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><H1
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><A
NAME="intro"
></A
>1. Introduction</H1
><P
> This document describes the software and procedures to set up and
use mobile IPv6 for Linux. The <A
HREF="http://www.ietf.org/internet-drafts/draft-ietf-mobileip-ipv6-24.txt"
TARGET="_top"
> "Mobility Support in IPv6" draft </A
> answers the
<EM
>what</EM
> and <EM
>why</EM
> of mobile IP:
</P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="WhatisMIPv6"
></A
>1.1. What is Mobile IP?</H2
><P
> <SPAN
CLASS="QUOTE"
>"Each mobile node is always identified by its home
address, regardless of its current point of attachment to the
Internet. While situated away from its home, a mobile node is also
associated with a care-of address, which provides information
about the mobile node's current location. IPv6 packets addressed
to a mobile node's home address are transparently routed to its
care-of address via the mobile nodes Home Agent (HA). The
protocol enables IPv6 nodes to cache the binding of a mobile
node's home address with its care-of address, and then to send any
packets destined for the mobile node directly to it at this
care-of address."</SPAN
> --- draft-ietf-mipv6-24, page 1-2.
</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="WhyMIPv6"
></A
>1.2. Why Mobile IP?</H2
><P
> <SPAN
CLASS="QUOTE"
>"Without specific support for mobility in IPv6, packets destined to a
mobile node (host or router) would not be able to reach it while the
mobile node is away from its home link (the link on which its home
IPv6 subnet prefix is in use), since routing is based on the subnet
prefix in a packet's destination IP address. In order to continue
communication in spite of its movement, a mobile node could change its
IP address each time it moves to a new link, but the mobile node would
then not be able to maintain transport and higher-layer connections
when it changes location. Mobility support in IPv6 is particularly
important, as mobile computers are likely to account for a majority or
at least a substantial fraction of the population of the Internet
during the lifetime of IPv6."</SPAN
> --- draft-ietf-mipv6-24, page 6.
</P
><P
> For all the details, read the <A
HREF="http://www.ietf.org/internet-drafts/draft-ietf-mobileip-ipv6-24.txt"
TARGET="_top"
> "Mobility Support in IPv6" draft</A
>
</P
></DIV
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><H2
CLASS="sect2"
><A
NAME="HowWork"
></A
>1.3. How does it work?</H2
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="images/Mobile-IP.png"
ALIGN="center"
WIDTH="520"><DIV
CLASS="caption"
><P
>Mobile IP</P
></DIV
></P
></DIV
><P
> <P
></P
><OL
TYPE="1"
><LI
><P
> The Mobile Node (MN) travels to a foreign network and gets a
new care-of-address.</P
></LI
><LI
><P
> The MN performs a binding update to its Home Agent (HA) (the
new care-of-address gets registered at HA). HA sends a binding
acknowledgement to MN.</P
></LI
><LI
><P
>A Correspondent Node (CN) wants to contact the MN. The HA
intercepts packets destined to the MN.</P
></LI
><LI
><P
>The HA then tunnels all packets to the MN from the CN using
MN's care-of-address.</P
></LI
><LI
><P
>When the MN answers the CN, it may use its current
care-of-address (and perform a binding to the CN) and communicate
with the CN directly (optimized routing) or it can tunnel all its
packets through the HA.</P
></LI
></OL
>
</P
><P
>See figure <A
HREF="intro.html#mobileIP"
>"Mobile IP"</A
> for
an explanation.
</P
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