<s>
4over6	B-Protocol
is	O
an	O
IPv6	B-Protocol
transition	I-Protocol
technology	I-Protocol
.	O
</s>
<s>
It	O
is	O
intended	O
as	O
a	O
mechanism	O
for	O
Internet	O
service	O
providers	O
to	O
provide	O
continued	O
access	O
to	O
the	O
IPv4	B-Protocol
Internet	I-Protocol
over	O
an	O
IPv6-only	O
service	O
provider	O
infrastructure	O
.	O
</s>
<s>
There	O
are	O
currently	O
two	O
versions	O
of	O
the	O
protocol	O
:	O
Public	B-Protocol
4over6	I-Protocol
which	O
is	O
deployed	O
but	O
not	O
recommended	O
for	O
new	O
implementations	O
,	O
and	O
Lightweight	B-Protocol
4over6	I-Protocol
which	O
is	O
an	O
extension	O
to	O
the	O
Dual-Stack	O
Lite	O
architecture	O
.	O
</s>
