<s>
Mapping	B-Protocol
of	I-Protocol
Address	I-Protocol
and	I-Protocol
Port	I-Protocol
(	O
MAP	O
)	O
is	O
a	O
proposal	O
that	O
combines	O
A+P	B-Protocol
port	O
address	O
translation	O
with	O
the	O
tunneling	O
of	O
legacy	O
IPv4	O
protocol	O
packets	O
over	O
an	O
ISP	O
's	O
internal	O
IPv6	O
network	O
.	O
</s>
<s>
MAP	O
uses	O
the	O
extra	O
bits	O
available	O
in	O
the	O
IPv6	O
address	O
to	O
contain	O
the	O
extra	O
port	O
range	O
identifier	O
bits	O
of	O
the	O
A+P	B-Protocol
addressing	O
pair	O
that	O
cannot	O
be	O
encoded	O
directly	O
into	O
the	O
IPv4	O
address	O
,	O
thus	O
eliminating	O
the	O
need	O
for	O
"	O
port	O
routing	O
"	O
within	O
the	O
carrier	O
network	O
by	O
leveraging	O
the	O
provider	O
's	O
own	O
IPv6	O
rollout	O
.	O
</s>
<s>
In	O
effect	O
,	O
MAP	O
is	O
an	O
(	O
almost	O
)	O
stateless	O
alternative	O
to	O
Carrier-grade	B-Protocol
NAT	I-Protocol
and	O
DS-Lite	O
that	O
pushes	O
the	O
IPv4	O
IP	O
address/port	O
translation	O
function	O
(	O
and	O
therefore	O
the	O
maintenance	O
of	O
NAT	O
state	O
)	O
entirely	O
into	O
the	O
existing	O
customer	O
premises	O
equipment	O
IPv4	O
NAT	O
implementation	O
,	O
thus	O
avoiding	O
the	O
NAT444	B-Protocol
and	O
statefulness	O
problems	O
of	O
carrier-grade	B-Protocol
NAT	I-Protocol
.	O
</s>
