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MAC Layer_ MUX Layer_ and RLP

VIEWS: 2 PAGES: 43

									3G Packet Data Architecture




                     3G Packet Data Architecture
                          -- An Overview --


                              Parviz Yegani
                              June 17, 1999




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3G Packet Data Architecture



                              Outline
     •    TSG-P/TR-45.6 Overview
     •    Requirements
     •    Protocol Options
     •    Functional Architecture
     •    Logical Architecture
     •    Protocol Architecture
     •    IMT-2000 Logical Interfaces
     •    R-P Interface Requirements
     •    R-P Interface Architecture Choices
     •    Service Examples
     •    Acronyms
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3G Packet Data Architecture



                            TSG-P/TR-45.6 Overview
     • Scope: Define IMT-2000 network architectures to
       support packet data services.
     • TR45.6 formed in August 98 and chaired by Mark
       Munson (GTE).
     • TR45.6 work will eventually be handed over to
       TSG-P (formed in January 99)
     • Driven by CDMA community.
     • Deliverables: Architecture document by 2Q99.
     • Based on IETF protocols (e.g. Mobile IP).




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3G Packet Data Architecture



                                 Requirements
     • Access to public Internet or private networks from home IMT-2000
       network.
     • Access to public Internet or private networks from visited IMT-
       2000 network.
              – Direct access without going through home IMT-2000 network.
              – Indirect access via home IMT-2000 network.
     • Support dynamic and static IP address configuration.
              – For Mobile IP, MS’s home address and home agent may be
                dynamically assigned.
     • Support public and private IP address configuration.
     • Support simultaneous IP addresses in the MS.
     • Provide Authentication Authorization Accounting (AAA) functions.
              – AAA functions for packet data services are indexed by NAI (e.g.
                yegani@ericsson.com).




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3G Packet Data Architecture



                            Protocol Options - Simple IP
     • MS’s address is dynamically assigned by PDSN
       via IPCP.
     • Limited mobility within PDSN serving area.
     • When crossing PDSN boundary, MS’s address
       changes, affecting MS’s applications.




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3G Packet Data Architecture



             Protocol Options - Basic Mobile IP
     • Same as CDG’s Mobile IP Implementation
       Guideline (based on the current version of RFC
       2002).
     • MS’s home address and HA are fixed.
     • Registration authentication is required between
       MS and HA.
     • If FA and HA are in different administrative
       domains, registration authentication is required
       between FA and HA.
     • A shared secret is needed for two entities to
       authenticate each other. Each shared secret is
       provisioned manually.

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3G Packet Data Architecture



     Protocol Options - Enhanced Mobile IP
     • Include new extensions (e.g. NAI Extension) in the next version of
       RFC 2002.
     • Use DIAMETER for AAA services.
              – Each MS has one shared secret with an AAA server.
              – Each mobility agent (FA or HA) has one shared secret with an AAA
                server.
              – AAA server of each different administrative domain has one shared
                secret with a broker AAA server.
              – This removes the problem of meshing shared secrets among mobility
                agents and MSs.
     • MS’s home address and HA may be dynamically assigned.
     • Charles Perkins and Pat Calhoun are leading this development
       effort in IETF.




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3G Packet Data Architecture



                            Functional Architecture


                              LMF                Packe t
                                                M obility
                                                Function
                   MCF        PCF         PRF               HA



                              RRC                AAA




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3G Packet Data Architecture



                            Home Agent (HA)
        Functions
              Responsible for authentication of packet data service for the
               mobile client;
              Redirecting packets to the Foreign Agent;
              Optionally, establish, maintain, and terminate secure tunnel to the
               Foreign Agent;
              Receives provisioning from the AAAF for users;
              Optionally, assigns dynamic IP address;
              Verifying mobility requests from the mobile client.




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3G Packet Data Architecture



              Packet Routing Function (PRF 1 of 3)

    Functions
          Establish maintain, and terminate link layer to the mobile
           client;
          Assign IP address for Simple IP, the dynamic address
           may be chosen by the PRF or AAA
          As Mobile IP Foreign Agent, advertise as a foreign agent
           in the mobile network;
          Initiate the authentication, authorization and accounting
           for the mobile client packet data service to the AAA;
          Map NAI and Mobile Client IP address to the Mobile
           Identifier and unique identifier used to communicate with
           the PCF;


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3G Packet Data Architecture



              Packet Routing Function (PRF 2 of 3)

    Functions (continued)
         In Version 2, optionally, interact with a previous Packet Routing
          Function to obtain:
         Address of the Home Agent Function for the mobile client;
         Obtain security information for authentication;
         QoS and packet service parameters for the mobile client;
         Optionally, establish, maintain, and terminate secure tunnel to the
          Home Agent;
         Interacts with PCF to establish, maintain and terminate the layer 2
          connection
         Receives service parameters from AAAF for mobile client;




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3G Packet Data Architecture



              Packet Routing Function (PRF 3 of 3)

    Functions (continued)
         Record usage data, receive accounting information from the PCF,
          correlate to generate the accounting information, and relay the
          correlated information to the AAAF.
         Routes packets to external packet data networks or to HA in the case
          of tunneling to the HA .
         Interact with the serving PCF and the target PCF to maintain PPP
          connection to the mobile client as part of the hard handover




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3G Packet Data Architecture



               Packet Control Function (PCF 1 of 2)

    Functions
         Interacts with the LMF for updating routing information and packet
          data services profiles of mobile stations in the case of hard handover
          and dormant handover
         Interact with the PCF to receive packet data service profile of mobile
          station such as QoS
         Maintain state of reachability for packet service between the radio
          network and the mobile station;
         Buffers packets arriving from the PRF, when radio resources are not
          in place or are insufficient to support the flow from the PRF.




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3G Packet Data Architecture



               Packet Control Function (PCF 2 of 2)

    Functions (continued)
         Communicates with the RRC to request reachability to relay the
          packets to the mobile station;
         Relays packets between the mobile station and PRF;
         As part of the hard handover to another RRC, forwards serving PCF
          information to the target PCF to re-establish the packet connection to
          the PRF
         Maps IMSI and connection reference to a unique link layer identifier
          used to communicate with the PRF
         Collect and send accounting information (e.g. identification to the
          location) to the PRF
        




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3G Packet Data Architecture



              Authentication, Authorization and
                 Accounting Function (AAA)
    Functions
              Interact with the PRF to provide a secure mechanism to authorize,
               authenticate and perform accounting for the mobile client;
              Interact between networks to provide a secure mechanism to
               authorize, authenticate, and perform accounting for the mobile
               client;
              Interact with the HA to provide a secure mechanism to authorize,
               authenticate, and perform accounting for the mobile client sending
               a registration request;
              For dynamic Home Agent assignment, dynamically identify a HA
               and assign a user on that HA;
              Maintain and provide a user profile and QoS information to the PRF
              Optionally, assign dynamic IP address for Mobile IP and/or Simple
               IP services


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3G Packet Data Architecture



              Radio Resource Control Function
                          (RRC)
    Functions
                 Establishes, maintains and terminates radio
                  resources for the exchange of packets between
                  the mobile station and the PCF.
                 Broadcast packet zone ID in the system overhead
                  message so that a mobile station can detect
                  packet zone ID




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3G Packet Data Architecture



                        Mobile Client Function (MCF)

    Functions
         Requests appropriate radio resources from the network for the
          exchange of packets;
         Maintains knowledge of status of radio resources for packet service
          between the mobile station and the radio network (e.g., active,
          standby, dormant);
         Buffers packets from the mobile client when radio resources are not
          in place or are insufficient to support the flow to the network.
         Receives the packet zone ID information from the system overhead
          message, and performs Mobile IP registration when the packet zone
          ID changes.




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3G Packet Data Architecture



       Location Management Function (LMF)

    Functions
          Responsible for location and packet service profile
           management for the mobile station
          Interacts with the target PCF for updating routing
           information and packet data service profile of a mobile
           station for the dormant handover case.
          Optionally interacts with the other LMF for updating
           packet data service profile of the mobile station for the
           dormant handover case.




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3G Packet Data Architecture



                                        Logical Architecture
                                                                            SS7
                                                                   VLR     Network        HLR

                                                                                      Home Access
                                                                                     Provider Network



                                                                                          Home
                                                               Visited
                                                                                          AAA
                                                                AAA
                                                                                           Home IP
                                                                                           Network


                                                                                            AAA
                                                                             IP            Server
                                                       R-P                 Network
                                                       Interface                          AAA Broker
                                                                                            Network

                            Mobile Station                          PDSN
                                             Access Network
                              Mobile            RRC                PRF
                              Client            PCF                FA
                                                                                           HA
                                                 Visited Access
                                                Provider Network                         Home ISP
                                                                                      Private Network
                                                                                      Visited Provider
                                                                                      Home Provider




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3G Packet Data Architecture



                                      Protocol Architecture


                            MIP                                    MIP               MIP

                            UDP                                   UDP               UDP

                             IP                                                IP
                                                             IP          IP                IP       IP
                            PPP/            L2             PPP/
                            HDLC           Relay           HDLC
                                                                      Link     Link         Link    Link
                             LAC                                     Layer    Layer        Layer   Layer
                                        LAC         Link    Link
                            MAC        MAC         Layer   Layer

                            Airlink    Airlink   PHYS      PHYS      PHYS     PHYS       PHYS      PHYS


                            Mobile                                                                 End
                                          RAN                 PDSN                  HA
                            Station                                                                Host




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3G Packet Data Architecture



                            IMT-2000 Reference Model
                               (Public Internet Access with Simple IP)

                                                                        SS7
                                                               VLR     Network        HLR

                                                                                  Home Access
                                                                                 Provider Network



                                                                                      Home
                                                           Visited
                                                                                      AAA
                                                            AAA
                                                                                       Home IP
                                                                                       Network


                                                                                        AAA
                                                                         IP            Server
                                                   R-P                 Network
                                                   Interface                          AAA Broker
                                                                                        Network

                        Mobile Station                          PDSN
                                         Access Network




                                             Visited Access
                                            Provider Network




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3G Packet Data Architecture



                   IMT-2000 Logical Interfaces (1 of 3)
               (Public Internet Access for HA in the serving IMT-2000 network with Mobile IP     )

                                                  VLR                             HLR




                                                  Visited          Broker       Home
                                                   AAA              AAA         AAA
                                                                 AAA Broker
                                                                   Network




                                      R-P
                                      Interface

     Mobile Station                               PDSN                           HA
                            Access Network
                                                                               Home Access
                                                                              Provider Network
                                               Visited Access
                                              Provider Network

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3G Packet Data Architecture



                   IMT-2000 Logical Interfaces (2 of 3)
       (Public Internet Access for HA assigned in the serving IMT-2000 network with Mobile IP              )
                                                  VLR                                    HLR

                                                                                     Home Access
                                                                                    Provider Network




                                                  Visited             Broker            Home
                                                   AAA                 AAA              AAA
                                                                    AAA Broker      Home Access Provider
                                                                      Network       Home ISP
                                                                                    Private Network




                                      R-P
                                      Interface

       Mobile Station                             PDSN               HA
                            Access Network
                                                                  Visited Access
                                                                 Provider Network


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3G Packet Data Architecture



                   IMT-2000 Logical Interfaces (3 of 3)
                        (Public Internet Access for External Network Access with Mobile IP   )

                                                     VLR             HLR




                                                 Diameter          Diameter            Diameter
                                                  Serv er           Serv er             Serv er


                                                                 Home Netw ork


                                    R-P Interf ace                  IPsec



    Mobile Station                                   PDSN                        Firew all       Home
                              RN
                                                                                                 Agent
                              Visited Netw ork                                      Target Netw ork




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3G Packet Data Architecture



                  R-P Interface Requirements(1 of 3)
      RN-PDSN (R-P) uses a unique link layer ID for each session.
      The PDSN maintains the association between the IP/NAI and the
       link ID.
      The link ID should be such that it can easily be recovered after a
       handoff from an old RN to a new RN.
      Handoff information from one RN to another is exchanged
       across this interface
      No reachability information (e.g., whether mobile is
       dormant/active) is communicated across this interface.
      The link layer association is maintained even when mobile is
       dormant. This facilitates reconnection when mobile comes out of
       dormancy.
      The link protocol shall be able to efficiently transport the widely
       ranging data rates expected for 3G packet service. It should
       minimize any additional latency.



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3G Packet Data Architecture



                  R-P Interface Requirements(2 of 3)
      Congestion control and security mechanisms in the link protocol
       shall be optional.
      ATM, frame relay, and tunneled IP networks are suitable link layer
       subnetworks for this interface.
      Packet data accounting information is communicated over this
       interface.
      The RN shall establish a link connection to initiate a packet data
       session.
      The RN or PDSN may tear down a link connection to close down a
       packet data session.
      The R-P interface in Version 1 shall be capable of transporting
       PPP frames, and shall identify the QoS of each PPP frame. The R-
       P interface in Version 1 applies to mobile access using a PPP data
       link layer.




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3G Packet Data Architecture



                  R-P Interface Requirements(3 of 3)
      The R-P interface in Version 2 shall be capable of transporting
       level 3 IP packets, and shall identify the QoS of each packet. The
       R-P interface in Version 2 applies to mobile access using a
       simplified data link layer. This requirement is under study

     • Note: PPP is supported over the R-P interface in Version 2.




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3G Packet Data Architecture


          Architecture Options for the R-P Interface


                                                                              PDSN
                                                                        PRF
                                         PDSN
                                    PRF
                                                                              A-BSC

                                                                    PCF               RRC
                             BSC                      BSC

                       PCF         RRC          PCF         RRC   BSC                       BSC

                                                                        RRC                       RRC
                                     Direct Connect                             2-Tier




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3G Packet Data Architecture



                            Direct-Connect Architecture
    Advantages
    • Defines an interface between the PDSN and the BSC
    • Keeps most knowledge of the radio access network out of the
      PDSN
    • A simple solution that allows to progress work on the standards
      while solving the most common problem (PDSN to BSC
      connectivity)
    • This solution can be extended to address the Ax interface as
      needed
    • The solution minimizes new interfaces and elements
    • The solution does not penalize either large or small BS vendors.
    Disadvantages
    • A packet zone spans multiple BSCs which may cause data loss
      (location tracking is not done on at least BSC boundaries)



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3G Packet Data Architecture



                            2-Tier Architecture
     Advantages
     • Defines an interface between the PCF (or Anchor BSC) and the
       BSC
     • Provides the ability to have small BSC systems and thus require
       the centralized PCF to cover multiple BSCS
     • Minimizes the signaling traffic caused by packet zone boundary
       crossing by allowing a single packet zone to span multiple BSCs




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3G Packet Data Architecture



                             Service Examples
     • Simple IP
              – Example 1: Private network access from home IMT-2000 network.
              – Example 2: Public Internet access from visited IMT-2000 network.
     • Basic Mobile IP
              – Example 3: Public Internet access from home IMT-2000 network.
              – Example 4: Public Internet access from visited IMT-2000 network.
     • Enhanced Mobile IP
              – Example 5: Private network access from IMT-2000 network.




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3G Packet Data Architecture


                            Example 1 - Private Network Access
                                 from Home Network via Simple IP

    • MS is assigned with an IP address from PDSN via IPCP.
    • MS may use Mobile IP collocated COA for private network access.
            –    MS uses the IWF-assigned address as the collocated COA.
            –    HA is in the private network.
            –    Mobile-IP tunnel is between MS and HA.
            –    MS may use end-to-end IP Security.
            –    There is no Mobile-IP infrastructure in home IMT-2000 network.
    • MS may use L2TP for private network access.
            –    MS uses the IWF-assigned address as the LAC address.
            –    LNS is in the private network.
            –    L2TP tunnel is between MS and LNS.
            –    There is no L2TP infrastructure in home IM-2000 network.
    • MS may use other end-to-end VPN schemes (e.g. PPTP) for private
      network access.


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3G Packet Data Architecture


                            Example 2 - Public Internet Access
                             from Visited Network via Simple IP (1 of 2)

    • This is an example of ISP roaming, where the MS’s home ISP is an
      IMT-2000 network or a wire-line network.
    • MS requests packet data service in visited IMT-2000 network.
    • MS’s airlink access is authenticated via VLR/HLR.
    • MS initiates a PPP session with PDSN.
    • MS is authenticated by home ISP via CHAP and proxy RADIUS.
            – IWF sends a CHAP Challenge to MS.
            – MS replies a CHAP Response containing hashed secrets and NAI.
            – IWF forwards hashed secrets and NAI to visited RADIUS server.
            – Based on NAI, visited RADIUS server sends hashed secrets and NAI to
              home RADIUS server.
            – Home RADIUS server uses NAI to identify the user and authenticates
              the hashed secrets.
    • MS is assigned with an IP address from PDSN via IPCP.



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3G Packet Data Architecture


                            Example 2 - Public Internet Access
                              from Visited Network via Simple IP (2 of 2)
                                                                          Visited       Home
      MS                    BS/MSC               VLR/HLR        IWF    RADIUS Server RADIUS Server


           Service Request




                 Airlink Access Authentication




                                     PPP LCP




                                     PPP CHAP


                                                                      User Authentication


                                     PPP IPCP




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3G Packet Data Architecture


                            Example 3 - Public Internet Access
                            from Home Network via Basic Mobile IP (1 of 2)

     •    MS requests packet data service.
     •    MS’s airlink access is authenticated via HLR.
     •    MS initiates a PPP session with IWF.
     •    MS performs Mobile-IP Agent Discovery.
              – MS receives Agent Advertisement from IWF/FA.
              – Agent Advertisement contains FA’s COA.
     • If FA’s COA is new, MS performs Mobile-IP Registration:
              – MS sends a Registration Request (home address, HA address, MS-HA
                authentication extension, etc.) to the FA.
              – FA forwards the Registration Request to HA.
              – HA authenticates the MS, binds MS’s home address to FA’s COA, and
                sends Registration Reply (lifetime, etc.) to the FA.
              – FA adds the MS to visitor list and forwards the Registration Reply to
                the MS.
              – MS authenticates the HA.
     • If FA’s COA is old, MS doesn’t perform Mobile-IP Registration.
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3G Packet Data Architecture


                            Example 3 - Public Internet Access
                             from Home Network via Basic Mobile IP (2 of 2)


                                                       Home IMT-2000 Network

                            MS             BS/MSC                 HLR            IWF/FA   HA


                             Service Request




                                 Airlink Access Authentication




                                                       PPP




                                            Mobile-IP Agent Discovery




                                                        Mobile-IP Registration

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3G Packet Data Architecture


                            Example 4 - Public Internet Access
                              from Visited Network via Basic Mobile IP

     • If roaming agreement exists between home and visited IMT-2000
       networks, MS may access to public Internet from visited IMT-2000
       network via home IMT-2000 network.
              – HA is in home IMT-2000 network, because MS’s home address and HA
                are fixed.
              – FA is in visited IMT-2000 network.
              – FA-HA authentication is required. FA-HA shared secrets are manually
                provisioned. This is manageable if the FA-HA mesh is small and
                static.
     • Disadvantages:
              – The provision of FA-HA authentication will be unmanageable if the
                number of roaming agreements increases and FA-HA mesh becomes
                more dynamic.
              – Because MS’s HA is fixed, Basic Mobile IP does not allow MS to
                access to public Internet directly from visited IMT-2000 network
                without going through home IMT-2000 network.



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3G Packet Data Architecture


                            Example 5 - Private Network Access
                               via Enhanced Mobile IP (1 of 4)

                                    Proxy
                                                                   AMA                         HAA
                                    AMA
                                    AMR                          Proxy AMR                     HAR

                     FA                                                                                   HA
                                            Visited AAA Server               Home AAA Server

                                                                                        Private Network
                                      Registration
                                       Request
                            Registration
                              Reply
                                      Radio Access
                                         Network




                                                     MS
                             IMT-2000 Network

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3G Packet Data Architecture


                            Example 5 - Private Network Access
                               via Enhanced Mobile IP (2 of 4)
     • MS
              – Receives Agent Advertisement from FA.
              – Sends Registration Request to FA.
              – Registration Request includes NAI, home address = 0, HA address = 0,
                hashed secret between MS and home AAA server, etc..
     • FA
              – Sends AAA-MN-Request (AMR) to visited AAA server.
              – AMR includes Registration Request, hashed secret between FA and
                visited AAA server, etc..
     • Visited AAA server
              – Authenticates the AMR.
              – Sends Proxy AMR to home AAA server, based on MS’s NAI.
              – Proxy AMR includes Registration Request, hashed secret between
                visited and home AAA servers, etc..




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3G Packet Data Architecture


                            Example 5 - Private Network Access
                               via Enhanced Mobile IP (3 of 4)
     • Home AAA server
              –   Authenticates the Proxy AMR
              –   Authenticates the Registration Request.
              –   Assigns a HA to the MS, because MS’s HA address is zero.
              –   Sends Home-Agent-Request (HAR) to the chosen HA.
              –   HAR includes Registration Request, hashed secret between home
                  AAA server and HA, etc..
     • HA
              – Authenticates the HAR.
              – Assigns a home address to the MS, because MS’s home address is
                zero. The home address is included in the Registration Reply.
              – Binds the MS’s home address to the FA’s COA.
              – Sends Home-Agent-Answer (HAA) to home AAA server.
              – HAA includes Registration Reply, hashed secret between HA and
                home AAA server, etc..



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3G Packet Data Architecture


                            Example 5 - Private Network Access
                               via Enhanced Mobile IP (4 of 4)
     • Home AAA server
              – Authenticates the HAA.
              – Include the hashed secret between Home AAA server and MS in the
                Registration Reply.
              – Sends AAA-MN-Answer (AMA) to visited AAA server.
              – AMA includes Registration Reply, hashed secret between home and
                visited AAA servers, etc..
     • Visited AAA server
              – Authenticates the AMA.
              – Sends Proxy AMA to FA.
              – Proxy AMA includes Registration Reply, hashed secret between
                visited AAA server and FA, etc..
     • FA
              – Authenticates the Proxy AMA.
              – Adds the MS to the visitor list.
              – Sends Registration Reply to the MS.
     • MS authenticates the Registration Reply.
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3G Packet Data Architecture



                                 Acronyms (1 of 2)
     •    AAA               Authentication Authorization Accounting
     •    AMA               AAA-MN-Answer
     •    AMR               AAA-MN-Request
     •    CDG               CDMA Development Group
     •    CHAP              Challenge Handshake Authentication Protocol
     •    COA               Care-Of Address
     •    FA                Foreign Agent
     •    HA                Home Agent
     •    HAA               Home Agent Answer
     •    HAR               Home Agent Request
     •    HLR               Home Location Register
     •    IETF              Internet Engineering Task Force
     •    IPCP              Internet Protocol Control Protocol
     •    ISP               Internet Service Provider
     •    IWF               Inter-Working Function
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3G Packet Data Architecture



                                 Acronyms (2 of 2)
     •    L2TP              Level-2 Tunneling Protocol
     •    LAC               L2TP Access Concentrator
     •    LCP               Link Control Protocol
     •    LMF               Location Management Function
     •    LNS               L2TP Network Server
     •    MS                Mobile Station
     •    NAI               Network Address Identifier
     •    PCF               Packet Control Function
     •    PDSN              Packet Data Service Node
     •    PPP               Point-to-Point Protocol
     •    PPTP              Point-to-Point Tunneling Protocol
     •    PRF               Packet Routing Function
     •    RADIUS            Remote Authentication Dial-In User Service
     •    VPN               Virtual Private Network
     •    VLR               Visited Location Register
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