Computer Network Laboratory Group 5
˙The Principles and Applications of Mobile IP.
1.What is Mobile IP:
Each mobile node is always identified by its home address, regardless of its current point of attachment to the Internet. While situated away from its home, a mobile node is also associated with a care-of address, which provides information about the mobile node's current location. The packets addressed to a mobile node's home address are transparently routed to its care-of address. The protocol enables nodes to cache the binding of a mobile node's home address with its care-of address, and to then send any packets destined for the mobile node directly to it at this care-of address.
The following is a diagram that gives the ideas of mobile IP.
1.The Mobile Node (MN) travels to a foreign network and gets a new care-of-address.
2.The MN performs a binding update to its Home Agent (HA) (the new care-of-address gets registered at HA). HA sends a binding acknowledgement to MN.
3.A Correspondent Node (CN) wants to contact the MN. The HA intercepts packets destined to the MN.
4.The HA then tunnels all packets to the MN from the CN using MN's care-of-address.
5.When the MN answers the CN, it may use its current care-of-address (and perform a binding to the CN) and communicate with the CN directly (“route optimization”) or it can tunnel all its packets through the HA.
2.Why Mobile IP:
Mobile IP is targeted to the users who are mobile and need to work in a flexible manner - in the office, on the road, at customer premises, or at home.
There are numerous applications that do not cope well with network changes. In general, deploying a Mobile IP based solution ensures that all your applications will work properly in a mobile environment. Instead of building this function in the application, the underlying Mobile IP layer solves this problem once and for all. There are several examples of applications where sudden changes in network and IP-address can cause problems. The most common ones are listed below.
Remote Access VPNs:
Remote access VPNs(Virtual Private Network), based on IPSec technology, are very sensitive to IP-address changes. Mobile IP solution is compatible with all the major VPN solutions on the market.
Microsoft Office and Windows:
If a user edits a file on a server while changing networks, the file will be blocked on the server and cause problems.
Any client-server application based on ODBC(Open Database Connectivity) drivers or something like that will fail if the user changes IP-address while working.
Voice over IP:
Voice applications, which are becoming more and more popular on wireless networks, are typical examples of session driven applications. Without Mobile IP, the user has to restart the conversation every time he moves between networks or subnets.