Santhosh Rajathayalan ( ) Senthil Kumar Sevugan ( )

Cellular TechnologyArchitectureData Mobility ProtocolAuthentication/Authorization GSM/GPRS Circuit Switched Voice, Packet Switched Data GPRS/Mobile IPHLR/HSS CDMA2000 1x-RTT Circuit Switched Voice, Packet Switched Data Mobile IPHLR/HSS CDMA2000 1x-EV-DOPacket Switched DataMobile IPHLR/HSS Mobile WiMAX Packet Switched Voice And Data Mobile IPAAA Server, RADIUS Cellular Networks

CDMA 2000 Network Architecture:

WiMAX Network Architecture:

Mobile IP was developed as a means for transparently dealing with problems of mobile users Enables hosts to stay connected to the Internet regardless of their location Enables hosts to be tracked without needing to change their IP address Requires no changes to software of non-mobile hosts/routers Requires addition of some infrastructure Requires no modifications to IP addresses or IP address format Supports security

Network Entities : Mobile Node (MN) The entity that may change its point of attachment from network to network in the Internet -Detects and registers with “best” FA Assigned a permanent IP called its home address to which other hosts send packets regardless of MN’s location Since this IP doesn’t change it can be used by long-lived applications as MN’s location changes. Home Agent (HA) This is router with additional functionality Located on home network of MN Does mobility binding of MN’s IP with its COA Forwards packets to appropriate network when MN is away

Network Entities : Foreign Agent (FA) Another router with enhanced functionality If MN is away from HA the it uses an FA to send/receive data to/from HA Advertises itself periodically Forward’s MN’s registration request Decapsulates messages for delivery to MN. Care-of-address (COA) Address which identifies MN’s current location Sent by FA to HA when MN attaches Usually the IP address of the FA Correspondent Node (CN) End host to which MN is corresponding (eg. a web server)

Messages Involved: Proxy Registration Request (PRRQ) The Registration Request message is sent by the Proxy Mobility Agent/MN to the Home Agent in order to set up a mobility binding entry for a mobile device. Proxy Registration Reply (PRRP) The Registration Reply message is sent by the Home Agent in response to the Proxy Registration Request received from the Proxy Mobility Agent/MN.

Types of Mobile IP Client Mobile IP Proxy Mobile IP RFC WiMAX Forum / 3GPP2 Proxy Mobile IPv4

Proxy Mobile IPv4 Provides mobility support without "touching" these Mobile Devices. Proxy Mobile IPv4 Client (PMIPv4 Client) is responsible for initiating and maintaining the Proxy Mobile IPv4 registration on behalf of the mobile device. It performs the Mobile IPv4 client function but is hosted in the network. In some cases, this function is collocated with the Foreign Agent(FA)

Proxy Registration During Initial Network Attachment Involves three stages: Authentication and authorization happen when the mobile device accesses the network. Mobile device attempts to obtain an IP address. This triggers Proxy Mobile IP, which assigns/authorizes the IP address. The mobile device configures its IP stack with the IP address and the obtained host configuration.

Proxy Registration During Initial Network Attachment Mobile device establishes a L2 (Layer 2) link with the base station and performs access Authentication/authorization with the AR(Access Router). AR contains the AAA client which exchanges AAA messages with the AAA infrastructure to perform authentication and authorization of the mobile device. The mobile device requests an IP address. The PMA sends a Proxy Registration Request (PRRQ) to the HA. The Home Agent sets up the mobility binding entry for the mobile device after assigning an IP address

Tables maintained in the Router: Visitor Table Maintained on FA serving an MN. Maps MN’s home address to its MAC address and HA address Mobility Binding Table Maintained on HA of MN. Maps MN’s Home Address with its current CoA.

Mobile IP functionality: Registering the Care-of Address Tunneling to the Care-of Address

Proxy Registration During Mobility Mobile device enters into a new network and establishes a L2 (Layer 2) link with the base station and performs access authentication/authorization with the AR(Access Router). The mobile device requests an IP address. Triggered by successful authentication, the PMA/FA sends a PRRQ to the HA. The Home Agent sets up the mobility binding entry for the mobile device with its new Care of Address(CoA). Now HA sends a PRRP message to New PMA, which then creates a Tunnel to forward data. Because the forwarding path is established between the new PMA and HA, the mobile device can receive or send IP packets using the Home Address.

Registration Revocation Triggered by the update of the mobility binding entry for a mobile device that has moved to a new AR. The HA may send a Registration Revocation to the old PMA (i.e., specifically to the Foreign Agent entity) in order to clean up unused resources in an expeditious manner. The old PMA removes the PMIPv4 states for the mobile device. The old PMA sends revocation acknowledgement to the HA.

Reverse Tunneling In the upstream direction if MS sends packets directly to the correspondent node, there is a mismatch. Now MS is in network with prefix Security devices (e.g., firewalls) may filter out these packets since it may mark them as illegal IP source addresses. This is to protect network to some types of denial of service attacks. Reverse tunneling addresses this issue by reversing the outgoing transmission as in the incoming route. MS sends the packets to FA, FA tunnels them to HA, and HA removes the tunnel and forwards the packet to the final destination.

. Appearance of Being at Home Network Mobile Node is not aware of its mobility and does not participate in handover signaling. The network entities emulate the home network to the mobile device attached on the network. From the mobile device’s perspective, it operates as if it were at the home network. The network is directing the mobile device’s traffic to and from its current location and will continue to do so when it moves to a new location

. Forwarding between Devices on Same PMA When the communication peers are both attached to the same PMA. The traffic between them should be routed via the HA without taking a local shortcut on the PMA. This ensures that data-traffic enforcement at the HA is not bypassed.

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