Mobile IP

Introduction

Mobile IP is the underlying technology for support of various mobile data and wireless networking applications. For example, GPRS depends on mobile IP to enable the relay of messages to a GPRS phone via the SGSN from the GGSN without the sending needing to know the serving node IP address.ccess

The Impetus for Mobile IP

With the advent of packet based mobile data applications and the increase of wireless computing, there is a corresponding need for the ability for seamless communication between the mobile node device and the packet data network (PDN) such as the Internet.

Mobile IP Definitions

Mobile Node: A device capable of performing network roaming
Home Agent: A router on the home network which serves as the a point for communications with the mobile node.

Foreign Agent: A router that functions as the mobile node's point of attachment when it travels to the foreign network.

Care of Address: Termination point of the tunnel toward the mobile node when it is not in the home network.

Correspondent Node: The device that the mobile node is communicating with such as a web server

Mobile IP in Operation

To accomplish this, mobile IP established the visited network as a foreign node and the home network as the home node. Mobile IP uses a tunneling protocol to allow messages from the PDN to be directed to the mobile node's IP address. This is accomplished by way of routing messages to the foreign node for delivery via tunneling the original IP address inside a packet destined for the temporary IP address assigned to the mobile node by the foreign node. The Home Agent and Foreign Agent continuously advertise their services on the network through an Agent Discovery process, enabling the Home Agent to recognize when a new Foreign Agent is aquired and allowing the Mobile Node to register a new Care of Address.

This method allows for seamless communications between the mobile node and applications residing on the PDN, allowing for seamless, always-on connectivity for mobile data applications and wireless computing.

Mobile IP enabled Applications

Mobile IP technology is embedded in the functionality of packet equipment for 2.5G and 3G. In addition, mobile IP enables advanced applications such as unified messaging.

Additional Resources:Books about: IP-based Communication