<s>
Anything	B-Protocol
In	I-Protocol
Anything	I-Protocol
(	O
AYIYA	B-Protocol
)	O
is	O
a	O
computer	O
networking	O
protocol	O
for	O
managing	O
IP	O
tunneling	B-Protocol
protocols	I-Protocol
in	O
use	O
between	O
separated	O
Internet	B-Protocol
Protocol	I-Protocol
networks	O
.	O
</s>
<s>
It	O
is	O
most	O
often	O
used	O
to	O
provide	O
IPv6	B-Protocol
transit	O
over	O
an	O
IPv4	B-Protocol
network	I-Protocol
link	O
when	O
network	B-Protocol
address	I-Protocol
translation	I-Protocol
masquerades	O
a	O
private	O
network	O
with	O
a	O
single	O
IP	B-Protocol
address	I-Protocol
that	O
may	O
change	O
frequently	O
because	O
of	O
DHCP	B-Protocol
provisioning	O
by	O
Internet	O
service	O
providers	O
.	O
</s>
<s>
Many	O
consumer	O
networks	O
are	O
provisioned	O
by	O
Internet	O
service	O
providers	O
using	O
network	B-Protocol
address	I-Protocol
translation	I-Protocol
(	O
NAT	O
)	O
which	O
precludes	O
the	O
usage	O
of	O
IP	B-Protocol
protocol	I-Protocol
41	O
tunnels	O
(	O
IPv6	B-Protocol
tunnelled	O
in	O
IPv4	B-Protocol
,	O
either	O
RFC	O
4213	O
or	O
RFC	O
3056	O
)	O
unless	O
they	O
manually	O
reconfigure	O
their	O
NAT	O
setup	O
.	O
</s>
<s>
This	O
is	O
an	O
undesired	O
situation	O
as	O
it	O
limits	O
the	O
deployment	O
of	O
IPv6	B-Protocol
,	O
which	O
was	O
meant	O
to	O
solve	O
the	O
problem	O
of	O
the	O
disturbance	O
in	O
end	O
to	O
end	O
communications	O
caused	O
by	O
NATs	O
,	O
which	O
were	O
created	O
because	O
of	O
limited	O
address	O
space	O
in	O
the	O
first	O
place	O
.	O
</s>
<s>
This	O
problem	O
can	O
be	O
solved	O
by	O
tunneling	O
the	O
IPv6	B-Protocol
packets	O
over	O
either	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	O
)	O
,	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	O
)	O
or	O
the	O
Stream	B-Protocol
Control	I-Protocol
Transmission	I-Protocol
Protocol	I-Protocol
(	O
SCTP	B-Protocol
)	O
.	O
</s>
<s>
Taking	O
into	O
consideration	O
that	O
multiple	O
separate	O
endpoints	O
could	O
be	O
behind	O
the	O
same	O
NAT	O
or	O
that	O
the	O
public	O
endpoint	O
receives	O
a	O
new	O
IP	B-Protocol
address	I-Protocol
,	O
there	O
is	O
a	O
need	O
to	O
identify	O
the	O
endpoint	O
that	O
certain	O
packets	O
are	O
coming	O
from	O
and	O
endpoints	O
need	O
to	O
be	O
able	O
to	O
change	O
e.g.	O
</s>
<s>
An	O
example	O
is	O
IPv6-in-UDP-in-IPv4	O
,	O
which	O
is	O
a	O
typical	O
setup	O
that	O
can	O
be	O
used	O
by	O
IPv6	B-Protocol
tunnel	I-Protocol
brokers	I-Protocol
.	O
</s>
<s>
AYIYA	B-Protocol
may	O
be	O
used	O
to	O
provision	O
mobile	O
hosts	O
by	O
tunneling	O
traffic	O
from	O
the	O
Home	O
Address	O
to	O
the	O
Home	O
Agent	O
over	O
an	O
underlying	O
network	O
.	O
</s>
<s>
Any	O
remote	O
host	O
that	O
the	O
mobile	O
host	O
communicates	O
with	O
does	O
not	O
need	O
AYIYA	B-Protocol
support	O
.	O
</s>
<s>
When	O
the	O
remote	O
host	O
does	O
support	O
AYIYA	B-Protocol
,	O
it	O
could	O
also	O
directly	O
set	O
up	O
a	O
tunnel	O
with	O
the	O
mobile	O
host	O
establishing	O
a	O
direct	O
tunnel	O
.	O
</s>
<s>
The	O
remote	O
host	O
can	O
determine	O
whether	O
a	O
host	O
supports	O
AYIYA	B-Protocol
by	O
querying	O
for	O
Domain	O
Name	O
System	O
records	O
and	O
use	O
a	O
public/private	O
key	O
algorithm	O
to	O
authenticate	O
the	O
packets	O
.	O
</s>
<s>
Using	O
AYIYA	B-Protocol
to	O
provide	O
IPv6	B-Protocol
for	O
a	O
host	O
is	O
in	O
effect	O
already	O
providing	O
mobility	O
for	O
that	O
end	O
point	O
as	O
it	O
can	O
use	O
its	O
IPv6	B-Protocol
address	O
regardless	O
of	O
geographic	O
location	O
.	O
</s>
<s>
For	O
IPv6	B-Protocol
over	O
IPv4-UDP	O
operation	O
,	O
as	O
in	O
the	O
most	O
common	O
use	O
scenario	O
,	O
the	O
identity	O
is	O
the	O
IPv6	B-Protocol
Address	O
of	O
the	O
endpoint	O
(	O
16	O
bytes	O
)	O
and	O
the	O
signature	O
is	O
an	O
SHA1	O
hash	O
(	O
20	O
bytes	O
)	O
.	O
</s>
<s>
Encapsulated	O
in	O
UDP	O
and	O
IPv4	B-Protocol
the	O
tunnel	O
overhead	O
is	O
44	O
+	O
8	O
+	O
20	O
=	O
72	O
bytes	O
.	O
</s>
<s>
The	O
AYIYA	B-Protocol
protocol	O
has	O
been	O
implemented	O
in	O
AICCU	B-Language
.	O
</s>
