Mobile IP Networks

Mobility is a trend that is increasingly growing and becoming popular across businesses and enterprises. With the advent of laptops, smart phones and tablets, mobility is an important factor for businesses when deciding the appropriate communication system. There is also an increase in the use of virtual offices, and business workers are now able to be productive even when not inside the office.

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Image source highteck.net

Mobile IP requirements

Mobile IP allows a node to change its point of connection to the Internet without the need to change the IP address. This is important as this facilitates continuous and seamless application-level connectivity as the node moves from one location to another.

A solution to the problem that this poses involves protocol extensions wherein packets that are targeted to a mobile host are sent to the home network and then passed to a static node called a home agent. The mobile host registers the original location with the home agent. The home agent is then responsible for forwarding the packets to the host.

If the mobile host is attached to its home network, the process would be plan IP forwarding. The process is different if the host is moving. Packets must then be tunneled across the Internet to a care-of address where the host registers the attachment to a foreign agent. The packets are then forwarded to the mobile host.

While mobile IP can be used to address issues with IP mobility, it is best used within wireless LANs. Mobile phone networks are also better served by linklayer procedures. An alternative to this solution is to use source routing within IP. This technology however is fairly new and may not be supported by older networks.

Extending Protocols

To allow the mobile node to register with either the home agent or a remote foreign agent, specific protocol exchanges are necessary. A further registration process is also needed once the mobile node is registered with a foreign agent.

Through extensions to the ICMP router discovery process, mobile nodes discover available home and foreign agents. The agents, be they home or foreign, advertise their mobile IP capabilities through new TLVs, which follow the router advertisement in an ICMP Router Advertisement Message.

Security Issues and Concerns

Mobile IP standards mandate the use of strong and heavy authentication cryptography for the registration process between the home agents and a mobile node. This is because it is the most vulnerable part of the mobile IP process. If intercepted, it can cause the interception or diversion of all traffic sent from the home agent. Authentication can also be used between the mobile node and foreign agent and vice versa.

Encryption on the data exchanged between hosts participating in mobile IP can also be done. There are three models that may be used. The first one is where the source of the data encrypts it and then sends it through the home agents and then to the mobile node, which decrypts the data.

The second model is where the home agents choose whether to encrypt the data according to whether the mobile node is near or away from the home agent. In the third model, IPsec is used as the tunneling protocol between the home agent and the foreign agent and the mobile node does not need to have encryption or decryption capabilities.

Michelle Patterson helps companies understand and adopt new technologies in all aspects of their operations. She is currently working on new communication technologies that are promising a paradigm shift.

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