Mobile IP

Mobile IP is an Internet Engineering Task Force (IETF) standard communications Protocol (computing) that is designed to allow mobile device users to move from one network to another while maintaining their permanent IP address.

=Introduction=

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.

==Applications==

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.

In many applications, sudden changes in network and IP-address can cause problems. Examples of these applications include:

VPN

VoIP

Microsoft Office

databases

streaming media

=How Mobile IP Works=

In brief, Mobile IP routing works as follows. Packets destined to a mobile node are routed first to its home network -- a network identified by the network prefix of the mobile node s (permanent) home address. At the home network, the mobile node s home agent intercepts such packets and tunnels them to the mobile node s most recently reported care-of address. At the endpoint of the tunnel, the inner packets are decapsulated and delivered to the mobile node. In the reverse direction, packets sourced by mobile nodes are routed to their destination using standard IP routing mechanisms.

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.

==Future==

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.

==NetBIOS similarity==

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.

=External links=

IETF [http://www.ietf.org/]

Mobile IP Web Resources [http://computer.org/internet]

Protocols for Adaptive Mobile and Wireless Networking [http://www.monarch.cs.cmu.edu/]