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Content for  TS 23.261  Word version:  16.0.0

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5  IP Flow Mobility procedures and flows

5.1  General

This clause 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.

5.2  PDN connection establishment over first access

5.2.1  General

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 PDN connection through any access yet.

5.2.2  PDN connection establishment over 3GPP access

The UE performs the initial PDN connection establishment to a 3GPP access as shown in Figure 5.2.2-1. This procedure applies independently whether the UE attaches to EPS or GPRS.
(not reproduced yet)
Figure 5.2.2-1: PDN connection procedure over 3GPP access
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Step 1.
The initial PDN establishment procedure is performed by the UE according to TS 23.401 or TS 23.060, depending if the PDN connection establishment is to EPS or GPRS. During this step an IPv4 address and/or an IPv6 address/prefix is assigned to the UE.
Step 2.
The UE performs HA discovery, DSMIPv6 bootstrapping and the home link detection procedure as described in TS 23.402 or TS 23.327.
If the UE requests the home network prefix in the Protocol Configuration Option (as in TS 23.402), 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 GW for the PDN GWs residing in the PLMN where the ANDSF policies are valid.
Step 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 and RFC 5648. 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 some FID mobility options as described in RFC 6089.
Step 4.
The HA validates the BU, installs the IP flow mobility routing rules, establishes the DSMIPv6 bindings and sends a BA to the UE per RFC 5555, RFC 5648 and RFC 6089.
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5.2.3  PDN connection establishment over WLANWord‑p. 10

The UE performs the initial PDN connection establishment over a WLAN access as shown in Figure 5.2.3-1.
(not reproduced yet)
Figure 5.2.3-1: PDN connection procedure over non-3GPP access
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Step 1.
The UE connects to the WLAN and configures an IPv4 address and/or an IPv6 address/prefix. Depending on the specific scenario considered the UE attaches either to a trusted WLAN, an ePDG via an untrusted WLAN or to a PDG via a I-WLAN access as specified in TS 23.402 or TS 23.327. If the UE connects to PDG or ePDG, an IPv4 address and/or an IPv6 address/prefix is assigned to the UE.
Step 2.
If the UE connects to a Trusted non-3GPP access and dynamic PCC is deployed, a GW control session may be established as specified in TS 23.203.
Step 3.
The UE performs HA discovery, DSMIPv6 bootstrapping and the home link detection procedure as described in TS 23.402 or TS 23.327.
During the home link detection procedure in IKEv2, the UE shall use IKEv2 signalling to indicate IFOM support. The HA supporting IFOM shall use IKEv2 signalling 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 GW for the PDN GWs residing in the PLMN where the ANDSF policies are valid.
Step 4.
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 and RFC 5648. The inclusion of the BID mobility option at this stage is an indication that the UE supports IP Flow Mobility extensions. The BID mobility option contains the Binding ID of the WLAN access. The UE may also include some FID mobility options as described in RFC 6089.
Step 5.
If the HA function is located in the PDN GW and dynamic PCC is deployed, the PDN GW performs an IP-CAN session establishment procedure with the PCRF as specified in TS 23.203.
Step 6.
The HA validates the BU, installs the IP flow mobility routing rules, establishes the DSMIPv6 bindings and sends a BA to the UE per RFC 5555, RFC 5648 and RFC 6089.
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5.3  Addition of an access to a PDN connectionWord‑p. 11

5.3.1  General

This clause specifies the additional procedures for adding an access to an existing PDN connection over a 3GPP access or a WLAN access when the UE supports IP flow mobility. In these flows it is assumed that the UE has performed a PDN Connection establishment procedure through one access as specified in clause 5.2. Subsequently the UE attaches to a second access and starts using both accesses for the same PDN connection. As a result the UE is simultaneously connected via both accesses and a set of traffic flows are routed through one access while the remaining traffic flows are routed through the other access.
Non-roaming, home routed roaming and Local Breakout cases are supported by this procedure. The AAA proxy and vPCRF are only used in the case of home routed roaming and Local Breakout. In non-roaming scenarios, the AAA proxy and vPCRF are not involved.
The optional interaction steps between the gateways and the PCRF in the procedures only occur if dynamic policy provisioning is deployed in EPC. These steps are never present when the solution is applied to I-WLAN mobility architecture according to TS 23.327.
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5.3.2  Addition of WLAN accessWord‑p. 12

After successfully attachment to 3GPP access, the UE has established a PDN connection over 3GPP access as specified in clause 5.2.2. Subsequently the UE performs the WLAN attachment, and requests to establish a PDN connection using the same APN, and attempts to use both accesses for the same PDN connection simultaneously. The WLAN access may be considered as the UE's foreign link from DSMIPv6 perspective.
(not reproduced yet)
Figure 5.3.2-1: Addition of WLAN access to the PDN connection
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The signalling flow above shows the particular case where the UE is first connected to a 3GPP access and then it requests addition of a WLAN access.
Step 1.
The UE discovers a WLAN and connects to it and configures an IPv4 address and/or an IPv6 address/prefix according to TS 23.402 or TS 23.327, depending whether the WLAN access is used in the context of EPC or I-WLAN mobility architecture.
Step 2.
The UE performs HA discovery, DSMIPv6 bootstrapping and DSMIPv6 home link detection procedure according to TS 23.402 unless already performed in the 3GPP access.
Step 3.
The UE sends a DSMIPv6 Binding Update (HoA, CoA, Lifetime, BID, FID, flow description) message to the HA over the WLAN access. The UE may include the requested routing rules via the FID mobility option with both the routing filters and the BID (which includes the routing address) as specified in IETF RFC 5555, IETF RFC 5648 and RFC 6089. The UE can include more than one routing rule by including multiple FID mobility options in the Binding Update. The DSMIPv6 Binding Update also contains an indication which indicates that the home link (3GPP access) is still connected and also the BID mobility options which identify that one binding is associated with the home address (3GPP access) and the other with the Care-of-Address from the WLAN access. The UE also indicates in the Binding Update which is the default binding where the HA should route packets not matching any FID as specified in RFC 6089.
Step 4.
In case the HA function is located in the PDN GW and dynamic PCC is deployed, the PDN GW sends an IP-CAN session modification request to the PCRF. In this request, the PDN GW provides the updated routing rules to the PCRF. The PCRF stores the mapping between each SDF and its routing address.
Step 5.
If the HA function is located in the PDN GW, based on the successful establishment of resources at the BBERF, the PCRF sends an acknowledgement to the PDN GW, including updated PCC rules if appropriate.
Step 6.
The HA creates a DSMIPv6 binding, installs the IP flow routing rules and sends a Binding Acknowledgment (Lifetime, HoA, CoA, BID, FID) as specified in RFC 5555, RFC 5648 and RFC 6089, to indicate which routing rules requested by the UE are accepted.
The PDN GW may send message 6 before receiving the reply from PCRF in message 5.
Step 7.
Based on the IP-CAN session modification request (if step 4 was performed), the PCRF ensures that the relevant QoS rules for the SDFs are installed in the target BBERF. This is done by a GW control session and QoS rules provision procedure as specified in TS 23.203.
Step 8.
In case the HA function is located in the PDN GW, appropriate 3GPP resource release procedures are executed for the resources associated with the flows that were moved away from the 3GPP source access. This procedure may be triggered by the PCRF via a GW control session and QoS rules provision procedure if PMIPv6 is used on S5 and it may be triggered by the PDN GW in case GTP is used on S5.
If the HA function is implemented in I-WLAN mobility, the UE may initiate GPRS resource release procedures for those resources that were moved away from the 3GPP source access, as specified in TS 23.060.
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5.3.3  Addition of 3GPP accessWord‑p. 13

After successfully attachment to WLAN access, the UE has established a PDN connection over WLAN as specified in clause 5.2.3. As the UE detected the WLAN access is not the home link from DSMIPv6 perspective, DSMIPv6 signalling was triggered over the WLAN access.
Subsequently, as described in this clause, the UE performs the initial attachment procedure or PDN Connection establishment procedure over a 3GPP access and establishes a PDN connection using the same APN, as described in TS 23.060, TS 23.401 or TS 23.402. As the UE has indicated IP flow mobility during the initial attachment over WLAN, the 3GPP access attachment completion shall not trigger the DSMIPv6 binding deregistration.
(not reproduced yet)
Figure 5.3.3-1: Addition of 3GPP access to the PDN connection
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The signalling flow above shows the particular case where the UE is first connected to a WLAN access and then it requests addition of a 3GPP access.
Step 1.
The UE discovers a 3GPP access and performs the Attach or PDN Connection establishment procedure according to TS 23.401 or TS 23.060. Specifically, the UE sets the Request Type to Handover to facilitate the MME selects the same PDN GW/HA as the UE connects in WLAN Access. Since the UE has indicated IP flow mobility support during the initial attachment over WLAN, the HA shall not deregister the DSMIPv6 binding by sending a Binding Revocation Indication towards the WLAN access.
Step 2.
The UE sends a DSMIPv6 Binding Update (HoA, CoA, Lifetime, BID, FID, flow description) message to the HA over the 3GPP access. The UE may include the requested routing rules via the FID mobility option with both the routing filters and the BID (which includes the routing address) as specified in RFC 5555, RFC 5648 and RFC 6089. If the 3GPP access is the home link, the UE sets the 'H' flag in the respective BID mobility option, as specified in RFC 6089. The UE can include more than one routing rule by including multiple FID mobility options in the Binding Update. The UE also indicates in the Binding Update which is the default binding where the HA should route packets not matching any FID as specified in RFC 6089.
Step 3.
In case the HA function is located in the PDN GW and dynamic PCC is deployed, the PDN GW sends an IP-CAN session modification request to the PCRF. In this request, the PDN GW provides the updated routing rules to the PCRF. The PCRF stores the mapping between each SDF and its routing address.
Step 4.
If the HA function is located in the PDN GW, based on the successful establishment of resources at the BBERF, the PCRF sends an acknowledgement to the PDN GW, including updated PCC rules if appropriate.
Step 5.
The HA sends a Binding Acknowledgment (Lifetime, HoA, CoA, BID, FID) as specified in RFC 5555, RFC 5648 and RFC 6089, to indicate which routing rules requested by the UE are accepted.
The PDN GW/HA may send message 5 before receiving the reply from PCRF in message 4.
Step 6.
Based on the IP-CAN session modification request (if step 3 was performed), the PCRF ensures that the relevant QoS rules for the SDFs are installed in the target BBERF. This is done by a GW control session and QoS rules provision procedure as specified in TS 23.203.
Step 7.
In case the HA function is located in the PDN GW, appropriate 3GPP bearer setup or modification procedures are executed for the resources associated with the flows that were moved onto the 3GPP access. This procedure may be triggered by the PCRF via a GW control session and QoS rules provision procedure if PMIPv6 is used on S5 and it may be triggered by the PDN GW in case GTP is used on S5.
If the HA function is implemented in I-WLAN mobility, the UE may initiate GPRS bearer setup or modification procedures for those resources that were moved onto the 3GPP access, as specified in TS 23.060.
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