ETSI TS 123 261 V15.0.0 (2018-06)

ETSI TS 123 261 V15.0.0 (2018-06)
TECHNICAL SPECIFICATION
Universal Mobile Telecommunications System (UMTS);
LTE;
IP flow mobility and seamless
Wireless Local Area Network (WLAN) offload;
Stage 2
(3GPP TS 23.261 version 15.0.0 Release 15)
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3GPP TS 23.261 version 15.0.0 Release 15 1 ETSI TS 123 261 V15.0.0 (2018-06)
Reference
RTS/TSGS-0223261vf00
Keywords
LTE,UMTS
ETSI
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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, UMTS identities or

GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.

The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under

In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and

"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of

"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

Intellectual Property Rights ................................................................................................................................ 2

Foreword ............................................................................................................................................................. 2

Modal verbs terminology .................................................................................................................................... 2

Foreword ............................................................................................................................................................. 4

1 Scope ........................................................................................................................................................ 5

2 References ................................................................................................................................................ 5

3 Definitions and abbreviations ................................................................................................................... 6

3.1 Definitions .......................................................................................................................................................... 6

3.2 Abbreviations ..................................................................................................................................................... 6

4 Architecture model and concepts ............................................................................................................. 6

4.1 General concepts ................................................................................................................................................ 6

4.2 Architecture reference model ............................................................................................................................. 7

4.2.1 Non-roaming architecture ............................................................................................................................. 7

4.2.1 Roaming architecture .................................................................................................................................... 7

4.3 High level functions ........................................................................................................................................... 7

4.3.1 S2c and H1 extensions for IP flow mobility ................................................................................................. 7

4.3.1.1 General .................................................................................................................................................... 7

4.3.1.2 DSMIPv6 enhancements ......................................................................................................................... 7

4.3.2 Policy provisioning for Inter-system mobility and WLAN offload .............................................................. 8

4.3.3 Policy Control and Charging support ........................................................................................................... 8

4.3.4 Local Operating Environment Information ................................................................................................... 8

5 IP Flow Mobility procedures and flows ................................................................................................... 9

5.1 General ............................................................................................................................................................... 9

5.2 PDN connection establishment over first access ................................................................................................ 9

5.2.1 General .......................................................................................................................................................... 9

5.2.2 PDN connection establishment over 3GPP access ........................................................................................ 9

5.2.3 PDN connection establishment over WLAN .............................................................................................. 10

5.3 Addition of an access to a PDN connection ..................................................................................................... 11

5.3.1 General ........................................................................................................................................................ 11

5.3.2 Addition of WLAN access .......................................................................................................................... 11

5.3.3 Addition of 3GPP access ............................................................................................................................ 13

5.4 IP flow mobility within a PDN connection ...................................................................................................... 14

5.4.1 General ........................................................................................................................................................ 14

5.4.2 IP flow mobility within a PDN connection with network-initiated dynamic PCC ..................................... 14

5.4.3 IP flow mobility within a PDN connection with UE-initiated resource request ......................................... 16

5.5 Removal of an access from a PDN connection ................................................................................................ 17

5.5.1 UE-initiated removal of an access from a PDN connection ........................................................................ 17

5.5.2 HA-initiated removal of an access from a PDN connection ....................................................................... 18

5.6 Addition of one access for multiple PDN connections to the same APN ......................................................... 20

5.7 Detach and PDN disconnection procedures ..................................................................................................... 20

Annex A (informative): Change history ............................................................................................... 21

History .............................................................................................................................................................. 22

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

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.

This document specifies the Stage 2 system description for IP flow mobility between a 3GPP and a WLAN. The

technical solution is based on the working principles of DSMIPv6 [2] and it is applicable to both the Evolved Packet

The specification covers the system description of seamless WLAN offload and IP flow mobility between 3GPP and

WLAN as well as the respective interactions with the PCC and ANDSF frameworks. The system description for non

This document specifies also the detailed extensions to S2c [3] and H1 [4] reference points for IP flow mobility. The

extensions to the PCC and to the ANDSF framework are specified respectively in 3GPP TS 23.203 [5] and in

The following documents contain provisions which, through reference in this text, constitute provisions of the present

- References are either specific (identified by date of publication, edition number, version number, etc.) or

- 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

[2] IETF RFC 5555 (June 2009): "Mobile IPv6 support for dual stack Hosts and Routers (DSMIPv6)".

[4] 3GPP TS 23.327: "Mobility between 3GPP-Wireless Local Area Network (WLAN) interworking

[6] IETF RFC 4877 (April 2007): "Mobile IPv6 Operation with IKEv2 and the Revised IPsec

[8] IETF RFC 6089 (January 2011): "Flow Bindings in Mobile IPv6 and Network Mobility (NEMO)

[9] 3GPP TS 23.234: "3GPP System to Wireless Local Area Network (WLAN) Interworking; System

[10] 3GPP TS 23.401: "General Packet Radio Service (GPRS) enhancements for Evolved Universal

[11] 3GPP TS 23.060: "General Packet Radio Service (GPRS); Service description; Stage 2".

For the purposes of the present document, the terms and definitions given in TR 21.905 [1] and the following apply.

The following terms used in this Technical Specification are defined in RFC 6275 [14]: Home Address, Care-of

The following terms used in this Technical Specification are defined in TS 23.402 [3]: Home network prefix.

Home Agent: The Home Agent functionality consists in the DSMIPv6 anchor point functionality described in

RFC 5555 [2] and in RFC 4877 [6] and the extensions defined in RFC 5648 [7] and RFC 6089 [8]. As per

TS 23.402 [3], the HA functionality is located in the PDN Gateway. As per TS 23.327 [4] the HA functionality can be

Local Operating Environment Information: This is a set of implementation specific parameters which describe the

routing address: A routable IP address. In DSMIPv6 this is either the CoA (visited link case) or the HoA (in home link

routing filter: A set of packet flow IP header parameter values/ranges used to identify one or more IP flows for routing

For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply.

This document specifies a mechanism for a UE to simultaneously connect to 3GPP access and WLAN and exchange

different IP flows belonging to the same PDN connection through different accesses. The mechanism also enables

seamless IP flow mobility, with IP flows belonging to the same or different applications being moved seamlessly

The solution allows the operator to indicate how the IP flows are routed through the available access systems and to

selectively offload some traffic (e.g. best effort traffic) to WLAN while using UTRAN or E-UTRAN for other traffic

(e.g. traffic with specific QoS requirements). This is usually referred to as WLAN offload.

The technical solution is based on DSMIPv6, RFC 5555 [2] and is applicable to both the Evolved Packet System and

the I-WLAN mobility architecture. Since the solution is based on DSMIPv6, IP address preservation and session

The baseline architecture reference model for IP flow mobility when EPS is deployed in the non roaming case is

The baseline architecture reference model for IP flow mobility when I-WLAN mobility is deployed in the non roaming

The baseline architecture reference model for IP flow mobility when EPS is deployed in the roaming case is specified in

The baseline architecture reference model for IP flow mobility when I-WLAN mobility is deployed in the roaming case

The granularity of access system connectivity and inter system mobility based on TS 23.402 [3] and TS 23.327 [4] is

per PDN connection basis. This implies that when a handover occurs all the IP flows belonging to the same PDN

With IP flow mobility it is possible to have a finer granularity in access system connectivity and inter system mobility:

the handover procedures can be applied to a single or multiple IP flows belonging to the same PDN connection. This

implies that some IP flows of one PDN connection can be routed via one access system while simultaneously some IP

To achieve IP flow mobility the inter-system mobility signalling is enhanced in order to carry routing filters. The

extensions to DSMIPv6 mobility signalling needed to carry routing filters when the UE is connected to multiple

accesses simultaneously are specified in RFC 5648 [7] and RFC 6089 [8] and are applicable to both S2c and H1.

When a UE configures different IP addresses on multiple accesses, it can register these addresses with the HA as CoAs

To register multiple bindings, the UE generates a Binding ID (BID) for each CoA and stores the BID in the binding

update list. The UE then registers its CoAs by sending a Binding Update (BU) with a Binding Identifier mobility option.

The BID is included in the Binding Identifier mobility option. When the UE is on the home link in one of the access, the

When the HA receives the BU with a Binding Identifier mobility option, it copies the BID from the mobility option to

the corresponding field in the Binding Cache entry. If there is an existing Binding Cache entry for the UE, and if the

BID in the BU does not match the one with the existing entry, the HA creates a new Binding Cache entry for the new

Based on this extension, a typical Binding Cache in HA according to this specification in case the UE is not on the

NOTE: A BID is only unique for a given HoA, i.e. different mobile nodes can use the same BID value.

In order to route IP flows through a specific access, the UE needs to request to store routing filters for that access at the

HA: the UE includes the Flow Identification (FID) mobility option in the BU message as defined in RFC 6089 [8]. The

FID option defines a routing rule which contains a routing filter and a routing address. The routing address (either CoA

or HoA) is indicated by the BID. The routing filter is included in the DSMIPv6 signalling as described in

RFC 6088 [12]. The routing filters are unidirectional and can be different for uplink and downlink traffic.

It is assumed that between UE and the Home Agent function there is always a default routing address via which packets

not matching any specific routing filter are routed. The UE provides a relative priority with each BID, where the BID

with the highest priority is the default route. The UE may update the priority of a BID during IP flow mobility

To install/remove/move an IP flow, the UE shall create a new IP flow binding or remove/update the IP flow binding at

the HA by using DSMIPv6 signalling as specified in RFC 5555 [2], RFC 5648 [7] and RFC 6089 [8].

An example of a typical Binding Cache in HA with routing filters is shown in Table 4.3.1.2-2. Note that a FID is only

unique for a given HoA, i.e. different PDN connections can use the same FID value. Each flow binding entry contains a

NOTE: This clause shows only a conceptual representation of the binding cache. The actual format is

In order to allow the operator to indicate to the UE through which access technology IP flows are expected to be routed,

inter system routeing policies are introduced in TS 23.402 [3]. Such policies can be defined per APN, per IP flow class

under any APN or per IP flow class under a specific APN and can be provided to the UE either through ANDSF or by

For IP flows that are routed over WLAN, the inter system routeing policies also specify whether the traffic should be

When IP flow mobility is used and PCC is deployed, the PCC architecture is enhanced to handle multiple simultaneous

access connections for a single IP-CAN session. These enhancements require the PDN GW to keep the PCRF up to date

The detailed description of the normative procedures for PCC enhancements can be found in TS 23.203 [5].

In addition to operator policy and user preferences, the UE may take into account the Local Operating Environment

The actual Local Operating Environment Information is implementation dependent and may comprise of such items as,

radio environment information, quality of IP connection, application specific requirements, power considerations, etc.

This section describes the IP flow mobility procedures for different scenarios. The call flows are described in a common

way for I-WLAN and EPS and the procedures which are applicable to EPS only are marked as optional and identified

as not applicable to an I-WLAN mobility deployment. Furthermore the call flows do not differentiate between trusted or

untrusted accesses as the IP flow mobility procedures are common as soon as the UE configures a Care-of Address.

This clause specifies the additional UE procedures when establishing a PDN connection through a 3GPP or through a

WLAN access when the UE supports IP flow mobility. In these flows it is assumed that the UE has not established the

NOTE: In the rest of the document the PDN connection establishment procedure is meant to be PDP context

The UE performs the initial PDN connection establishment to a 3GPP access as shown in Figure 5.2.2-1. This

1. The initial PDN establishment procedure is performed by the UE according to TS 23.401 [10] or TS 23.060 [11],

depending if the PDN connection establishment is to EPS or GPRS. During this step an IPv4 address and/or an

2. The UE performs HA discovery, DSMIPv6 bootstrapping and the home link detection procedure as described in

If the UE requests the home network prefix in the Protocol Configuration Option (as in TS 23.402 [3]), the UE

shall requests in the Protocol Configuration Option an indication of HA support of IP flow mobility.

If the UE obtains the home network prefix using the IKEv2 procedure, the UE shall use IKEv2 signaling to

indicate IFOM support. The HA supporting IFOM shall use IKEv2 signaling to confirm the IFOM support.

If the HA does not support IFOM, the UE shall disable IFOM capabilities for that PDN connection.

The presence of ANDSF inter-system routing policies for a given PLMN may be considered by the UE as an

implicit indication that the Home Agents of that PLMN support IP flow mobility. If the UE has ANDSF inter-

system routing policies, the UE may skip the IKEv2 and PCO procedures to check the IFOM support of the PDN

3. If the UE detects it is not on the home link, the UE sends a DSMIPv6 Binding Update (HoA, CoA, Lifetime,

BID) message to the HA as specified in RFC 5555 [2] and RFC 5648 [7]. The inclusion of the BID mobility

option at this stage is an indication that the UE supports IP Flow Mobility extensions. The UE may also include

NOTE: This step cannot happen in case IP flow mobility is used in EPS as 3GPP is always the home link in EPS.

4. The HA validates the BU, installs the IP flow mobility routing rules, establishes the DSMIPv6 bindings and

The UE performs the initial PDN connection establishment over a WLAN access as shown in Figure 5.2.3-1.