What is Mobile IP?

Hi qaisarpk1,

I am assuming Mobile IP asked here is Mobile Internet Protocol.

Mobile IP is an extension to the Internet Protocol proposed by IETF(Internet Engineering Task Force).

Now question is what is so special in this protocol that other protocols like TCP/IP don't have right?
A: IP requires the location of any host connected to the Internet to be uniquely identified by an assigned IP address. Now it causes problems in mobility, because when a host moves from one physical location to another physical location, it has to change its IP address. But as per these higher level protocols require IP address of a host to be fixed for identifying connections. So comes Mobile IP for rescue.It enables mobile computers to stay connected to the Internet regardless of their location and without changing their IP address. This is the thing special in this protocol. In other words we can simply say Mobile IP is a standard protocol that build on Internet Protocol by making mobility transparent to applications and higher level protocols like TCP.

Now question that might be arousing is how this protocol works in actual?
A: In brief, I would say - This protocol allows each mobile node to have two IP addresses and then transparently maintaining the binding between the two addresses. One of the IP address is the permanent home address that is assigned at the home network and other is care-of-address that represents the current(or mobile) location of the host.

Now next question that might be troubling you would have been what is this care-of-address?
A: care-of-address is the IP address of the mobile node's current point of attachment. This address is assigned to the host by a Foreign Agent who is actually the home agent of current area in which mobile node is roaming.

Real life examples you can see around are PDAs, handhelds , digital cellular phones and other such wireless devices offering IP connectivity.

Hope this much information may be of some use to it right now. If you understood this much then on demand I can put more light on the whole process of this mobile way of networking. Others feel free to correct if any wrong information shared.

Thanks !

to add further, there are two versions of MIP.
One being IPV4 and IPV6.
Bascially, according to the OSI layer model, its only IP address which remains common for the higher layers like transport layer using TCP and UDP sessions and the lower layers like MAC which implement 802.11 protocols.
TCP - UDP
IP
802.11

hence, its more easy to use IP address while routing thorugh heterogenous networks.
to add to what sookie mentioned there is alreasy MIPv4 version gogin on,the importance of IPv6 being, seamless handofff from one network to another.
Though current hand offs happen usinf DHCP and SIp protocols, and since the transport layer uses TCP sessions, when you move from one network to another , you need to establish new session which will break youe TCP session . to avoid this breakage during hand off IPV6 had few interesting developments coming down.