mobile internet devices

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INTRODUCTION
Mobility support for internet devices is quite more important. Today we have to face several problems that make difficult to use mobile internet devices. The problem is based in the routing mechanisms which are used in the internet. Ip address defines a kind of topological relation between the linked computers.
Today’s versions of internet protocols assume implicit that any node has always the same point of attachment to the internet. Additionally the nodes ip address identifies the page link on which the node resides. [1] If a node moves without changing its ip address, there is no information in its network address about the new point of attachment to the internet. Existing routing protocols thus not able to deliver datagram correctly.


TERMINOLOGY
Binding
The association of the home address of a mobile node with a care of address for that mobile node, along with the remaining lifetime of that association.

Correspondent Node
A peer node with which a mobile node is communicating. The correspondent node may be either mobile or stationary.

Home page link
Any page link other than the mobile nodes home link.

Foreign address
An IP address assigned to a mobile node within its home Link.

Home Agent
A router on a mobile nodes home page link with which the mobile node has registered its current [5] care-of-address. While the mobile node is away ,from the home the home agent intercepts packets on the home page link destined to the mobile nodes home address, encapsulates them, and tunnels them to the mobile nodes registered care of address.


OVERVIEW OF MOBILE IPv6
Mobile IPv6 messages
Mobile ipv6 requires the exchange of additional information. All new messages used in mobile ipv6 are defined as IPv6 Destination options. [4] These options are used in IPv6 to carry additional information that needs to be examined only by a packets destination node.
The following four new destination options are defined in mobile IPv6.

• Binding update
The binding update option is used by a mobile node to inform its home agent or any other correspondent node about its current care-of-address.