Mobile IPv6 deployment opportunities in next generation 3GPP networks. I. Guardini E. Demaria M. La Monaca

Transcription

1 Mobile IPv6 deployment opportunities in next generation 3GPP networks I. Guardini E. Demaria M. La Monaca

2 Overview of SAE/LTE Terminology SAE (System Architecture Evolution): core network/system aspects LTE (Long Term Evolution): new radio access (E-UTRAN) Main system characteristics support for packet services only OFDM radio technology peak throughput per user : 100 Mbps DL and 50 Mbps UL (with a 20 MHz channel width) multi-access core network: GERAN, UTRAN, E-UTRAN and non-3gpp Specifications to be completed by

3 Logical architecture: non roaming Legacy Networks UTRAN GERAN 2G/3G SGSN HSS S3 S6a S1 (CP) MME S4 S7 PCRF Rx+ E-UTRAN enb enb X2 S10 S1 (UP) S11 Serving Gateway S5 S5 Gateway SGi S2b Operator IP services (e.g. IMS, PSS,..) enb: MME: evolved Node B Mobility Management Entity (similar to the control part of the SGSN) : access gateway towards Packet Data Networks (similar to the GGSN) Trusted IP access S2a epdg Untrusted IP access SGi: interface towards Internet/Intranet (equivalent to Gi interface in GPRS) 3

4 Interworking with accesses (I) SAE supports both host-based and network-based mobility management solutions Dual-Stack MIPv6 (host-based) Proxy MIPv6 and MIPv4 in Foreign Agent mode (network-based) works as MIP/PMIP Home Agent when connected to a 3GPP access the UE can be assumed to be at home in MIP sense mobility within 3GPP accesses (E-UTRAN, UTRAN and GERAN) is managed in a network-based fashion using 3GPP-specific protocols service continuity is guaranteed in case the UE moves from a 3GPP access to a access (or vice versa) the UE communicates using the same IP address independently of the access network it is attached to 4

5 Interworking with accesses (II) SAE distinguishes between trusted and untrusted non 3GPP accesses It is up to the operator to decide if a access is trusted or untrusted the decision is not based just on the access network technology but may depend also on business considerations Interworking with an untrusted access is performed via an evolved PDG (epdg) the epdg is similar to a VPN concentrator the UE has to establish an IPsec tunnel with the epdg to access operator s services the epdg may implement IP mobility protocols (e.g. PMIPv6) 5

6 Interworking with accesses (III) Interworking with a trusted access is performed using a more lightweight procedure the UE does not need to establish an IPsec tunnel with the epdg in advance MIP or PMIP protocols can be used directly between the access network and the SAE core network the access gateway (e.g. ASN in case of mobile WiMAX) can run PMIPv6 6

7 Interworking with accesses (IV) 2G/3G SGSN HSS S3 S6a S1 (CP) MME S4 S7 PCRF Rx+ Wx* E-UTRAN S10 S11 S1 (UP) Serving Gateway HA Gateway SGi Operator IP services (e.g. IMS, PSS,..) S2b S6c S2c S2a epdg Wm* 3GPP AAA Server Trusted/untrusted (host-based) Trusted non 3GPP IP access (network-based) Untrusted non 3GPP IP access (network-based) Wa* Ta* UE 7

8 Protocols on interfaces The protocols that have been selected for mobility between 3GPP and accesses are S2a reference point (trusted accesses): Proxy Mobile IPv6 and Mobile IPv4 in Foreign Agent mode Mobile IPv4 in FA mode was requested by CDMA2000 operators (e.g. Verizon), that want to re-use their already deployed Mobile IPv4 infrastructure S2b reference point (untrusted accesses): Proxy Mobile IPv6 with dual-stack extensions S2c reference point (host-based mobility on trusted/untrusted accesses): Dual-Stack Mobile IPv6 (DSMIPv6) the usage of Mobile IPv4 in co-located mode is still under consideration 8

9 Interworking scenarios: non roaming S1u, S4, S11 3GPP Serving access S5 SGi S1u, S4, S11 3GPP Serving access S5 SGi Proxy Mobile IPv6 or MIPv4 in FA mode Dual-Stack Mobile IPv6 S2a S2b S2c S2c Network-based Mobility epdg Host-based Mobility epdg Trusted Untrusted Trusted Untrusted UE UE 9

10 Interworking scenarios: roaming (I) S1u, S4, S11 3GPP Serving access S5 SGi S1u, S4, S11 3GPP Serving access S5 SGi HPLMN Proxy Mobile IPv6 S8b HPLMN GTP or Proxy Mobile IPv6 S8a/b VPLMN 3GPP access S1u, S4, S11 Serving VPLMN 3GPP access S1u, S4, S11 Serving S2a PMIPv6 or MIPv4 in FA mode S2b Proxy Mobile IPv6 S2a S2b epdg epdg Trusted Untrusted Network-based Mobility Trusted Untrusted UE UE 10

11 Interworking scenarios: roaming (II) S1u, S4, S11 3GPP Serving access S5 SGi HPLMN GTP or Proxy Mobile IPv6 S8a/b VPLMN 3GPP access S1u, S4, S11 Serving S2c S2c Dual-Stack Mobile IPv6 epdg Host-based Mobility Trusted UE Untrusted 11

12 Interworking scenarios: roaming (III) S1u, S4, S11 3GPP Serving access HPLMN VPLMN Host-based Mobility 3GPP access S5 Proxy Mobile IPv6 S1u, S4, S11 S2c Trusted UE Serving SGi S8b S2c epdg Untrusted This scenario has not been officially accepted yet the Serving works as a local mobility anchor and runs PMIPv6 with the the home address is provided by the (i.e. the real HA) data traffic is anchored on the the Serving handles local mobility through DSMIPv6 the visited operator can use the Serving to enforce policies (e.g. charging) not clear how to handle Serving relocation when the UE moves across VPLMNs 12

13 PMIPv6/MIPv6: summary of usage scenarios Access (S2a/b) SGi (S2c) PMIPv6 SGi Roaming and non roaming DSMIPv6 Non 3GPP Accesses Cascade of PMIPv6 tunnels Access (S2a/b) Serving (S8b) SGi PMIPv6 PMIPv6 Roaming (S2c) Serving (S8b) SGi DSMIPv6 PMIPv6 Cascade of DSMIPv6 and PMIPv6 tunnels 13

14 Roaming with or without local anchor Option A: no local anchor HPLMN has to interface via PMIPv6 with all As in VPLMN complicates the establishment and maintenance of roaming agreements Option B: local anchor in HPLMN needs to interface via PMIPv6 just with the anchor point in VPLMN simplifies the establishment of roaming agreements the visited operator can exploit the local anchor to enforce policies on UE s data traffic A No local anchor PMIPv6 (S2a) HPLMN B Local anchor PMIPv6 (S8b) HPLMN VPLMN Non 3GPP As Non 3GPP As PMIPv6 (S2a) Serving VPLMN BSs BSs 14

15 Attach over S2a: trusted access (I) 15

16 Attach over S2a: trusted access (II) Step by step description of the procedure 1. The initial Non-3GPP access specific L2 procedures are performed 2. The EAP authentication procedure for network access is performed involving the UE, trusted non-3gpp IP Access and the 3GPP AAA Server. In the roaming case, there may be several AAA proxies involved. The information is returned as part of the reply from the 3GPP AAA Server to the MAG in the trusted non-3gpp access 3. After successful authentication and authorization, the L3 attach procedure is triggered 4. MAG function of Trusted Non-3GPP IP Access sends Proxy Binding Update message to 5. The selected informs the 3GPP AAA Server of its address 16

17 Attach over S2a: trusted access (III) Step by step description of the procedure (cont ed) 6. The processes the proxy binding update and creates a binding cache entry for the UE. The allocates IP address for the UE. The then sends a proxy binding acknowledgement to the MAG function in Trusted Non-3GPP IP Access, including the IP address(es) allocated for the UE 7. The PMIPv6 tunnel is set up between the Trusted Non-3GPP IP Access and the 8. L3 attach procedure is completed. IP connectivity between the UE and the is set for uplink and downlink directions 17

18 Attach over S2b: untrusted access UE epdg HSS/ AAA 1 IKEv2 authentication and tunnel setup Authentication and Authorization 2 Proxy BU (MN-ID, IP addr Req) 3 Update Address 4 Proxy Binding Ack (IP addr) 5 IPsec tunnel setup completion 6 IKEv2 (IP Address Configuration) 7 IPsec Tunnel PMIP Tunnel 18

19 Attach over S2b/S8b: cascade of tunnels (I) UE epdg Serving 3GPP AAA Proxy HSS/ AAA 1 IKE_AUTH Authentication Authentication and Authorization Authentication and Authorization 2 Proxy BU ( MN-ID, IP Addr Request ) 3 Proxy BU ( MN-ID, IP Addr Req) 4 Update Address 5 Proxy Binding Ack (IP Addr 6 Proxy Binding Ack IP Addr) 7 IPsec tunnel setup completion 8 IKEv2 (IP Address Configuration) 9 IPsec Tunnel PMIP Tunnel PMIP Tunnel 19

20 Attach over S2b/S8b: cascade of tunnels (II) Step by step description of the procedure 1. The IKEv2 tunnel establishment procedure is started by the UE. The epdg IP address to which the UE needs to form IPsec tunnel is discovered via DNS query. The information is returned as part of the reply from the 3GPP AAA Proxy to the epdg. This may entail an additional name resolution step, issuing a request to a DNS Server 2. The epdg sends the PBU message to the Serving 3. The visited Serving processes the proxy binding update and creates a binding cache entry for the UE. Then the visited Serving sends the PBU message to the using its own address as the MAG address. Note that the binding cache entry on the Serving does not yet have the UE s IP address information. This information will be added to the binding cache entry after step 4 20

21 Attach over S2b/S8b: cascade of tunnels (III) Step by step description of the procedure (cont ed) 4. The selected informs the 3GPP AAA Server of its address 5. The processes the proxy binding update and creates a binding cache entry for the UE. The allocates an IP address for the UE. The then sends a proxy binding ack to the Serving, including the IP address allocated for the UE. Once the Serving processes the proxy Binding Ack, it stores the UE s IP address information in the binding cache entry 6. After the Proxy BU/Proxy BAck is successful, there is a PMIPv6 tunnel setup between the Serving and the 7. The epdg continues with the IKE_AUTH exchange 21

22 Attach over S2b/S8b: cascade of tunnels (IV) Step by step description of the procedure (cont ed) 8. The epdg sends the final IKEv2 message with the IP address in IKEv2 Configuration payloads. The IP address sent in the IKEv2 configuration payload is the same address that the epdg received in the Proxy Binding Ack message 9. IP connectivity from the UE to the is now setup any packet in the uplink direction is tunneled to the epdg by the UE using the IPSec tunnel. The epdg then tunnels the packet to the visited Serving. The visited Serving then tunnels the packet to the. From the normal IP based routing takes place In the downlink direction, the packet for UE (HoA) arrives at the. The tunnels the packet based on the binding cache entry to the visited Serving. The visited Serving tunnels the packet based on the binding cache entry to the epdg. The epdg then tunnels the packet to the UE via proper IPsec tunnel 22

23 PMIPv6: an example scenario (I) UE E-UTRAN Data packets Serving Gateway HA Gateway Operator IP services (e.g. IMS, PSS,..) PBA S2b MAG PBU S2a epdg MAG Trusted non 3GPP access A Untrusted non 3GPP IP access 23

24 PMIPv6: an example scenario (II) E-UTRAN Serving Gateway HA Gateway Data packets Operator IP services (e.g. IMS, PSS,..) PMIP tunnel S2a S2b MAG epdg MAG Trusted non 3GPP access A Untrusted non 3GPP IP access Data packets UE 24

25 PMIPv6 in 3GPP vs. PMIPv6 in IETF The PMIPv6 usage scenarios foreseen for 3GPP SAE/LTE present some differences with respect to those in the scope of the IETF MIP6 WG PMIPv6 is used for inter-system handovers (i.e. handovers between 3GPP and accesses) PMIPv6 is used as a global mobility protocol PMIPv6 may be used in roaming scenarios, which means that the HA and the Proxy Mobility Agent may be located in different administrative domains in the roaming case there is the possibility to have a cascade of PMIPv6 tunnels (A Serving, Serving ) in this way there is a local anchor point in the visited domain, that can be used by the visited operator to enforce policies on UE s traffic the local anchor also simplifies the establishment of roaming agreements 25

26 Conclusions IETF protocols will be extensively used for 3GPP-non-3GPP mobility in UMTS Rel8 PMIPv6, DSMIPv6 and MIPv4 in FA mode Some open issues still need to be resolved/clarified mobility mode selection (PMIPv6, DSMIPv6 and MIPv4 in FA mode) multihoming (i.e. multiple interface) management simultaneous usage of multiple access technologies for load-sharing or performance optimization combined usage of PMIPv6 and DSMIPv6 in case the UE moves into an access network that does not support any mobility feature (e.g. domestic/public WiFi access) handover optimizations for tight interworking with mobile WiMAX and/or CDMA