Mobile IP is the IETF proposed standard solution for handling
terminal mobility among IP subnets and was designed to allow a
host to change its point of attachment transparently to an IP
network. Mobile IP works at the network layer, influencing the
routing of datagrams, and can easily handle mobility among different
media (LAN, WLAN, dial-up links, wireless channels, etc.). Mobile
IPv6 is a protocol being developed by the Mobile IP Working Group
(abbreviated as MIP WG) of the IETF (Internet Engineering Task
           The intention
of Mobile IPv6 is to provide a functionality for handling the
terminal, or node, mobility between IPv6 subnets. Thus, the protocol
was designed to allow a node to change its point of attachment
to the IP network such a way that the change does not affect the
addressability and reachability of the node. Mobile IP was originally
defined for IPv4, before IPv6 existed. MIPv6 is currently becoming
a standard due to inherent advantages of IPv6 over IPv4 and will
therefore be ready soon for adoption in 3G Mobile networks. Mobile
IPv6 is a highly feasible mechanism for implementing static IPv6
addressing for mobile terminals. Mobility signaling and security
features (IPsec) are integrated in the IPv6 protocol as header

The current version of IP (known as version 4 or IPv4) has not
changed substantially since RFC 791, which was published in 1981.
IPv4 has proven to be robust, and easily implemented and interoperable.
It has stood up to the test of scaling an internetwork to a global
utility the size of today’s Internet. This is a tribute to its
initial design.
However, the
initial design of IPv4 did not anticipate:

” The recent exponential growth of the Internet and the impending
exhaustion of the IPv4 address space 

Although the 32-bit address space of IPv4 allows for 4,294,967,296
addresses, previous and current allocation practices limit the
number of public IP addresses to a few hundred million. As a result,
IPv4 addresses have become relatively scarce, forcing some organizations
to use a Network Address Translator (NAT) to map a single public
IP address to multiple private IP addresses.

” The growth of the Internet and the ability of Internet
backbone routers to maintain large routing tables

Because of the way that IPv4 network IDs have been (and are currently)
allocated, there are routinely over 85,000 routes in the routing
tables of Internet backbone routers today.
” The need for simpler configuration
Most current
IPv4 implementations must be either manually configured or use
a stateful address configuration protocol such as Dynamic Host
Configuration Protocol (DHCP). With more computers and devices
using IP, there is a need for a simpler and more automatic configuration
of addresses and other configuration settings that do not rely
on the administration of a DHCP infrastructure.
” The
requirement for security at the IP level
Private communication over a public medium like the Internet requires
cryptographic services that protect the data being sent from being
viewed or modified in transit. Although a standard now exists
for providing security for IPv4 packets (known as Internet Protocol
Security, or IPSec), this standard is optional for IPv4 and proprietary
security solutions are prevalent.
” The need for better support for real-time delivery of data-also
called quality of service (QoS)