1. 1 MAPSUP in eHRPD Sources: ZTE Contact: Bi YiFeng (bi,yifeng@zte.com.cn)bi,yifeng@zte.com.cn Rajesh Bhalla (rabhalla@zteusa.com)rabhalla@zteusa.com ABSTRACT: A discussion paper for MAPSUP (Multiple PDN Connections to A Single APN ) in eHRPD system. Recommendation: Review and conceptually approve The contributing companies grant a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. The contributing companies are also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution. This document has been prepared by the contributing companies to assist in the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on contributors. The contributing companies specifically reserve the right to amend or modify the material contained herein and to any intellectual property of contributors other than provided in the copyright statement above.

2. 2 What is “MAPSUP”? MAPSUP is short for “Multiple PDN connections to the Same APN for PMIP-based Interfaces ”. It enables the UE to establish more than one PDN connection using a single APN in the situation that the S5/S8 interface between the S- GW and P-GW (for 3GPP access) or S2a/S2b interface between the AGW/ePDG and P-GW (for non-3GPP access) is PMIP-based. –MAPSUP work item is agreed in the R9 phase in 3GPP SA2. –In Release 8, PMIP-based interfaces (i.e. PMIP-based S5/S8, S2a and S2b) do not support this feature available using other equivalent interfaces (e.g. GTP-based S5/S8) in release 8. So this feature was deferred due Release 9. –3GPP2, LTE-eHRPD Interworking Revision A (X.P0057-A) is targeted to align with 3GPP Release 9, so the item MAPSUP is a important issue that should be studied.

3. 3 Use Cases Supporting multiple addresses by the UE/Public Router –The UE is used as a DSL-modem router that sits in the house with multiple-devices, e.g. laptops sitting behind the UE. The need is seen not to support NAT on the UE and allow for multiple IPv4 addresses and IPv6 HNPs to be provided to the UE. Also, these addresses and devices can join and leave independently at different times.(3GPP S2-081363, S2-083555 ) –A public router that sits in the carriage of a train with multiple UEs, e.g. laptops and Mobile phones, in the carriage. This allows multiple IPv4 addresses and IPv6 HNPs to be provided to the router, hence to multiple UEs in that carriage. Also, these addresses and UEs can join and leave independently at different times. Handover from a MAPSUP system to a non-MAPSUP system –If the UE hands over between 3GPP access and a eHRPD system and the UE has more than one PDN connection to a given APN in the source access and multiple PDN connections to a single APN are not supported via the target access, only one PDN connection to the given APN will be established in the target access, all other PDN connections to the APN should be released. (TS23.402)

4. 4 The solution in EPS system Problem statement: –In 3GPP R8, different PDN connections have different APN which is used in PCC interaction and PMIP interaction to associate the PCC session and PMIP tunnel. –In 3GPP R9, there are more than one PDN connections to a APN, so the APN is not enough to distinguish different PDN connections, and how to associate the PCC session to the correct PMIP tunnel is a problem needing to be solved. Solution statement –In 3GPP TS 23.402(R9), a conceptual solution is brought forward — to introduce a “PDN connection ID” into the 3GPP access or non-3GPP access systems, which is one and only to a PDN connection. The “PDN connection IDs” together with the APNs are used to distinguish different PDN connections and to associate the PCC sessions and PMIP tunnels. –In EPS, the “default bear ID” which is called “LBI (Linked Local ID)” is chosen as the “PDN connection ID”. The LBI is transported in “GW control session”, “IP- CAN session” and “PMIP signal”, so the PCRF can associate these sessions correctly using LBI and APN especially in the Handover procedures.

5. 5 An example in EPS system - 1 Procedure Description: –UE handovers to a new S-GW/BBERF (inter-S-GW handover) and UE have multiple PDN connections to a APN. The UE initiates the PDN connection establishment procedure to the target S-GW/BBBEF. The UE sends multiple “PDN connection request” messages to the MME, containing the same parameters (APN, attach type etc). –The MME allocates the LBIs to each PDN connections, and sends them to S-GW. –The S-GW/BBEFR sends the “GW control session (GCS) request” messages to the PCRF containing APN and LBI to establish the GCS(s). –The S-GW/BBERF sends PBU(s) to P-GW/PCEF containing LBI and APN. –After the P-GW receives the PBU(s), the P-GW matches the PDN address(es) which have been allocated before the HO according to the APN+ LBI for the PDN connections. Also, the P-GW can match the ICS to the right PMIP tunnel based on the APN+LBI. Then P-GW sends the IP-CAN session (ICS) modification messages to the PCRF to modify the ICS(s) containing the APN+LBI and UE’s PDN address. –The PCRF associates the ICS and GCS based on the LBI. –Finished all the operations, the ICS, GCS, PMIP tunnel and PDN connections have been associated with each others.

6. 6 An example in EPS system - 2 -------- 3GPP to eHRPD/non-3GPP Handover UE handovers from LTE to non-3GPP AGW/HSGW and UE have multiple PDN connections to a APN. The UE sends multiple “PDN connection request” messages containing the same parameters (APN, attach type etc).. The AGW/HSGW allocates the PDN connection ID(PCID) to each PDN connection, and sends the “ GCS request” messages to the PCRF containing APN and PCID to establish the GCS(s). The AGW/HSGW sends PBU(s) to P-GW/PCEF containing PCID. After the P-GW receives the PBU(s), it chooses the IP address(es) which have been allocated before the HO randomly for the PDN connections. And the P-GW sends the ICS establishment messages to the PCRF to establish the ICS(s) containing the APN, PCID and UE’s PDN address. The PCRF associates the ICS and GCS based on the PCID. Finished all the operations, the ICS, GCS, PMIP tunnel and PDN connections have been associated with each others.

7. 7 What are the effects to the eHRPD system? The remained problems that need to be solved in eHRPD are: –How to define a PCID to distinguish the different PDN connection using the same APN in eHRPD? –How many data forwarding tunnels should be established during a optimized Handover call flow if there are multiple PDN connection associated with a APN? –Other issues?

8. 8 Proposal MAPSUP item should be started in X.P.0057 A in TSG-X now. The principles (using PDN connection ID) made in 3GPP should be adopted and the questions that have not been solved in 3GPP should be studied here. The issues listed in previous page should be considered as the next step.

9. 9 Thanks!