If a mobile device moves to a new network and keeps the same IP address, the address will not reflect its new location therefore routers will be unable to route datagram to it correctly (or at all).

Alternatively, if a mobile device moves to a new network and gets allocated a new address, already established associations (FTP, etc) will be lost If the mobile host moves without changing its address, it will lose routing; but if it does change its address, it will lose connections !!

Key Component  : Mobile Host keeps its address of 128.6.5.30 as it moves from its Home Network to the Foreign Network.

 Mobile IP and Mobile IP Terminology

Mobile IP Terminology

Mobile Host: The device which has moved from its home network to a visiting network without changing its address

Home Agent:  A router on the home network which tunnels packets to the mobile host while it is away from home

Foreign Agent: A router on the foreign network which provides routing service to a mobile host all the while it is registered with the Foreign Agent

Correspondent Host:  A peer with which a mobile node is communicating – may be either stationary or mobile

Mobility Agent: Either a Home Agent or a Foreign Agent, Care-of Address,  A temporary address used by the mobile host while it is on a foreign network.

There are two types:

  1. Foreign Agent Care of Addresses: An IP address of a Foreign Agent which has an interface on the foreign network being visited by the Mobile Host
  2. Co-located Care of Address: An IP address temporarily assigned to the Mobile Host Itself

Tunneling:  A tunnel is the path followed by a first packet while it is encapsulated within the payload portion of a second packet

Home Address:  The original (normal) address of the mobile host.

Mobility Binding:  An association between a home address, care-of address and a registration lifetime