ETSI TS 129 217 V15.1.0 (2019-10)

ETSI TS 129 217 V15.1.0 (2019-10)






TECHNICAL SPECIFICATION
Universal Mobile Telecommunications System (UMTS);
LTE;
Policy and Charging Control (PCC);
Congestion reporting over Np reference point
(3GPP TS 29.217 version 15.1.0 Release 15)

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3GPP TS 29.217 version 15.1.0 Release 15 1 ETSI TS 129 217 V15.1.0 (2019-10)



Reference
RTS/TSGC-0329217vf10
Keywords
LTE,UMTS
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3GPP TS 29.217 version 15.1.0 Release 15 2 ETSI TS 129 217 V15.1.0 (2019-10)
Intellectual Property Rights
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Legal Notice
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities. These shall be
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Modal verbs terminology
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"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

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3GPP TS 29.217 version 15.1.0 Release 15 3 ETSI TS 129 217 V15.1.0 (2019-10)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 7
4 Np reference point . 7
4.1 Overview . 7
4.2 Np reference model . 8
4.3 Functional ele me nts . 8
4.3.1 RCAF . 8
4.3.2 PCRF . 9
4.3.3 H-PCRF . 9
4.3.4 V-PCRF . 9
4.4 Procedures over Np reference point . 9
4.4.1 RUCI Report . 9
4.4.1.1 General . 9
4.4.1.2 Non-aggregated RUCI report . 10
4.4.1.3 Aggregated RUCI report . 10
4.4.2 Reporting Restriction Provisioning . 10
4.4.3 UE mobility between RCAFs . 11
4.4.4 Removal of UE context . 11
4.4.5 Race condition handling . 12
5 Np protocol . 12
5.1 Protocol support . 12
5.2 Initialization, maintenance and termination of connection and session. 12
5.3 Np specific AVPs . 13
5.3.1 General . 13
5.3.2 Aggregated-Congestion-Info AVP . 13
5.3.3 Aggregated-RUCI-Report AVP . 13
5.3.4 Congestion-Level-Definition AVP . 14
5.3.5 Congestion-Level-Range AVP . 14
5.3.6 Congestion-Level-Set-Id AVP . 14
5.3.7 Congestion-Level-Value AVP . 14
5.3.8 Congestion-Location-Id AVP . 15
5.3.9 Conditional-Restriction AVP . 15
5.3.10 eNodeB-Id AVP . 15
5.3.11 IMSI-List AVP . 15
5.3.12 RCAF-Id AVP . 16
5.3.13 Reporting-Restriction AVP . 16
5.3.14 RUCI-Action AVP . 16
5.3.15 Extended-eNodeB-Id AVP . 17
5.4 Np re-used AVPs . 17
5.4.1 General . 17
5.4.2 Use of the Supported-Features AVP on the Np reference point . 18
5.5 Np specific Experimental-Result-Code AVP values . 19
5.5.1 General . 19
5.5.2 Success . 19
5.5.3 Permanent Failures . 19
5.5.4 Transient Failures . 19
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5.6 Np messages . 19
5.6.0 Command-Code Values . 19
5.6.1 Non-Aggregated-RUCI-Report-Request (NRR) command . 20
5.6.2 Non-Aggregated-RUCI-Report-Answer (NRA) command . 20
5.6.3 Aggregated-RUCI-Report-Request (ARR) command . 21
5.6.4 Aggregated-RUCI-Report-Answer (ARA) command . 21
5.6.5 Modify-Uecontext-Request (MUR) command . 21
5.6.6 Modify-Uecontext-Answer (MUA) command . 22
Annex A (informative): Change history . 23
History . 24

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3GPP TS 29.217 version 15.1.0 Release 15 5 ETSI TS 129 217 V15.1.0 (2019-10)
Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
Y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
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1 Scope
The present document provides the stage 3 specification of the Np reference point. The functional requirements and the
stage 2 specifications of the Np reference point are contained in 3GPP TS 23.203 [2]. The Np reference point lies
between the RAN Congestion Awareness Function (RCAF) and the Policy and Charging Rules Function (PCRF) for the
non-roaming case, between the RCAF and the H-PCRF for the home-routed scenario and between the RCAF and the V-
PCRF for the visited access scenario.
NOTE: If not specified explicitly, the PCRF also means H-PCRF for the home-routed scenario or V-PCRF in the
visited access scenario in the specification.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 23.203: "Policy and charging control architecture".
[3] 3GPP TS 29.213: "Policy and Charging Control signalling flows and QoS parameter mapping".
[4] IETF RFC 4005: "Diameter Network Access Server Application".
[5] IETF RFC 4006: "Diameter Credit Control Application".
[6] 3GPP TS 29.229: "Cx and Dx interfaces based on Diameter protocol; Protocol details".
[7] IETF RFC 3588: "Diameter Base Protocol".
[8] 3GPP TS 23.401: "GPRS enhancements for E-UTRAN access".
[9] 3GPP TS 23.060: "General Packet Radio Service (GPRS); Service description; Stage 2".
[10] 3GPP TS 29.215: "Policy and Charging Control (PCC) over S9 reference point; Stage 3".
[11] 3GPP TS 29.061: "Interworking between the Public Land Mobile Network (PLMN) supporting
packet based services and Packet Data Networks (PDN)".
[12] 3GPP TS 29.274: "3GPP Evolved Packet System. Evolved GPRS Tunnelling Protocol for EPS
(GTPv2)".
[13] ITU-T Recommendation E.212: "The international identification plan for mobile terminals and
mobile users".
[14] 3GPP TS 29.212: "Policy and Charging Control (PCC); Reference points".
[15] IETF RFC 7683: "Diameter Overload Indication Conveyance".
[16] IETF RFC 7944: "Diameter Routing Message Priority".
[17] IETF RFC 8583: "Diameter Load Information Conveyance".
[18] IETF RFC 6733: "Diameter Base Protocol".
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[19] IETF RFC 5719: "Updated IANA Considerations for Diameter Command Code Allocations".
[20] IETF RFC 2234: "Augmented BNF for syntax specifications".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following
apply. A term defined in the present document takes precedence over the definition of the same term, if any, in
3GPP TR 21.905 [1].
Home Routed Access: Roaming scenario where the PCEF is located in the HPLMN. In a Home Routed roaming
scenario, the UE obtains access to the packet data network from the HPLMN.
RAN user plane congestion: RAN user plane congestion occurs when the demand for RAN resources exceeds the
available RAN capacity to deliver the user data for a prolonged period of time.
NOTE: Short-duration traffic bursts is a normal condition at any traffic load level, and is not considered to be
RAN user plane congestion. Likewise, a high-level of utilization of RAN resources (based on operator
configuration) is considered a normal mode of operation and might not be RAN user plane congestion.
Visited Access (also known as local breakout): Roaming scenario where the PCEF is located in the VPLMN. In a
Visited Access Roaming scenario, the UE obtains access to the packet data network from the VPLMN.
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
3GPP TR 21.905 [1].
AF Application Function
ARR Aggregated RUCI Report Request
ARA Aggregated RUCI Report Answer
DRMP Diameter Routing Message Priority
H-PCRF Home PCRF
MUR Modify Uecontext Request
MUA Modify Uecontext Answer
NRR Non-Aggregated RUCI Report Request
NRA Non-Aggregated RUCI Report Answer
PCC Policy and Charging Control
PCRF Policy and Charging Rule Function
RCAF RAN Congestion Awareness Function
RUCI RAN User Plane Congestion Information
V-PCRF Visited PCRF
4 Np reference point
4.1 Overview
The Np reference point is located between the RCAF and the PCRF for the non-roaming scenario, between the RCAF
and the H-PCRF for the home-routed scenario and between the RCAF and the V-PCRF for the visited access scenario.
The Np reference point is used for:
- Reporting the RUCI from the RCAF to the PCRF;
- Provisioning the Reporting Restriction from the PCRF to the RCAF;
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- The User Equipment (UE) mobility between RCAFs;
- The removal of the UE context in the RCAF.
The stage 2 level requirements for the Np reference point are defined in 3GPP TS 23.203 [2].
Signalling flows related to Np interface are specified in 3GPP TS 29.213 [3].
Refer to Annex G of 3GPP TS 29.213 [3] for Diameter overload control procedures over the Np interface.
Refer to Annex J of 3GPP TS 29.213 [3] for Diameter message priority mechanism procedures over the Np interface.
Refer to Annex K of 3GPP TS 29.213 [3] for Diameter load control procedures over the Np interface.
4.2 Np reference model
The relationships between the involved functional entities are depicted in figure 4.2.1. The overall PCC architecture is
depicted in clause 3a of 3GPP TS 29.213 [3] .
Np
RCAF PCRF

Figure 4.2.1: Np reference model
NOTE: For the home-routed access scenario, the RCAF interacts with the H-PCRF. For the visited access
scenario, the RCAF interacts with the V-PCRF.
Figure 4.2.2: Void
Figure 4.2.3: Void
4.3 Functional elements
4.3.1 RCAF
The RCAF is a functional element which reports RAN User Plane Congestion Information (RUCI) via the Np interface
to the PCRF to enable the PCRF to take the RAN user plane congestion status into account for policy decisions. RUCI
includes the following information:
- The user id (e.g. IMSI) identifying the UE impacted by congestion;
- PDN ID for which congestion information is reported;
- Congestion level information (either congestion level value or congestion level set id) of the UE impacted by
congestion;
- eNodeB identifier, ECGI or SAI identifying the eNodeB, E-UTRAN cell or Service Area respectively, serving
the UE if a conditional restriction to restrict location reporting is not enabled.
NOTE 1: In case of E-UTRAN, whether the eNodeB identifier or the ECGI are included in the RUCI is up to
operator configuration in the RCAF.
The RCAF sends the RUCI to the PCRFs serving the UEs' PDN connections as follows:
- For a PDN connection in a non-roaming scenario the RCAF reports the RUCI to the PCRF;
- For a PDN connection in a local breakout scenario, based on operator configuration, the RCAF reports the RUCI
to the V-PCRF;
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- For a PDN connection in a home routed scenario, based on the roaming agreement with the HPLMN and
operator configuration, the RCAF reports the RUCI to the H-PCRF
NOTE 2: Reporting of congestion information to the HPLMN may be used e.g. in case of a group of PLMNs which
belong to a single business entity.
The RCAF determines whether a given PDN connection is served in a local breakout or a home routed roaming
scenario based on the APN operator identifier received as part of the APN information from the MME or the SGSN as
documented in 3GPP TS 23.401 [8] and 3GPP TS 23.060 [9], respectively.
NOTE 3: Operator configuration can be used to limit RUCI reporting on the Np interface to certain APNs only.
The RCAF maintains a context per user id and APN. The context is identified by the IMSI and the APN. It contains the
following information:
- The previously reported congestion level over the Np reference point;
- The reporting restrictions received from the PCRF. The reporting restrictions are stored by the RCAF until the
PCRF explicitly signals to remove the reporting restrictions.
- The logical PCRF id received from the PCRF to identify the PCRF that is the Np destination for the RCAF when
sending aggregate messages.
4.3.2 PCRF
The PCRF is a functional element that encompasses policy control decision and flow based charging control
functionalities.
The PCRF may receive RUCI from the RCAF as input for policy decisions of congestion mitigation. The PCRF may
provide, update or remove the reporting restrictions of RUCI, or stop or enable RUCI reporting for a given user id and
PDN ID. The PCRF may enable or disable the reporting of congestion location identifier as part of RUCI. The PCRF
may also remove the context at the RCAF for a given user id and PDN ID.
NOTE: Depending on the RUCI reporting interval configured in the RCAF, a UE can move outside the area
indicated without the RCAF immediately notifying the PCRF. In case the PCRF receives information
about the cell currently serving a UE via Np and Gx when the location change reporting is enabled, then
the information received via Gx is expected to take precedence.
4.3.3 H-PCRF
Functionality defined in clause 4.3.2 shall apply if UE is roaming with home-routed access scenario.
NOTE: Reporting of congestion information to the HPLMN can be used e.g. in case of a group of PLMNs which
belong to a single business entity.
4.3.4 V-PCRF
Functionality defined in clause 4.3.2 shall apply if UE is roaming with visited access scenario.
4.4 Procedures over Np reference point
4.4.1 RUCI Report
4.4.1.1 General
The RCAF shall perform the RUCI reporting to the PCRF when at least one of the following conditions applies:
- the RCAF detects a UE in the congestion area for the first time;
- a reporting restriction is enabled and the congestion level set id is changed;
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- a reporting restriction is not enabled and the congestion level value is changed;
- a conditional restriction to restrict location reporting is not enabled and the UE is in a congested area and the
location is changed; or
- the RCAF detects that the UE is no longer experiencing congestion (i.e. the UE is no longer detected in any of
the congested cells that the RCAF is monitoring).
The RCAF shall report the RUCI to the PCRF unless the RUCI reporting is disabled for the PDN ID or for the user id
and the PDN ID.
Two types of RUCI reports may be used on Np for transfer of congestion information from RCAF to PCRF: Non-
aggregated RUCI report and Aggregated RUCI report. If the RCAF does not know the destination PCRF for the user id
and PDN ID, the Non-aggregated RUCI report shall be used; otherwise the RCAF may use either the Non-aggregate
RUCI report or Aggregated RUCI report for the user id and PDN ID.
4.4.1.2 Non-aggregated RUCI report
For a Non-aggregated RUCI report, the RCAF shall send an NRR command to the PCRF by including the user id
within the Subscription-Id AVP, PDN ID within the Called-Station-Id AVP and a congestion level set id within the
Congestion-Level-Set-Id AVP if the reporting restriction was provided earlier or a congestion level value within the
Congestion-Level-Value AVP if the reporting restriction was not provided earlier at the command level. The RCAF
may also provide congestion location identifier of the UE within the Congestion-Location-Id AVP in the NRR
command. The RCAF shall also include the RCAF Identity within the RCAF-Id AVP in every NRR command for a
specific user id and PDN ID.
Once the PCRF receives the NRR command, the PCRF shall store the related info and respond with an NRA command
including the PCRF id within the PCRF-Address AVP. The PCRF may use the RUCI received from the RCAF as input
for policy decisions. When the RCAF receives the NRA command, the RCAF may store the PCRF id in the UE context
for this specific user id together with PDN ID for further aggregated RUCI report.
If the ReportRestriction feature is supported by both the RCAF and the PCRF, the PCRF may provide reporting
restrictions in the NRA command according to clause 4.4.2.
4.4.1.3 Aggregated RUCI report
For an Aggregated RUCI report, the RCAF shall aggregate the RUCIs of different user ids and PDN IDs that have the
same destination PCRF. The RCAF shall send an ARR command to the destination PCRF by including the PCRF id
within the Destination-Host AVP, one or more Aggregated-RUCI-Report AVP with a congestion level set id within the
Congestion-Level-Set-Id AVP if the reporting restriction was provided earlier or a congestion level value within the
Congestion-Level-Value AVP if the reporting restriction was not provided earlier, the PDN ID within the Called-
Station-ID AVP and a list of aggregated congestion information within the Aggregated-Congestion-Info AVP.
...