Mobile IPv4 White Paper

HP-UX Mobile IPv4 White Paper 2
Mobile nodes were not considered when the Internet Protocol
(IPv4) was designed. Then and now, a node's IP address, which
indicates its point of attachment to the Internet, is assumed to
remain unchanged for the duration of a session.
MOBILTY FOR
INTERNET PROTOCOL
(IPv4)
Mobile IP, a standard proposed by the Internet Engineering Task
Force (IETF), was designed to solve this problem by allowing the
mobile node to use two IP addresses: a fixed Home Address and
a Care-of Address (COA) that changes at each new point of
attachment to the Internet.
How Mobile IP Works
Mobility Support for IPv4 defines a protocol that allows
transparent routing of IP datagrams to Mobile Nodes as they
move about from one domain to another on the Internet. When a
Mobile Node moves into a foreign network, its computing
activities are not disrupted. Instead, all the needed reconnection
occurs automatically and without user interaction.
Roles
The Role of the Mobile Node
A MN is responsible for detecting change in network
connectivity and acquiring a care-of address. It initiates the
process of informing its Home Agent of it current Care-of
Address. Mobile Nodes using colocated a Care-of Address also
needs to perform tunneling and encapsulation of packets.
The Role of the Foreign Agent
A Foreign Agent relays location updates and acknowledgments
between the Home Agent and Mobile Node. If it is also the Care-
of Address for the Mobile Node, the Foreign Agent forwards
encapsulated packets destined to the Mobile Node. The Foreign
Agent generally serves the Mobile Node as its default router.
The Role of the Home Agent
A Home Agent processes and coordinates mobility services for
the Mobile Node. The Home Agent receives location updates
from the Mobile Node, and acknowledges the updates with the
result. The Home Agent recives packets that arrive on the
network destined for a Mobile Node that it serves and tunnels
them to the Mobile Node’s Care-of Address.