Mobile IP is an Internet Engineering Task Force (IETF) standard communications protocol that is designed to allow mobile device users to move from one network to another while maintaining their permanent IP address. Mobile IP is described in IETF RFC 3344 (which obsoletes RFC 3220 and RFC 2002). The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards, in particular, those of the TCP/IP protocol suite. ...
In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. ...
Mobile IP provides an efficient, scalable mechanism for node mobility within the Internet. Using Mobile IP, nodes may change their point-of-attachment to the Internet without changing their IP address. This allows them to maintain transport and higher-layer connections while moving. Node mobility is realized without the need to propagate host-specific routes throughout the Internet routing fabric.
Mobile IP is most often found in wireless WAN environments where users need to carry their mobile devices across multiple LANs with different IP addresses. It may also be used in 3G networks to provide transparency when internet users migrate between cellular towers. 3G (or 3-G) is short for third-generation mobile telephone technology. ...
In many applications, sudden changes in network and IP-address can cause problems. Examples of these applications include:
- Microsoft Office
- streaming media
A Virtual Private Network, or VPN, is a private communications network usually used within a company, or by several different companies or organizations, communicating over a public network. ...
IP Telephony, also called Internet telephony, is the technology that makes it possible to have a telephone conversation over the Internet or a dedicated Internet Protocol (IP) network instead of dedicated voice transmission lines. ...
How Mobile IP Works
In brief, Mobile IP works as follows. A mobile node can have two addresses - a permanent home address and a care-of address which is associated with the network the mobile node is visiting. There are two kinds of entities in Mobile IP -
- home agents store information about mobile nodes whose permanent address is in the home agent's network.
- foreign agents store information about mobile nodes visiting its network. Foreign agents also advertise care-of addresses which are used by Mobile IP.
A node wanting to communicate with the mobile node uses the home address of the mobile node to send packets. These packets are intercepted by the home agent which uses a table and tunnels the packets to the mobile's node care-of address with a new IP header, preserving the original IP header. The packets are decapsulated at the end of the tunnel to remove the added IP header, and delivered to the mobile node.
The Mobile IP protocol defines the following:
- an authenticated registration procedure by which a mobile node informs its home agent(s) of its care-of address(es);
- an extension to ICMP Router Discovery which allows mobile nodes to discover prospective home agents and foreign agents; and
- the rules for routing packets to and from mobile nodes, including the specification of one mandatory tunneling mechanism and several optional tunneling mechanisms.
Enhancements to the Mobile IP technique, such as Mobile IPv6 and Hierarchical Mobile IPv6 (HMIPv6), are being developed to improve mobile communications in certain circumstances by making the processes more secure and more efficient.
Readers may be intrigued to know that, aside from the authentication, Mobile IP is literally concept-for-concept identical to NetBIOS in combination with the Microsoft Network Neighborhood services. Readers may also be surprised to know that, despite the conceptual similarity, at the time that an analysis was done (January 2002) no reference to RFCs 1001 and 1002, nor to the Microsoft Network Neighborhood, could be found in any of the Mobile IP RFCs or Draft RFCs. NetBIOS is an acronym for Network Basic Input/Output System. ...
- Mobile IP Web Resources 
- Protocols for Adaptive Mobile and Wireless Networking 
- IP Mobility Support for IPv4
- Mobile IPv6 - A short Introduction  (PDF)