It is specially valuable when
the UAS has registered several address-of-records to his registrar,
and therefore, the UAS is not aware of the address-of-record that was
present in the INVITE request when it hit his proxy/registrar, unless
this extension is used.
P-Called-Party-ID header field and the History-Info header field: At
the time RFC3455 [RFC3455]was drafted, the History-Info header field
was a long way from specification; this header has now been specified
and approved in RFC 7044[RFC7044]. It is acknowledged that the
History-Info header field will provide equivalent coverage to that of
the P-Called-Party-ID header field. However the P-Called-Party-ID
header field is used entirely within the 3GPP system and does not
appear to SIP entities outside that of a single 3GPP operator.
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4.2.2. Usage of the P-Called-Party-ID header field
The P-Called-Party-ID header field provides proxies and the UAS with
the address-of-record that was present in the Request-URI of the
request, before a proxy retargets the request. This information is
intended to be used by subsequent proxies in the path or by the UAS.
Typically, a SIP proxy inserts the P-Called-Party-ID header field
prior to retargetting the Request-URI in the SIP request. The header
field value is populated with the contents of the Request-URI, prior
to replacing it with the contact address.
4.2.2.1. Procedures at the UA
A UAC MUST NOT insert a P-Called-Party-ID header field in any SIP
request or response.
A UAS may receive a SIP request that contains a P-Called-Party-ID
header field. The header field will be populated with the address-
of-record received by the proxy in the Request-URI of the request,
prior to its forwarding to the UAS.
The UAS MAY use the value in the P-Called-Party-ID header field to
provide services based on the called party URI, such as, e.g.,
filtering of calls depending on the date and time, distinctive
presentation services, distinctive alerting tones, etc.
4.2.2.2. Procedures at the proxy
A proxy that has access to the contact information of the user, can
insert a P-Called-Party-ID header field in any of the requests
indicated in the Table 1 (Section 5.7). When included, the proxy
MUST populate the header field value with the contents of the
Request-URI present in the SIP request that the proxy received.
It is necessary that the proxy which inserts the P-Called-Party-ID
header field has information about the user, in order to prevent a
wrong delivery of the called party ID. This information may, for
example have been learned through a registration process.
A proxy or application server that receives a request containing a P
-Called-Party-ID header field MAY use the contents of the header
field to provide a service to the user based on the URI of that
header field value.
A SIP proxy MUST NOT insert a P-Called-Party-ID header field in
REGISTER requests.
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4.3. The P-Visited-Network-ID header field
3GPP networks are composed of a collection of so called home
networks, visited networks and subscribers. A particular home
network may have roaming agreements with one or more visited
networks. This has the effect that when a mobile terminal is
roaming, it can use resources provided by the visited network in a
transparent fashion.
One of the conditions for a home network to accept the registration
of a UA roaming to a particular visited network, is the existence of
a roaming agreement between the home and the visited network. There
is a need to indicate to the home network which one is the visited
network that is providing services to the roaming UA.
3GPP user agents always register to the home network. The REGISTER
request is proxied by one or more proxies located in the visited
network towards the home network. For the sake of a simple approach,
it seems sensible that the visited network includes an identification
that is known to the home network. This identification should be
globally unique, and takes the form of a quoted text string or a
token. The home network may use this identification to verify the
existence of a roaming agreement with the visited network, and to
authorize the registration through that visited network.
Note that P-Visited-Network information reveals the location of the
user, to the level of the coverage area of the visited network. For
a national network, for example, P-Visited-Network would reveal that
the user is in the country in question.
4.3.1. Applicability statement for the P-Visited-Network-ID header
field
The P-Visited-Network-ID header field is applicable whenever the
following circumstances are met:
1. There is transitive trust in intermediate proxies between the UA
and the home network proxy via established relationships between
the home network and the visited network, supported by the use of
standard security mechanisms, e.g., IPsec, AKA, or TLS.
2. An endpoint is using resources provided by one or more visited
networks (a network to which the user does not have a direct
business relationship).
3. A proxy that is located in one of the visited networks wants to
be identified at the user's home network.
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4. There is no requirement that every visited network needs to be
identified at the home network. Those networks that want to be
identified make use of this extension. Those networks that do
not want to be identified do nothing.
5. A commonly pre-agreed text string or token identifies the visited
network at the home network.
6. The UAC sends a REGISTER request or dialog-initiating request
(e.g., INVITE request) or a standalone request outside a dialog
(e.g., OPTIONS request) to a proxy in a visited network.
7. The request traverses, en route to its destination, a first proxy
located in the visited network, and a second proxy located in the
home network or its destination is the registrar in the home
network.
8. The registrar or home proxy verifies and authorizes the usage of
resources (e.g., proxies) in the visited network.
The P-Visited-Network-ID header field assumes that there is trust
relationship between a home network and one or more transited visited
networks. It is possible for other proxies between the proxy in the
visited network that inserts the header, and the registrar or the
home proxy, to modify the value of P-Visited-Network-ID header field.
Therefore intermediaries participating in this mechanism MUST apply a
hop-by-hop integrity protection mechanism such as IPsec or other
available mechanisms in order to prevent such attacks.
4.3.2. Usage of the P-Visited-Network-ID header field
The P-Visited-Network-ID header field is used to convey to the
registrar or home proxy in the home network the identifier of a
visited network. The identifier is a text string or token that is
known by both the registrar or the home proxy at the home network and
the proxies in the visited network.
Typically, the home network authorizes the UA to roam to a particular
visited network. This action requires an existing roaming agreement
between the home and the visited network.
While it is possible for a home network to identify one or more
visited networks by inspecting the domain name in the Via header
fields, this approach has a heavy dependency on DNS. It is an option
for a proxy to populate the Via header field with an IP address, for
example, and in the absence of a reverse DNS entry, the IP address
will not convey the desired information.
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Any SIP proxy in the visited network that receives any of the
requests indicated in Table 1 (Section 5.7) MAY insert a P-Visited-
Network-ID header field when it forwards the request. In case a
REGISTER request or other request is traversing different
administrative domains (e.g., different visited networks), a SIP
proxy MAY insert a new P-Visited-Network-ID header field if the
request does not contain a P-Visited-Network-ID header field with the
same network identifier as its own network identifier (e.g., if the
request has traversed other different administrative domains).
Note also that, there is no requirement for this header field value
to be readable in the proxies. Therefore, a first proxy MAY insert
an encrypted header field that only the registrar can decrypt. If
the request traverses a second proxy located in the same
administrative domain as the first proxy, the second proxy may not be
able to read the contents of the P-Visited-Network-ID header field.
In this situation, the second proxy will consider that its visited
network identifier is not already present in the value of the header
field, and therefore, it will insert a new P-Visited-Network-ID
header field value (hopefully with the same identifier that the first
proxy inserted, although perhaps, not encrypted). When the request
arrives at the registrar or proxy in the home network, it will notice
that the header field value is repeated (both the first and the
second proxy inserted it). The decrypted values should be the same,
because both proxies where part of the same administrative domain.
While this situation is not desirable, it does not create any harm at
the registrar or proxy in the home network.
The P-Visited-Network-ID header field is normally used at
registration. However, this extension does not preclude other
usages. For example, a proxy located in a visited network that does
not maintain registration state MAY insert a P-Visited-Network-ID
header field into any standalone request outside a dialog or a
request that creates a dialog. At the time of writing this document,
the only requests that create dialogs are INVITE requests [RFC3261],
SUBSCRIBE requests [RFC6665] and REFER requests [RFC3515].
In order to avoid conflicts with identifiers, especially when the
number of roaming agreements between networks increase, care must be
taken when selecting the value of the P-Visited-Network-ID header
field. The identifier MUST be globally unique to avoid duplications.
Although there are many mechanism to create globally unique
identifiers across networks, one of such as mechanisms is already in
operation, and that is DNS. The P-Visited-Network-ID header field
does not have any connection to DNS, but the values in the header
field can be chosen from the own DNS entry representing the domain
name of the network. This guarantees the uniqueness of the value.
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4.3.2.1. Procedures at the UA
In the context of the network to which the header fields defined in
this document apply, a User Agent has no knowledge of the P-Visited-
Network-ID when sending the REGISTER request. Therefore user agent
clients MUST NOT insert a P-Visited-Network-ID header field in any
SIP message.
4.3.2.2. Procedures at the registrar and proxy
A SIP proxy which is located in a visited network MAY insert a P
-Visited-Network-ID header field in any of the requests indicated in
the Table 1 (Section 5.7). The header field MUST be populated with
the contents of a text string or a token that identifies the
administrative domain of the network where the proxy is operating
towards the user's home network.
A SIP proxy or registrar which is located in the home network can use
the contents of the P-Visited-Network-ID header field as an
identifier of one or more visited networks that the request
traversed. The proxy or registrar in the home network may take local
policy driven actions based on the existence or not of a roaming
agreement between the home and the visited networks. This means, for
instance, authorize the actions of the request based on the contents
of the P-Visited-Network-ID header field.
A SIP proxy which is located in the home network MUST delete this
header field when forwarding the message outside the home network
administrative domain, in order to retain the user's privacy.
A SIP proxy which is located in the home network SHOULD delete this
header field when the home proxy has used the contents of the header
field or the request is routed based on the called partys
identification, even when the request is not forwarded outside the
home network administrative domain.
Note that a received P-Visited-Network-ID from a UA is not allowed
and MUST be deleted when the request is forwarded.
4.3.2.3. Examples of Usage
We present example in the context of the scenario presented in the
following network diagram:
Scenario UA --- P1 --- P2 --- REGISTRAR
This example shows the message sequence for a REGISTER transaction
originating from UA eventually arriving at the REGISTRAR. P1 is an
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outbound proxy in the visited network for UA. In this case P1
inserts the P-Visited-Network-ID header field. P1 then routes the
REGISTER request to REGISTRAR via P2.
Message sequence for REGISTER using P-Visited-Network-ID header
field:
F1 Register UA -> P1
REGISTER sip:example.com SIP/2.0
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7
To: sip:user1-business@example.com
From: sip:user1-business@example.com;tag=456248
Call-ID: 843817637684230998sdasdh09
CSeq: 1826 REGISTER
Contact: <sip:user1@192.0.2.4>
In flow F2, proxy P1 adds its own identifier in a quoted string to
the P-Visited-Network-ID header field.
F2 Register P1 -> P2
REGISTER sip:example.com SIP/2.0
Via: SIP/2.0/UDP p1@visited.net;branch=z9hG4bK203igld
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashd8
To: sip:user1-personal@example.com
From: sip:user1-personal@example.com;tag=346249
Call-ID: 2Q3817637684230998sdasdh10
CSeq: 1826 REGISTER
Contact: <sip:user1@192.0.2.4>
P-Visited-Network-ID: "Visited network number 1"
Finally, in flow F3, proxy P2 decides to insert its own identifier,
derived from its own domain name to the P-Visited-Network-ID header
field.
F3 Register P2 -> REGISTRAR
REGISTER sip:example.com SIP/2.0
Via: SIP/2.0/UDP p2@other.net;branch=z9hG4bK2bndnvk
Via: SIP/2.0/UDP p1@visited.net;branch=z9hG4bK203igld
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashd8
To: sip:user1-personal@example.com
From: sip:user1-personal@example.com;tag=346249
Call-ID: 2Q3817637684230998sdasdh10
CSeq: 1826 REGISTER
Contact: <sip:user1@192.0.2.4>
P-Visited-Network-ID: other.net,"Visited network number 1"
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4.4. The P-Access-Network-Info header field
This section describes the P-Access-Network-Info header field. This
header field is useful in SIP-based networks that also provide layer
2/layer 3 connectivity through different access technologies. SIP
User Agents may use this header field to relay information about the
access technology to proxies that are providing services. The
serving proxy may then use this information to optimize services for
the UA. For example, a 3GPP UA may use this header field to pass
information about the access network such as radio access technology
and radio cell identity to its home service provider.
For the purpose of this extension, we define an access network as the
network providing the layer 2/layer 3 IP connectivity which in turn
provides a user with access to the SIP capabilities and services
provided.
In some cases, the SIP server that provides the user with services
may wish to know information about the type of access network that
the UA is currently using. Some services are more suitable or less
suitable depending on the access type, and some services are of more
value to subscribers if the access network details are known by the
SIP proxy which provides the user with services.
In other cases, the SIP server that provides the user with services
may simply wish to know crude location information in order to
provide certain services to the user. For example, many of the
location based services available in wireless networks today require
the home network to know the identity of the cell the user is being
served by.
Some regulatory requirements exist mandating that for cellular radio
systems, the identity of the cell where an emergency call is
established is made available to the emergency authorities.
The SIP server that provides services to the user may desire to have
knowledge about the access network. This is achieved by defining a
new private SIP extension header field, P-Access-Network-Info header
field. This header field carries information relating to the access
network between the UAC and its serving proxy in the home network.
A proxy providing services based on the P-Access-Network header field
must consider the trust relationship to the UA or outbound proxy
including the P-Access-Network header field.
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4.4.1. Applicability statement for the P-Access-Network-Info header
field
This mechanism is appropriate in environments where SIP services are
dependent on SIP elements knowing details about the IP and lower
layer technologies used by a UA to connect to the SIP network.
Specifically, the extension requires that the UA know the access
technology it is using, and that a proxy desires such information to
provide services. Generally, SIP is built on the "Everything over IP
and IP over everything" principle, where the access technology is not
relevant for the operation of SIP. Since SIP systems generally
should not care or even know about the access technology, this SIP
extension is not for general SIP usage.
The information revealed in the P-Access-Network-Info header field is
potentially very sensitive. Proper protection of this information
depends on the existence of specific business and security
relationships amongst the proxies that will see SIP messages
containing this header field. It also depends on explicit knowledge
of the UA of the existence of those relationships. Therefore, this
mechanism is only suitable in environments where the appropriate
relationships are in place, and the UA has explicit knowledge that
they exist.
4.4.2. Usage of the P-Access-Network-Info header
When a UA generates a SIP request or response which it knows is going
to be securely sent to its SIP proxy that is providing services, the
UA inserts a P-Access-Network-Info header field into field the SIP
message. This header contains information on the access network that
the UA is using to get IP connectivity. The header is typically
ignored by intermediate proxies between the UA and the SIP proxy that
is providing services. The proxy providing services can inspect the
header and make use of the information contained there to provide
appropriate services, depending on the value of the header. Before
proxying the request onwards to a non-trusted administrative network
domain, this proxy strips the header from the message.
Additionally, the first outbound proxy, if in possession of
appropriate information, can also add a P-Access-Network-Info header
field with its own information.
4.4.2.1. UA behavior
A UA that supports this extension and is willing to disclose the
related parameters MAY insert the P-Access-Network-Info header field
in any SIP request or response.
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The UA inserting this information MUST have a trust relationship with
the proxy that is providing services to protect its privacy by
deleting the header before forwarding the message outside of the
proxy's domain. This proxy is typically located in the home network.
In order to avoid the deletion of the header, there MUST also be a
transitive trust in intermediate proxies between the UA and the proxy
that provides the services. This trust is established by business
agreements between the home network and the access network, and
generally supported by the use of standard security mechanisms, e.g.,
IPsec, AKA, and TLS.
4.4.2.2. Proxy behavior
A proxy MUST NOT modify the value of the P-Access-Network-Info header
field.
A proxy in possession of appropriate information about the access
technology MAY insert a P-Access-Network-Info header field with its
own values. An proxy sending towards an untrusted entity MUST remove
any P-Access-Network-Info header field containing a "network-
provided" value.
A proxy which is providing services to the UA, can act upon any
information present in the P-Access-Network-Info header field value,
if is present, to provide a different service depending on the
network or the location through which the UA is accessing the server.
For example, for cellular radio access networks the SIP proxy located
in the home network MAY use the cell ID to provide basic localized
services.
A proxy that provides services to the user is typically located in
the home network, and therefore trusted. It MUST delete the header
when the SIP signaling is forwarded to a SIP server located in a non-
trusted administrative network domain. The SIP server providing
services to the UA uses the access network information which is of no
interest to other proxies located in different administrative
domains.
4.5. The P-Charging-Function-Addresses header field
3GPP has defined a distributed architecture that results in multiple
network entities becoming involved in providing access and services.
There is a need to inform each SIP proxy involved in a transaction
about the common charging functional entities to receive the
generated charging records or charging events.
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The solution provided by 3GPP is to define two types of charging
functional entities: Charging Collection Function (CCF) and Event
Charging Function (ECF). CCF is used for off-line charging (e.g.,
for postpaid account charging). ECF is used for on-line charging
(e.g., for pre-paid account charging). There may be more than a
single instance of CCF and ECF in a network, in order to provide
redundancy in the network. In case there are more than a single
instance of either the CCF or the ECF addresses, implementations
SHOULD attempt sending the charging data to the ECF or CCF address,
starting with the first address of the sequence (if any) in the P
-Charging-Function-Addresses header field. If the first address of
the sequence is not available then the next address (ccf-2 or ecf-2)
MUST be used if available. The CCF and ECF addresses MAY be passed
during the establishment of a dialog or in a standalone transaction.
More detailed information about charging can be found in 3GPP TS
32.240 [TS32.240] and 3GPP TS 32.260 [TS32.260].
We define the SIP private header field P-Charging-Function-Addresses
header field. A proxy MAY include this header field, if not already
present, in either the initial request or response for a dialog, or
in the request and response of a standalone transaction outside a
dialog. When present, only one instance of the header MUST be
present in a particular request or response.
The mechanisms by which a SIP proxy collects the values to populate
the P-Charging-Function-Addresses header field values are outside the
scope of this document. However, as an example, a SIP proxy may have
preconfigured these addresses, or may obtain them from a subscriber
database.
4.5.1. Applicability statement for the P-Charging-Function-Addresses
header field
The P-Charging-Function-Addresses header field is applicable within a
single private administrative domain where coordination of charging
is required, for example, according to the architecture specified in
3GPP TS 32.240 [TS32.240].
The P-Charging-Function-Addresses header field is not included in a
SIP message sent outside of the own administrative domain. The
header is not applicable if the administrative domain does not
provide a charging function.
The P-Charging-Function-Addresses header field is applicable whenever
the following circumstances are met:
1. A UA sends a REGISTER or dialog-initiating request (e.g., INVITE
request) or a standalone transaction request outside a dialog to
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a proxy located in the administrative domain of a private
network.
2. A registrar, proxy or UA that is located in the administrative
domain of the private network wants to generate charging records.
3. A registrar, proxy or UA that is located in the private network
has access to the addresses of the charging function entities for
that network.
4. There are other proxies located in the same administrative domain
of the private network, that generate charging records or
charging events. The proxies want to send, by means outside SIP,
the charging information to the same charging collecting entities
than the first proxy.
4.5.2. Usage of the P-Charging-Function-Addresses header field
A SIP proxy that receives a SIP request MAY insert a P-Charging-
Function-Addresses header field prior to forwarding the request, if
the header was not already present in the SIP request. The header
filed contains one or more parameters that contain the hostnames or
IP addresses of the nodes that are willing to receive charging
information.
A SIP proxy that receives a SIP request that includes a P-Charging-
Function-Addresses header field can use the hostnames or IP addresses
included in the value, as the destination of charging information or
charging events. The means to send those charging information or
events are outside the scope of this document, and usually, do not
use SIP for that purpose.
4.5.2.1. Procedures at the UA
This document does not specify any procedure at the UA located
outside the administrative domain of a private network, with regard
to the P-Charging-Function-Addresses header field. Such UAs need not
understand this header.
However, it might be possible that a UA is located within the
administrative domain of a private network (e.g., a PSTN gateway, or
conference mixer), and it may have access to the addresses of the
charging entities. In this case, a UA MAY insert the P-Charging-
Function-Addresses header field in a SIP request or response when the
next hop for the message is a proxy or UA located in the same
administrative domain. Similarly such a UA MAY use the contents of
the P-Charging-Function-Addresses header field in communicating with
the charging entities.
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4.5.2.2. Procedures at the Proxy
A SIP proxy that supports this extension and receives a request or
response without the P-Charging-Function-Addresses header field MAY
insert a P-Charging-Function-Addresses header field prior to
forwarding the message. The header is populated with a list of the
addresses of one or more charging entities where the proxy should
send charging related information.
If a proxy that supports this extension receives a request or
response with the P-Charging-Function-Addresses header field, it MAY
retrieve the information from the header field to use with
application specific logic, i.e., charging. If the next hop for the
message is within the administrative domain of the proxy, then the
proxy SHOULD include the P-Charging-Function-Addresses header field
in the outbound message. However, if the next hop for the message is
outside the administrative domain of the proxy, then the proxy MUST
remove the P-Charging-Function-Addresses header field.
4.5.2.3. Examples of Usage
We present example in the context of the scenario presented in the
following network diagram:
Scenario UA1 --- P1 --- P2 --- UA2
In the scenario we assume that P1 and P2 belong to the same
administrative domain.
The example below shows the message sequence for an INVITE
transaction originating from UA1 eventually arriving at UA2. P1 is
an outbound proxy for UA1. In this case P1 inserts charging
information. P1 then routes the request via P2 to UA2.
Message sequence for INVITE using P-Charging-Function-Addresses
header field:
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F1 Invite UA1 -> P1
INVITE sip:ua2@home1.net SIP/2.0
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7
To: sip:ua2@home1.net
From: sip:ua1@home1.net;tag=456248
Call-ID: 843817637684230998sdasdh09
CSeq: 18 INVITE
Contact: sip:ua1@192.0.2.4
F2 Invite P1 -> P2
INVITE sip:ua2@home1.net SIP/2.0
Via: SIP/2.0/UDP p1@home1.net:5060;branch=z9hG4bK34ghi7ab04
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7
To: sip:ua2@home1.net
From: sip:ua1@home1.net;tag=456248
Call-ID: 843817637684230998sdasdh09
CSeq: 18 INVITE
Contact: sip:ua1@192.0.2.4
P-Charging-Function-Addresses:
ccf=192.0.8.1; ecf=192.0.8.3,
ccf-2=192.0.8.2; ecf-2=192.0.8.4
Now both P1 and P2 are aware of the IP addresses of the entities that
collect charging record or charging events. Both proxies can send
the charging information to the same entities.
4.6. The P-Charging-Vector header
3GPP has defined a distributed architecture that results in multiple
network entities becoming involved in providing access and services.
Operators need the ability and flexibility to charge for the access
and services as they see fit. This requires coordination among the
network entities (e.g., SIP proxies), which includes correlating
charging records generated from different entities that are related
to the same session.
The correlation information includes, but is not limited to a
globally unique charging identifier that makes easy the billing
effort.
A charging vector is defined as a collection of charging information.
The charging vector MAY be filled in during the establishment of a
dialog or standalone transaction outside a dialog. The information
inside the charging vector MAY be filled in by multiple network
entities (including SIP proxies) and retrieved by multiple network
entities. There are three types of correlation information to be
transferred: the IMS Charging Identity (ICID) value, the address of
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the SIP proxy that creates the ICID value, and the Inter Operator
Identifiers (IOI).
ICID is a charging value that identifies a dialog or a transaction
outside a dialog. It is used to correlate charging records. ICID
MUST be a globally unique value. One way to achieve globally
uniqueness is to generate the ICID using two components: a locally
unique value and the host name or IP address of the SIP proxy that
generated the locally unique value.
The IOI identifies both the originating and terminating networks
involved in a SIP dialog or transaction outside a dialog. There MAY
be an IOI generated from each side of the dialog to identify the
network associated with each side.
Additionally in a multi network environment one or more transit IOI
identifiers MAY be included along the path of the SIP dialog or
transaction outside a dialog. Due to network policy a void value MAY
be included instead of the transit network name. The void value is
used to indicate that a transit network appeared but due to operator
policy the network name is not shown.
Additionally in a multi service provider environment one or more
transit IOI identifiers MAY be included along the path of the SIP
dialog or transaction outside a dialog. Due to service provider
policy a void value MAY be included instead of the transit service
provider. The void value is used to indicate that a transit appeared
but due to service provider policy the service provider name is not
shown.
There is also expected to be access network charging information,
which consists of network specific identifiers for the access level
(e.g., UMTS radio access network or IEEE 802.11b). The details of
the information for each type of network are not described in this
memo.
We define the SIP private header P-Charging-Vector header field. A
proxy MAY include this header, if not already present, in either the
initial request or response for a dialog, or in the request and
response of a standalone transaction outside a dialog. When present
only one instance of the header MUST be present in a particular
request or response.
The mechanisms by which a SIP proxy collects the values to populate
the P-Charging-Vector header field are outside the scope of this
document.
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4.6.1. Applicability Statement for the P-Charging-Vector header field
The P-Charging-Vector header field is applicable within a single
private administrative domain or between different administrative
domains where there is a trust relationship between the domains.
The P-Charging-Vector header field is not included in a SIP message
sent to another network if there is no trust relationship. The
header is not applicable if the administrative domain manages
charging in a way that does not require correlation of records from
multiple network entities (e.g., SIP proxies).
The P-Charging-Vector header field is applicable whenever the
following circumstances are met:
1. A UA sends a REGISTER or dialog-initiating request (e.g., INVITE)
or mid-dialog request (e.g., UPDATE) or a standalone transaction
request outside a dialog to a proxy located in the administrative
domain of a private network.
2. A registrar, proxy or UA that is located in the administrative
domain of the private network wants to generate charging records.
3. A proxy or UA that is located in the administrative domain of the
private network has access to the charging correlation
information for that network.
4. Optionally, a registrar, proxy or UA that is part of a second
administrative domain in another private network, whose SIP
requests and responses are traversed through, en-route to/from
the first private network, wants to generate charging records and
correlate those records with those of the first private network.
This assumes that there is a trust relationship between both
private networks.
4.6.2. Usage of the P-Charging-Vector header field
The P-Charging-Vector header field is used to convey charging related
information, such as the globally unique IMS charging identifier
(ICID) value.
Typically, a SIP proxy that receives a SIP request that does not
contain a P-Charging-Vector header field MAY insert it, with those
parameters that are available at the SIP proxy.
A SIP proxy that receives a SIP request that contains a P-Charging-
Vector header field can use the values, such as the globally unique
ICID, to produce charging records.
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4.6.2.1. Procedures at the UA
This document does not specify any procedure at a UA located outside
the administrative domain of a private network (e.g., PSTN gateway or
conference mixer), with regard to the P-Charging-Vector header field.
UAs need not understand this header.
However, it might be possible that a UA is located within the
administrative domain of a private network (e.g., a PSTN gateway, or
conference mixer), and it may interact with the charging entities.
In this cases, a UA MAY insert the P-Charging-Vector header field in
a SIP request or response when the next hop for the message is a
proxy or UA located in the same administrative domain. Similar such
a UA MAY use the contents of the P-Charging-Vector header field in
communicating with the charging entities.
4.6.2.2. Procedures at the Proxy
A SIP proxy that supports this extension and receives a request or
response without the P-Charging-Vector header field MAY insert a P
-Charging-Vector header field prior to forwarding the message. The
header is populated with one or more parameters, as described in the
syntax, including but not limited to, a globally unique charging
identifier.
If a proxy that supports this extension receives a request or
response with the P-Charging-Vector header field, it MAY retrieve the
information from the header value to use with application specific
logic, i.e., charging. If the next hop for the message is within the
trusted domain, then the proxy SHOULD include the P-Charging-Vector
header field in the outbound message. If the next hop for the
message is outside the trusted domain, then the proxy MAY remove the
P-Charging-Function-Addresses header field.
Per local application specific logic, the proxy MAY modify the
contents of the P-Charging-Vector header field prior to sending the
message.
4.6.2.3. Examples of Usage
We present example in the context of the scenario presented in the
following network diagram:
Scenario UA1 --- P1 --- P2 --- UA2
This example shows the message sequence for an INVITE transaction
originating from UA1 eventually arriving at UA2. P1 is an outbound
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proxy for UA1. In this case P1 inserts charging information. P1
then routes the call via P2 to UA2.
Message sequence for INVITE using P-Charging-Vector header field:
F1 Invite UA1 -> P1
INVITE sip:joe@example.com SIP/2.0
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7
To: sip:joe@example.com
From: sip:ua1@home1.net;tag=456248
Call-ID: 843817637684230998sdasdh09
CSeq: 18 INVITE
Contact: sip:ua1@192.0.2.4
F2 Invite P1 -> P2
INVITE sip:joe@example.com SIP/2.0
Via: SIP/2.0/UDP P1@home1.net:5060;branch=z9hG4bK34ghi7a
Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7
To: sip:joe@example.com
From: sip:ua1@home1.net;tag=456248
Call-ID: 843817637684230998sdasdh09
CSeq: 18 INVITE
Contact: sip:ua1@192.0.2.4
P-Charging-Vector: icid-value=1234bc9876e;
icid-generated-at=192.0.6.8;
orig-ioi=home1.net
4.6.3. Usage of the transit-ioi
The transit-ioi is added to the P-Charging-Vector header field when
traversing transit networks. It is allowed to have multiple transit-
ioi values within one SIP message or response. The values within the
response are independent from the values set up within the request.
The element could be either added by a transit network itself or by
the succeeding network at the entry point where the preceding network
is known. Based on network policy a void value can be used.
Depending on the call scenario, each transit network can add either a
transit network name or a void value. However, it can not be
guaranteed that all the values that are added will appear within the
P-Charging-Vector header field.
Some networks can screen the P-Charging-Vector header field and
delete transit-ioi values, e.g. networks not supporting this value.
There are scenarios where the appearance of the transit-ioi values of
all networks is needed to have a correct end-to-end view.
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The policies of adding, modifying and deletion of transit-ioi values
are out of the scope of this document.
The transit-ioi contains an indexed value which MUST be incremented
with each value added to the P-charging-Vector header field.
A void value has no index. By adding the next value the index has to
be incremented by the number of void entries +1.
4.6.3.1. Procedures at the Proxy
Procedures described within 4.6.2.2 apply. A transit-ioi MAY be
added or modified by a proxy. A deletion of the transit-ioi or a
entry within the tranist-ioi could appear depending on the network
policy and trust rules. This is also valid by replacing the transit-
ioi with a void value.
4.6.4. Usage of the related-icid
4.6.4.1. Procedures at the UA
The UAS acting as a B2BUA MAY add the related-icid into the P
-Charging-Vector header field into SIP request or SIP responses. For
example, the UAS can include the related-icid in a response to an
INVITE request when the received INVITE request creates a new call
leg towards the same remote end. The value of the related-icid is
the icid value of the original dialog towards the remote end.
4.6.4.2. Procedures at the Proxy
Procedures described within 4.6.2.2 apply. A related-icid and
"related-icid-generated-at" MAY be added or modified by a proxy. A
deletion of the elements could appear depending on the network policy
and trust rules.
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 RFC5234
[RFC5234]. Further, several BNF definitions are inherited from SIP
and are not repeated here. Implementors need to be familiar with the
notation and contents of SIP RFC3261 [RFC3261] and RFC5234 [RFC5234]
to understand this document.
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5.1. P-Associated-URI header syntax
The syntax of the P-Associated-URI header field is described as
follows:
P-Associated-URI = "P-Associated-URI" HCOLON
[p-aso-uri-spec]
*(COMMA p-aso-uri-spec)
p-aso-uri-spec = name-addr *(SEMI ai-param)
ai-param = generic-param
5.2. P-Called-Party-ID header syntax
The syntax of the P-Called-Party-ID header field is described as
follows:
P-Called-Party-ID = "P-Called-Party-ID" HCOLON
called-pty-id-spec
called-pty-id-spec = name-addr *(SEMI cpid-param)
cpid-param = generic-param
5.3. P-Visited-Network-ID header syntax
The syntax of the P-Visited-Network-ID header field is described as
follows:
P-Visited-Network-ID = "P-Visited-Network-ID" HCOLON
vnetwork-spec
*(COMMA vnetwork-spec)
vnetwork-spec = (token / quoted-string)
*(SEMI vnetwork-param)
vnetwork-param = generic-param
5.4. P-Access-Network-Info header syntax
The syntax of the P-Access-Network-Info header field is described as
follows:
P-Access-Network-Info = "P-Access-Network-Info" HCOLON
access-net-spec *(COMMA access-net-spec)
access-net-spec = (access-type / access-class)
*(SEMI access-info)
access-type = "IEEE-802.11" / "IEEE-802.11a" /
"IEEE-802.11b" / "IEEE-802.11g" /
"IEEE-802.11n" /
"IEEE-802.3" / "IEEE-802.3a" /
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"IEEE-802.3ab" / "IEEE-802.3ae" /
"IEEE-802.3ak" / "IEEE-802.3ah" /
"IEEE-802.3aq" / "IEEE-802.3an" /
"IEEE-802.3e" / "IEEE-802.3i" /
"IEEE-802.3j" / "IEEE-802.3u" /
"IEEE-802.3y" / "IEEE-802.3z" /
"3GPP-GERAN" /
"3GPP-UTRAN-FDD" / "3GPP-UTRAN-TDD" /
"3GPP-E-UTRAN-FDD" / "3GPP-E-UTRAN-TDD" /
"3GPP2-1X-Femto" / "3GPP2-UMB" /
"3GPP2-1X-HRPD" / "3GPP2-1X" /
"ADSL" / "ADSL2" / "ADSL2+" / "RADSL" /
"SDSL" / "HDSL" / "HDSL2" / "G.SHDSL" /
"VDSL" / "IDSL" /
"DOCSIS" / "GSTN" / "GPON" / " XGPON1" /
"DVB-RCS2" / token
access-class = "3GPP-GERAN" / "3GPP-UTRAN" /
"3GPP-E-UTRAN" / "3GPP-WLAN" /
"3GPP-GAN" / "3GPP-HSPA" /
"3GPP2" / token
access-info = cgi-3gpp / utran-cell-id-3gpp /
dsl-location / i-wlan-node-id /
ci-3gpp2 / eth-location /
ci-3gpp2-femto / fiber-location /
np / gstn-location /local-time-zone /
dvb-rcs2-node-id / extension-access-info
np = "network-provided"
extension-access-info = gen-value
cgi-3gpp = "cgi-3gpp" EQUAL
(token / quoted-string)
utran-cell-id-3gpp = "utran-cell-id-3gpp" EQUAL
(token / quoted-string)
i-wlan-node-id = "i-wlan-node-id" EQUAL
(token / quoted-string)
dsl-location = "dsl-location" EQUAL
(token / quoted-string)
eth-location = "eth-location" EQUAL
(token / quoted-string)
fiber-location = "fiber-location" EQUAL
(token / quoted-string)
ci-3gpp2 = "ci-3gpp2" EQUAL
(token / quoted-string)
ci-3gpp2-femto = "ci-3gpp2-femto" EQUAL
(token / quoted-string)
gstn-location = "gstn-location" EQUAL
(token / quoted-string)
dvb-rcs2-node-id = "dvb-rcs2-node-id" EQUAL
quoted-string
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local-time-zone = "local-time-zone" EQUAL
quoted-string
operator-specific-GI = "operator-specific-GI" EQUAL
(token / quoted-string)
utran-sai-3gpp = "utran-sai-3gpp" EQUAL
(token / quoted-string)
The access-info MAY contain additional information relating to the
access network. The values for "cgi-3gpp", "utran-cell-id-3gpp", "i
-wlan-node-id", "dsl-location" and "ci-3gpp2", "ci-3gpp2-femto" and
"gstn-location" are defined in 3GPP TS 24.229 [TS24.229].
5.5. P-Charging-Function-Addresses header field syntax
The syntax for the P-Charging-Function-Addresses header field is
described as follows:
P-Charging-Addresses = "P-Charging-Function-Addresses" HCOLON
charge-addr-params *(COMMA charge-addr-params)
charge-addr-params = charge-addr-param *(SEMI charge-addr-param)
charge-addr-param = ccf / ecf / ccf-2 /ecf-2 / generic-param
ccf = "ccf" EQUAL gen-value
ecf = "ecf" EQUAL gen-value
ccf-2 = "ccf-2" EQUAL gen-value
ecf-2 = "ecf-2" EQUAL gen-value
The P-Charging-Function-Addresses header field contains one or two
addresses of the ECF (ecf and ecf-2) or CCF (ccf and ccf-2). The
first address of the sequence is ccf or ecf. If the first address of
the sequence is not available then the next address (ccf-2 or ecf-2)
MUST be used if available.
5.6. P-Charging-Vector header syntax
The syntax for the P-Charging-Vector header field is described as
follows:
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P-Charging-Vector = "P-Charging-Vector" HCOLON icid-value
*(SEMI charge-params)
charge-params = icid-gen-addr / orig-ioi / term-ioi /
transit-ioi / related-icid /
related-icid-gen-addr / generic-param
icid-value = "icid-value" EQUAL gen-value
icid-gen-addr = "icid-generated-at" EQUAL host
orig-ioi = "orig-ioi" EQUAL gen-value
term-ioi = "term-ioi" EQUAL gen-value
transit-ioi = "transit-ioi" EQUAL transit-ioi-list
transit-ioi-list = DQUOTE transit-ioi-param *
(COMMA transit-ioi-param) DQUOTE
transit-ioi-param = transit-ioi-indexed-value /
transit-ioi-void-value
transit-ioi-indexed-value = transit-ioi-name "."
transit-ioi-index
transit-ioi-name = ALPHA *(ALPHA / DIGIT)
transit-ioi-index = 1*DIGIT
transit-ioi-void-value = "void"
related-icid = "related-icid" EQUAL gen-value
related-icid-gen-addr = "related-icid-generated-at" EQUAL host
The P-Charging-Vector header field contains icid-value as a mandatory
parameter. The icid-value represents the IMS charging ID, and
contains an identifier used for correlating charging records and
events. The first proxy that receives the request generates this
value.
The icid-gen-addr parameter contains the host name or IP address of
the proxy that generated the icid-value.
The orig-ioi and term-ioi parameters contains originating and
terminating interoperator identifiers. They are used to correlate
charging records between different operators. The originating ioi
represents the network responsible for the charging records in the
originating part of the session or standalone request. Similarly,
the terminating ioi represents the network responsible for the
charging records in the terminating part of the session or standalone
request.
The transit-ioi parameter contain values with each of them
respectively represents a transit interoperator identifier. It is
used to correlate charging records between different networks. The
transit-ioi represents the network responsible for the records in the
transit part of the session or standalone request.
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The related-icid parameter contains the icid-value of a related
charging record when more than one call leg is associated with one
session. This optional parameter is used for correlation of charging
information between two or more call legs related to the same remote
end dialog.
The related-icid-gen-addr parameter contains the host name or IP
address of the proxy that generated the related-icid.
Applications using the P-Charging-Vector header field within their
own applicability are allowed to define generic-param extensions
without further reference to the IETF specification process.
5.7. New headers
The P-Associated-URI header field can appear in SIP REGISTER method
and 2xx resonses. The P-Called-Party-ID header field can appear in
SIP INVITE, OPTIONS, PUBLISH,SUBSCRIBE, MESSAGE methods and all
responses. The P-Visited-Network-ID header field can appear in all
SIP methods except ACK, BYE and CANCEL and all responses. The P
-Access-Network-Info header field can appear in all SIP methods exept
ACK and CANCEL. The P-Charging-Vector header field can appear in all
SIP methods exept CANCEL. The P-Charging-Function-Addresses header
field can appear in all SIP methods exept ACK and CANCEL.
6. Security Considerations
6.1. P-Associated-URI
The information returned in the P-Associated-URI header field is not
viewed as particularly sensitive. Rather, it is simply informational
in nature, providing openness to the UAC with regard to the automatic
association performed by the registrar. If end-to-end protection is
not used at the SIP layer, it is possible for proxies between the
registrar and the UA to modify the contents of the header value.
The lack of encryption, either end-to-end or hop-by-hop, may lead to
leak some privacy regarding the list of authorized identities. For
instance, a user who registers an address-of-record of
sip:user1@example.com may get another SIP URI associated as
sip:first.last@example.com returned in the P-Associated-URI header
field value.
An eavesdropper could possibly collect the list of identities a user
is registered. This can have privacy implications. To mitigate this
problem, this extension SHOULD only be used in a secured environment,
where encryption of SIP messages is provided either end-to-end or
hop-by-hop. And where a trustrelationship equivalent with that
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defined in RFC 3325 [RFC3325]between entities exist. That is, the
privacy of the user relies on the other entities in the session not
disclosing information that they have learned about the user.
While the P-Associated-URI header field value allows the implicit
registration of a bundle of URIs with one REGISTER Message the impact
of security using the P-Associated-URI header field is no higher than
using separate REGISTER messages for each of the URIs.
6.2. P-Called-Party-ID
Due to the nature of the P-Called-Party-ID header field, this header
does not introduce any significant security concern. It is possible
for an attacker to modify the contents of the header. However, this
modification will not cause any harm to the session establishment.
An eavesdropper could possibly collect the list of identities a user
is registered. This can have privacy implications. To mitigate this
problem, this extension SHOULD only be used in a secured environment,
where encryption of SIP messages is provided either end-to-end or
hop-by-hop.
Normally within a 3GPP environment the P-Called-Party-ID is not sent
towards end users but may be exchanged between carriers where other
security mechanisms than SIP encryption are used.
6.3. P-Visited-Network-ID
The P-Visited-Network-ID header field assumes that there is trust
relationship between a home network and one or more transited visited
networks. It is possible for other proxies between the proxy in the
visited network that inserts the header, and the registrar or the
home proxy, to modify the value of P-Visited-Network-ID header field.
Therefore intermediaries participating in this mechanism MUST apply a
hop-by-hop integrity protection mechanism such as IPsec or other
available mechanisms in order to prevent such attacks.
6.4. P-Access-Network-Info
A Trust Domain is formally defined in the Short term requirements for
Network Asserted Identity document[RFC3324]. For the purpose of this
document, we refer to the 3GPP trust domain as the collection of SIP
proxies and application servers that are operated by a 3GPP network
operator and are compliant with the requirements expressed in 3GPP TS
24.229 [TS24.229].
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This extension assumes that the access network is trusted by the UA
(because the UA's home network has a trust relationship with the
access network), as described earlier in this document.
This extension assumes that the information added to the header by
the UAC should be sent only to trusted entities and MUST NOT be used
outside of the trusted administrative network domain.
The SIP proxy that provides services to the user, utilizes the
information contained in this header to provide additional services
and UAs are expected to provide correct information. However, there
are no security problems resulting from a UA inserting incorrect
information. Networks providing services based on the information
carried in the P-Access-Network-Info header field will therefore need
to trust the UA sending the information. A rogue UA sending false
access network information will do no more harm than to restrict the
user from using certain services.
The mechanism provided in this document is designed primarily for
private systems like 3GPP. Most security requirements are met by way
of private standardized solutions.
For instance, 3GPP will use the P-Access-Network-Info header field to
carry relatively sensitive information like the cell ID. Therefore
the information MUST NOT be sent outside of the 3GPP domain.
The UA is aware - if it is a 3GPP UA - that it is operating within a
trusted domain.
The 3GPP UA is aware of whether or not a secure association to the
home network domain for transporting SIP signaling, is currently
available, and as such the sensitive information carried in the P
-Access-Network-Info header field MUST NOT be sent in any initial
unauthenticated and unprotected requests (e.g., REGISTER).
Any UA that is using this extension and is not part of a private
trusted domain should not consider the mechanism as secure and as
such MUST NOT send sensitive information in the P-Access-Network-Info
header field.
Any proxy that is operating in a private trust domain where the P
-Access-Network-Info header field is supported is REQUIRED to delete
the header, if it is present, from any message prior to forwarding it
outside of the trusted domain.
A proxy receiving a message containing the P-Access-Network-Info
header field from a non-trusted entity is not able to guarantee the
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validity of the contents. Thus this content SHOULD be deleted based
on local policy.
6.5. P-Charging-Function-Addresses
It is expected as normal behavior that proxies within a closed
network will modify the values of the P-Charging-Function-Addresses
header field and insert it into a SIP request or response. However,
these proxies that share this information MUST have a trust
relationship.
If an untrusted entity were inserted between trusted entities, it
could potentially substitute a different charging function address.
Therefore, an integrity protection mechanism such as IPsec or other
available mechanisms MUST be applied in order to prevent such
attacks. Since each trusted proxy MAY need to view or modify the
values in the P-Charging-Function-Addresses header field, the
protection should be applied on a hop-by-hop basis.
6.6. P-Charging-Vector
It is expected as normal behavior that proxies within a closed
network will modify the values of the P-Charging-Vector header field
and insert it into a SIP request or response. However, these proxies
that share this information MUST have a trust relationship.
If an untrusted entity were inserted between trusted entities, it
could potentially interfere with the charging correlation mechanism.
Therefore, an integrity protection mechanism such as IPsec or other
available mechanisms MUST be applied in order to prevent such
attacks. Since each trusted proxy MAY need to view or modify the
values in the P-Charging-Vector header field, the protection should
be applied on a hop-by-hop basis.
7. IANA Considerations
This document defines several private SIP extension header fields
(beginning with the prefix "P-" ).
This document obsoletes [RFC3455] but uses the same SIP header field
names. The IANA registry needs to update the references to [RFC3455]
with [RFC XXXX], where XXXX is the RFC number for this document.
The following extensions are registered as private extension header
fields:
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RFC Number: RFC3455
Header Field Name: P-Associated-URI
Compact Form: none
RFC Number: RFC3455
Header Field Name: P-Called-Party-ID
Compact Form: none
RFC Number: RFC3455
Header Field Name: P-Visited-Network-ID
Compact Form: none
RFC Number: RFC3455
Header Field Name: P-Access-Network-Info
Compact Form: none
RFC Number: RFC3455
Header Field Name: P-Charging-Function-Addresses
Compact Form: none
RFC Number: RFC3455
Header Field Name: P-Charging-Vector
Compact Form: none
8. Contributors and Acknowledgements
The authors would like to thank James Yu ans Atle Monrad for their
extensive review, Dean Willis for his expert review and Mary Barnes
for the proto review. The authors would like to acknowledge the
constructive feedback and contributions provided by Peter Leis,
Joergen Axell and Jan Holm
The extensions described in [RFC3455] were originally specified in
several documents. Miguel Garcia-Martin authored the P-Associated-
URI, P-Called-Party-ID, and P-Visited-Network-ID header fields.
Duncan Mills authored the P-Access-Network-Info header. Eric
Henrikson authored the P-Charging-Function-Addresses and P-Charging-
Vector headers. Rohan Mahy assisted in the incorporation of these
extensions into a single document.
The listed authors of [RFC3455]were Miguel Garcia-Martin, Eric
Henrikson and Duncan Mills.
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The [RFC3455] authors thanked Andrew Allen, Gabor Bajko, Gonzalo
Camarillo, Keith Drage, Georg Mayer, Dean Willis, Rohan Mahy,
Jonathan Rosenberg, Ya-Ching Tan and the 3GPP CN1 WG members for
their comments on [RFC3455].
9. Appendix: Changes from RFC 3455
1. Procedures for the P-Associated-URI header field at a proxy.
RFC3455 indicates that it defines no procedures for the P
-Associated-URI header field at a proxy. What is implicitly
meant here is that the proxy does not add, read, modify or
delete the header, and therefore RFC3261 proxy procedures only
apply to the header.
2. P-Called-Party-ID header field and the History-Info header
field: At the time RFC3455 was drafted, the History-Info header
field was a long way from specification; this header has now
been specified and approved in RFC 7044. It is acknowledged
that the History-Info header field will provide equivalent
coverage to that of the P-Called-Party-ID header field. However
the P-Called-Party-ID header field is used entirely within the
3GPP system and does not appear to SIP entities outside that of
a single 3GPP operator.
3. Procedures at the UA for the P-Charging-Function Addresses
header field: The text in section 4.5.2.1 of RFC3455 [3] does
not adequately take into account procedures for UAs located
inside the private network, e.g. as gateways and suchlike which
may play a full part in network charging procedures.
Section 4.5.2.1 is replaced with the following text: "This
document does not specify any procedure at a UA located outside
the administrative domain of a private network, with regard to
the P-Charging-Function-Addresses header field. Such UAs need
not understand this header. However, it might be possible that
a UA is located within the administrative domain of a private
network (e.g., a PSTN gateway, or conference mixer), and it may
have access to the addresses of the charging entities. In this
cases, a UA MAY insert the P-Charging-Function-Addresses header
field in a SIP request or response when the next hop for the
message is a proxy or UA located in the same administrative
domain. Similar such a UA may use the contents of the P
-Charging-Function-Addresses header field in communicating with
the charging entities."
4. The text in section 4.6.2.1 of RFC3455 [3] does not adequately
take into account procedures for UAs located inside the private
network, e.g. as gateways and suchlike which may play a full
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part in network charging procedures. Section 4.6.2.1 is now
replaced with new text. "
5. Recognition of additional values of access technology in the P
-Access-Network-Info header field (Section 5.4): A number of new
access technologies are contemplated in 3GPP, and the reuse of
IMS to support Next Generation Networks (NGN) is also resulting
in new access technologies. Values for access technologies are
defined explicitly in RFC3455 [3] and no IANA procedures are
defined to maintain a separate registry. In particular the new
values: "IEEE 802.11", "IEEE-802.11g", "IEEE-802.11n", "ADSL" /
"ADSL2", "ADSL2+", "RADSL", "SDSL", "HDSL", "HDSL2", "G.SHDSL",
"VDSL", "IDSL", "IEEE-802.3", "IEEE-802.3a", "IEEE-802.3e",
"IEEE-802.3i", "IEEE-802.3j", "IEEE-802.3u", "IEEE-802.3ab",
"IEEE-802.3ae", "IEEE-802.3ak", IEEE-802.3aq", "IEEE-802.3an",
"IEEE-802.3y", "IEEE-802.3z", and "IEEE-802.3y" are defined.
6. Replacement of existing value of access technology in the P
-Access-Network-Info header field (Section 5.4): The value of
"3GPP-CDMA2000" was replaced long ago in 3GPP2 by three new
values: "3GPP2-1X", "3GPP2-1X-HRPD", "3GPP2-UMB". It is not
believed that there was any deployment of the "3GPP-CDMA2000"
value.
7. Network provided P-Access-Network-Info header field: The P
-Access-Network-Info header field may additionally be provided
by proxies within the network. This does not impact the values
provided by a UA, rather the header is repeated. Such values
are identified by the string "network-provided". A special
class of values are defined for use here, as the same
granularity of values may not be possible as for those available
from the UA: "3GPP-GERAN", "3GPP-UTRAN", "3GPP-WLAN", "3GPP-GAN"
and "3GPP-HSPA". Outbound proxies remove and P-Access-Network-
Info header fields containing the "network-provided" value.
8. Definition of additional parameters to the P-Charging-Vector
header field: Section 5.6 of RFC3455 [3] defines the syntax of
the P-Charging-Vector header field. Additional parameters were
considered too application specific for specification in RFC3455
[3], but it was acknowledged that they would exist, and indeed
additional specification of such parameters, relating to
specific access technologies, has occurred in 3GPP. This update
therefore defines that applications using the P-Charging-Vector
header field within their own applicability are allowed to
define generic-param extensions without further reference to the
IETF specification process.
9. PUBLISH method added to table 1.
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10. Referencing: RFC 3427 deleted from references as not used within
the document. Various informative references to work in
progress now replaced with appropriate RFC number. References
to 3GPP TS 32.200 replaced by references to 3GPP TS 32.240
[TS32.240], which is the successor specification. References to
3GPP TS 32.225 replaced by references to 3GPP TS 32.260
[TS32.260], which is the successor specification. Referencing
style changed to symbolic references. Dates have been removed
from all 3GPP references (i.e. latest version applies).
11. Various editorial changes in alignment with style used in RFC
3261 such as placing response code text in parentheses, and
using words "request" and "response" in association with method
names.
10. Appendix: Summary of changes between different versions
NOTE TO RFC EDITOR: PLEASE REMOVE THIS SECTION BEFORE PUBLICATION.
10.1. Changes between RFC 3455 and -00
1. Procedures for the P-Associated-URI header field at a proxy.
RFC3455 indicates that it defines no procedures for the P
-Associated-URI header field at a proxy. What is implicitly
meant here is that the proxy does not add, read, modify or delete
the header, and therefore RFC3261 proxy procedures only apply to
the header.
2. P-Called-Party-ID header field and the History-Info header field:
At the time RFC3455 was drafted, the History-Info header field
was a long way from specification; this header has now been
specified and approved in RFC 7044. It is acknowledged that the
History-Info header field provides equivalent coverage to that of
the P-Called-Party-ID header field.
3. Recognition of additional values of access technology in the P
-Access-Network-Info header field: the new values: "IEEE
802.11e", "IEEE-802.11g" are defined.
4. Procedures at the UA for the P-Charging-Function Addresses header
field: The text in section 4.5.2.1 of RFC3455 [3] does not
adequately take into account procedures for UAs located inside
the private network, e.g. as gateways and suchlike which may play
a full part in network charging procedures. Section 4.5.2.1 was
updated.
5. The text in section 4.6.2.1 of RFC3455 [3] does not adequately
take into account procedures for UAs located inside the private
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network, e.g. as gateways and suchlike which may play a full part
in network charging procedures. Section 4.6.2.1 is replaced with
tnew text.
6. Definition of additional parameters to the P-Charging-Vector
header field: Section 5.6 of RFC3455 [3] defines the syntax of
the P-Charging-Vector header field. Additional parameters were
considered too application specific for specification in RFC3455
[3], but it was acknowledged that they would exist, and indeed
additional specification of such parameters, relating to specific
access technologies, has occurred in 3GPP. This update therefore
defines that applications using the P-Charging-Vector header
field within their own applicability are allowed to define
generic-param extensions without further reference to the IETF
specification process.
10.2. Changes between -00 and -01
1. Document changed to a complete RFC in its own right, specifying
all the new headers originally specified in RFC 3455 in full,
rather than a list of proposed modifications to RFC 3455. Change
due to comments to this effect, and also due to the replacement
of RFC 3325 is also following this approach. Issues from -00
version incorporated into full text.
2. Removal of additional values of access technology in the P
-Access-Network-Info header field: values "IEEE 802.11e" is
removed.
3. Recognition of additional values of access technology in the P
-Access-Network-Info header field: A number of new access
technologies are contemplated in 3GPP, and the reuse of IMS to
support Next Generation Networks (NGN) is also resulting in new
access technologies. Values for access technologies are defined
explicitly in RFC3455 [3] and no IANA procedures are defined to
maintain a separate registry. In particular the new values:
"IEEE 802.11", "IEEE-802.11n", "ADSL" / "ADSL2", "ADSL2+",
"RADSL", "SDSL", "HDSL", "HDSL2", "G.SHDSL", "VDSL", "IDSL",
"IEEE-802.3", "IEEE-802.3a", "IEEE-802.3e", "IEEE-802.3i",
"IEEE-802.3j", "IEEE-802.3u", "IEEE-802.3ab", "IEEE-802.3ae",
"IEEE-802.3ak", IEEE-802.3aq", "IEEE-802.3an", "IEEE-802.3y",
"IEEE-802.3z", and "IEEE-802.3y" are defined.
4. Replacement of existing value of access technology in the P
-Access-Network-Info header field: The value of "3GPP-CDMA2000"
was replaced long ago in 3GPP2 by three new values: "3GPP2-1X",
"3GPP2-1X-HRPD", "3GPP2-UMB". It is not believed that there was
any deployment of the "3GPP-CDMA2000" value.
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5. Network provided P-Access-Network-Info header field: The P
-Access-Network-Info header field may additionally be provided by
proxies within the network. This does not impact the values
provided by a UA, rather the header field is repeated. Such
values are identified by the string "network-provided". A
special class of values are defined for use here, as the same
granularity of values may not be possible as for those available
from the UA: "3GPP-GERAN", "3GPP-UTRAN", "3GPP-WLAN", "3GPP-GAN"
and "3GPP-HSPA".
10.3. Changes between -01 and -02
1. Addition of values ccf-2 and ecf-2. Note that the naming of ccf
and ecf was changed within 3GPP equivalent to cdf (Charging Data
Function) and ocf (Online Charging Function), but nevertheless
this is a documentationissue within 24.229 [TS24.229]).
2. By text description in 4.1.2.1 and 4.1.2.2, P-Associated-URI may
have zero URI. But refer to the syntax description part in 5.1,
it seams the header field would have at least one URI. The new
text reflects that is allowed to have at minimum one associated
uri within the P-Associated-URI.
3. Section 4.1.2.2 generalisation of URI so that not only SIP/SIP
URI's are only allowed. This alings the whole section 4.1.2
where only URI is mentioned.
10.4. Changes between -02 and -03
1. Section 4.6 addition of transit-ioi procedure
2. New Section 4.6.3 addition of transit-ioi procedure
3. Section 5.6 Addition of syntax for transit-ioi and descriptive
text
4. Section 5.4 new Value "IEEE-802.3ah" added
10.5. Changes between -03 and -04
1. Section 5.6, 4.6.4 and 4.6.4.1 related-icid added
2. Editorials in diffrent sections
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10.6. Changes between -04 and -05
1. Correction of exampl in Section 4.5.2.3
2. textual addition in section 4.5 for ccf-2 and ecf-2
3. Correction of ABNF
10.7. Changes between -05 and -06
1. Correction ABNF addition and correction of access types and
access info
10.8. Changes between -06 and -07
1. Made Use of P-Charging-Vector Header optional Section 4.6
2. Section 4.6.1 added explicit the mid-dialog request
10.9. Changes between -07 and -08
1. Comments included from review of James Yu sent via DISPATCH list.
Mainly editorials, wording issues and clarifications on technical
issues. No technical changes or addition of features.
10.10. Changes between -08 and -09
1. Correction of ABNF change UE-time-zone to local-time-zone
2. Comments from Expert review
3. Editorial wrap-up
10.11. Changes between -09 and -10
1. Changes due to reviw on IETF DISPATCH List.
10.12. Changes between -10 and -11
1. Changes due to backwardcompatibility in Section 6.1 and 6.2
10.13. Changes between -11 and -12
1. RFC updates of obsolated drafts
2. ABNF correction
3. correction of nits ect
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10.14. Changes between -12 and -13
1. This RFC obsolates RFC3455
2. correction of FDQN
3. deletion of not used references
10.15. Changes between -13 and -14
1. Section 4.3 text added to reflect the fact that the P-Visited-
Network information reveals the location of the user.
2. Section 4.3.1 hop-by-hop integrity protection requirement added.
3. Update of 3GPP References and TS24.229 [TS24.229] to normative
reference.
4. Section 4.4 text added regarding that the proxy providing
services based on the P-Access-Network header field must consider the
trust relationship.
5. Section 4.4.1 Adding a verb to provide correct grammar.
6. Section 4.3.2.2 rewording Note. To reflect that a UA is not
allowed to set the P-Visited-Network ID.
7. Section 4.6 editorial
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3261] 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.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
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Internet-Draft 3GPP SIP P-Header Extensions April 2014
[TS24.229]
3GPP, "IP multimedia call control protocol based on
Session Initiation Protocol (SIP) and Session Description
Protocol (SDP); Stage 3", 3GPP TS 24.229 12.4.0, March
2014.
11.2. Informative References
[RFC3324] Watson, M., "Short Term Requirements for Network Asserted
Identity", RFC 3324, November 2002.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325,
November 2002.
[RFC3455] Garcia-Martin, M., Henrikson, E., and D. Mills, "Private
Header (P-Header) Extensions to the Session Initiation
Protocol (SIP) for the 3rd-Generation Partnership Project
(3GPP)", RFC 3455, January 2003.
[RFC3515] Sparks, R., "The Session Initiation Protocol (SIP) Refer
Method", RFC 3515, April 2003.
[RFC4083] Garcia-Martin, M., "Input 3rd-Generation Partnership
Project (3GPP) Release 5 Requirements on the Session
Initiation Protocol (SIP)", RFC 4083, May 2005.
[RFC6665] Roach, A., "SIP-Specific Event Notification", RFC 6665,
July 2012.
[RFC7044] Barnes, M., Audet, F., Schubert, S., van Elburg, J., and
C. Holmberg, "An Extension to the Session Initiation
Protocol (SIP) for Request History Information", RFC 7044,
February 2014.
[TS23.228]
3GPP, "P Multimedia Subsystem (IMS); Stage 2", 3GPP TS
23.228 12.4.0, March 2014.
[TS32.240]
3GPP, "Telecommunication management; Charging management;
Charging architecture and principles", 3GPP TS 32.240
12.3.0, March 2013.
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Internet-Draft 3GPP SIP P-Header Extensions April 2014
[TS32.260]
3GPP, "Telecommunication management; Charging management;
IP Multimedia Subsystem (IMS) charging", 3GPP TS 32.260
10.3.0, April 2011.
Authors' Addresses
Roland Jesske
Deutsche Telekom
Heinrich-Hertz-Strasse 3-7
Darmstadt 64307
Germany
Phone: +4961515812766
Email: r.jesske@telekom.de
Keith Drage
Alcatel-Lucent
Quadrant, StoneHill Green, Westlea
Swindon, Wilts
UK
Email: drage@alcatel-lucent.com
Christer Holmberg
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
Email: christer.holmberg@ericsson.com
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