<s>
Mobile	B-Protocol
IP	I-Protocol
(	O
or	O
MIP	O
)	O
is	O
an	O
Internet	O
Engineering	O
Task	O
Force	O
(	O
IETF	O
)	O
standard	O
communications	O
protocol	O
that	O
is	O
designed	O
to	O
allow	O
mobile	O
device	O
users	O
to	O
move	O
from	O
one	O
network	O
to	O
another	O
while	O
maintaining	O
a	O
permanent	O
IP	O
address	O
.	O
</s>
<s>
Mobile	B-Protocol
IP	I-Protocol
for	O
IPv4	B-Protocol
is	O
described	O
in	O
IETF	O
RFC	O
5944	O
,	O
and	O
extensions	O
are	O
defined	O
in	O
IETF	O
RFC	O
4721	O
.	O
</s>
<s>
Mobile	B-Protocol
IPv6	I-Protocol
,	O
the	O
IP	B-Protocol
mobility	I-Protocol
implementation	O
for	O
the	O
next	O
generation	O
of	O
the	O
Internet	B-Protocol
Protocol	I-Protocol
,	O
IPv6	B-Protocol
,	O
is	O
described	O
in	O
RFC	O
6275	O
.	O
</s>
<s>
The	O
Mobile	B-Protocol
IP	I-Protocol
allows	O
for	O
location-independent	O
routing	O
of	O
IP	O
datagrams	O
on	O
the	O
Internet	O
.	O
</s>
<s>
While	O
away	O
from	O
its	O
home	O
network	O
,	O
a	O
mobile	O
node	O
is	O
associated	O
with	O
a	O
care-of	B-Protocol
address	I-Protocol
which	O
identifies	O
its	O
current	O
location	O
and	O
its	O
home	O
address	O
is	O
associated	O
with	O
the	O
local	O
endpoint	O
of	O
a	O
tunnel	O
to	O
its	O
home	O
agent	O
.	O
</s>
<s>
Mobile	B-Protocol
IP	I-Protocol
specifies	O
how	O
a	O
mobile	O
node	O
registers	O
with	O
its	O
home	O
agent	O
and	O
how	O
the	O
home	O
agent	O
routes	O
datagrams	O
to	O
the	O
mobile	O
node	O
through	O
the	O
tunnel	O
.	O
</s>
<s>
In	O
many	O
applications	O
(	O
e.g.	O
,	O
VPN	B-Application
,	O
VoIP	B-Application
)	O
,	O
sudden	O
changes	O
in	O
network	O
connectivity	O
and	O
IP	O
address	O
can	O
cause	O
problems	O
.	O
</s>
<s>
Mobile	B-Protocol
IP	I-Protocol
was	O
designed	O
to	O
support	O
seamless	O
and	O
continuous	O
Internet	O
connectivity	O
.	O
</s>
<s>
Mobile	B-Protocol
IP	I-Protocol
is	O
most	O
often	O
found	O
in	O
wired	O
and	O
wireless	O
environments	O
where	O
users	O
need	O
to	O
carry	O
their	O
mobile	O
devices	O
across	O
multiple	O
LAN	O
subnets	O
.	O
</s>
<s>
Examples	O
of	O
use	O
are	O
in	O
roaming	O
between	O
overlapping	O
wireless	O
systems	O
,	O
e.g.	O
,	O
IP	O
over	O
DVB	B-Application
,	O
WLAN	B-Architecture
,	O
WiMAX	O
and	O
BWA	B-General_Concept
.	O
</s>
<s>
Mobile	B-Protocol
IP	I-Protocol
is	O
not	O
required	O
within	O
cellular	O
systems	O
such	O
as	O
3G	O
,	O
to	O
provide	O
transparency	O
when	O
Internet	O
users	O
migrate	O
between	O
cellular	O
towers	O
,	O
since	O
these	O
systems	O
provide	O
their	O
own	O
data	O
link	O
layer	O
handover	B-Protocol
and	O
roaming	O
mechanisms	O
.	O
</s>
<s>
However	O
,	O
it	O
is	O
often	O
used	O
in	O
3G	O
systems	O
to	O
allow	O
seamless	O
IP	B-Protocol
mobility	I-Protocol
between	O
different	O
packet	O
data	O
serving	O
node	O
(	O
PDSN	O
)	O
domains	O
.	O
</s>
<s>
The	O
goal	O
of	O
IP	B-Protocol
Mobility	I-Protocol
is	O
to	O
maintain	O
the	O
TCP	O
connection	O
between	O
a	O
mobile	O
host	O
and	O
a	O
static	O
host	O
while	O
reducing	O
the	O
effects	O
of	O
location	O
changes	O
while	O
the	O
mobile	O
host	O
is	O
moving	O
around	O
,	O
without	O
having	O
to	O
change	O
the	O
underlying	O
TCP/IP	O
.	O
</s>
<s>
A	O
mobile	O
node	O
has	O
two	O
addresses	O
–	O
a	O
permanent	O
home	O
address	O
and	O
a	O
care-of	B-Protocol
address	I-Protocol
(	O
CoA	O
)	O
,	O
which	O
is	O
associated	O
with	O
the	O
network	O
the	O
mobile	O
node	O
is	O
visiting	O
.	O
</s>
<s>
Two	O
kinds	O
of	O
entities	O
comprise	O
a	O
Mobile	B-Protocol
IP	I-Protocol
implementation	O
:	O
</s>
<s>
The	O
HA	O
acts	O
as	O
a	O
router	B-Protocol
on	O
a	O
mobile	O
host	O
's	O
(	O
MH	O
)	O
home	O
network	O
which	O
tunnels	O
datagrams	O
for	O
delivery	O
to	O
the	O
MH	O
when	O
it	O
is	O
away	O
from	O
home	O
,	O
maintains	O
a	O
location	O
directory	O
(	O
LD	O
)	O
for	O
the	O
MH	O
.	O
</s>
<s>
Foreign	O
agents	O
also	O
advertise	O
care-of	B-Protocol
addresses	I-Protocol
,	O
which	O
are	O
used	O
by	O
Mobile	B-Protocol
IP	I-Protocol
.	O
</s>
<s>
The	O
FA	O
acts	O
as	O
a	O
router	B-Protocol
on	O
a	O
MH	O
’s	O
visited	O
network	O
which	O
provides	O
routing	O
services	O
to	O
the	O
MH	O
while	O
registered	O
.	O
</s>
<s>
The	O
so-called	O
Care	B-Protocol
of	I-Protocol
Address	I-Protocol
is	O
a	O
termination	O
point	O
of	O
a	O
tunnel	O
toward	O
a	O
MH	O
,	O
for	O
datagrams	O
forwarded	O
to	O
the	O
MH	O
while	O
it	O
is	O
away	O
from	O
home	O
.	O
</s>
<s>
co-located	O
care-of	B-Protocol
address	I-Protocol
:	O
an	O
externally	O
obtained	O
local	O
address	O
that	O
a	O
MH	O
gets	O
.	O
</s>
<s>
Instead	O
of	O
forwarding	O
these	O
packets	O
to	O
a	O
destination	O
that	O
is	O
physically	O
in	O
the	O
same	O
network	O
as	O
the	O
home	O
agent	O
,	O
the	O
home	O
agent	O
redirects	O
these	O
packets	O
towards	O
the	O
remote	O
address	O
through	O
an	O
IP	B-Protocol
tunnel	I-Protocol
by	O
encapsulating	O
the	O
datagram	O
with	O
a	O
new	O
IP	O
header	O
using	O
the	O
care	B-Protocol
of	I-Protocol
address	I-Protocol
of	O
the	O
mobile	O
node	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
triangular	B-Protocol
routing	I-Protocol
or	O
"	O
route	O
optimization	O
"	O
(	O
RO	O
)	O
mode	O
.	O
</s>
<s>
This	O
is	O
needed	O
in	O
networks	O
whose	O
gateway	O
routers	B-Protocol
check	O
that	O
the	O
source	O
IP	O
address	O
of	O
the	O
mobile	O
host	O
belongs	O
to	O
their	O
subnet	O
or	O
discard	O
the	O
packet	O
otherwise	O
.	O
</s>
<s>
In	O
Mobile	B-Protocol
IPv6	I-Protocol
(	O
MIPv6	B-Protocol
)	O
,	O
"	O
reverse	O
tunneling	O
"	O
is	O
the	O
default	O
behaviour	O
,	O
with	O
RO	O
being	O
an	O
optional	O
behaviour	O
.	O
</s>
<s>
Enhancements	O
to	O
the	O
Mobile	B-Protocol
IP	I-Protocol
technique	O
,	O
such	O
as	O
Mobile	B-Protocol
IPv6	I-Protocol
and	O
Hierarchical	O
Mobile	B-Protocol
IPv6	I-Protocol
(	O
HMIPv6	O
)	O
defined	O
in	O
RFC	O
5380	O
,	O
are	O
being	O
developed	O
to	O
improve	O
mobile	O
communications	O
in	O
certain	O
circumstances	O
by	O
making	O
the	O
processes	O
more	O
secure	O
and	O
more	O
efficient	O
.	O
</s>
<s>
Fast	O
Handovers	B-Protocol
for	O
Mobile	B-Protocol
IPv6	I-Protocol
is	O
described	O
in	O
IETF	O
RFC	O
5568	O
.	O
</s>
<s>
Researchers	O
are	O
also	O
working	O
to	O
create	O
support	O
for	O
mobile	O
networking	O
between	O
entire	O
subnets	O
with	O
support	O
from	O
Mobile	B-Protocol
IPv6	I-Protocol
.	O
</s>
<s>
One	O
such	O
example	O
is	O
Network	B-Protocol
Mobility	I-Protocol
(	O
NEMO	O
)	O
Network	B-Protocol
Mobility	I-Protocol
Basic	O
Support	O
Protocol	O
by	O
the	O
IETF	O
Network	B-Protocol
Mobility	I-Protocol
Working	O
Group	O
which	O
supports	O
mobility	O
for	O
entire	O
Mobile	O
Networks	O
that	O
move	O
and	O
to	O
attach	O
to	O
different	O
points	O
in	O
the	O
Internet	O
.	O
</s>
<s>
The	O
protocol	O
is	O
an	O
extension	O
of	O
Mobile	B-Protocol
IPv6	I-Protocol
and	O
allows	O
session	O
continuity	O
for	O
every	O
node	O
in	O
the	O
Mobile	O
Network	O
as	O
the	O
network	O
moves	O
.	O
</s>
<s>
Care-of	B-Protocol
address	I-Protocol
The	O
care-of	B-Protocol
address	I-Protocol
of	O
a	O
mobile	O
device	O
is	O
the	O
network-native	O
IP	O
address	O
of	O
the	O
device	O
when	O
operating	O
in	O
a	O
foreign	O
network	O
.	O
</s>
<s>
A	O
home	O
agent	O
is	O
a	O
router	B-Protocol
on	O
a	O
mobile	O
node	O
’s	O
home	O
network	O
which	O
tunnels	O
datagrams	O
for	O
delivery	O
to	O
the	O
mobile	O
node	O
when	O
it	O
is	O
away	O
from	O
home	O
.	O
</s>
<s>
A	O
foreign	O
agent	O
is	O
a	O
router	B-Protocol
that	O
stores	O
information	O
about	O
mobile	O
nodes	O
visiting	O
its	O
network	O
.	O
</s>
<s>
Foreign	O
agents	O
also	O
advertise	O
care-of-addresses	O
which	O
are	O
used	O
by	O
Mobile	B-Protocol
IP	I-Protocol
.	O
</s>
<s>
Binding	O
A	O
binding	O
is	O
the	O
association	O
of	O
the	O
home	O
address	O
with	O
a	O
care-of	B-Protocol
address	I-Protocol
.	O
</s>
