<s>
ITU-T	O
Recommendation	O
G.709	O
Interfaces	O
for	O
the	O
Optical	B-Protocol
Transport	I-Protocol
Network	I-Protocol
(	O
OTN	B-Protocol
)	O
describes	O
a	O
means	O
of	O
communicating	O
data	O
over	O
an	O
optical	O
network	O
.	O
</s>
<s>
It	O
is	O
also	O
known	O
as	O
Optical	B-Protocol
Transport	I-Protocol
Hierarchy	I-Protocol
(	O
OTH	O
)	O
standard	O
.	O
</s>
<s>
The	O
G.709	O
OTUk	B-Protocol
signal	O
is	O
positioned	O
as	O
a	O
server	O
layer	O
signal	O
for	O
various	O
client	O
signals	O
,	O
e.g.	O
</s>
<s>
SDH/SONET	B-Protocol
,	O
ATM	O
,	O
IP	B-Protocol
,	O
Ethernet	O
,	O
Fibre	B-Architecture
Channel	I-Architecture
and	O
OTN	B-Protocol
ODUk	B-Protocol
(	O
where	O
k	O
=	O
0	O
,	O
1	O
,	O
2	O
,	O
2e	O
,	O
3	O
,	O
3e2	O
,	O
4	O
or	O
flex	O
)	O
.	O
</s>
<s>
Work	O
on	O
support	O
for	O
InfiniBand	B-Architecture
and	O
Common	O
Public	O
Radio	O
Interface	O
client	O
signals	O
is	O
currently	O
in	O
progress	O
.	O
</s>
<s>
ODUk	B-Protocol
contains	O
the	O
OPUk	O
with	O
additional	O
overhead	O
bytes	O
(	O
e.g.	O
</s>
<s>
TTI	O
,	O
BIP8	B-Protocol
,	O
GCC1/2	B-Protocol
,	O
TCM	O
etc	O
.	O
</s>
<s>
OTUk	B-Protocol
is	O
the	O
section	O
and	O
includes	O
framing	O
,	O
TTI	O
,	O
BIP8	B-Protocol
and	O
GCC0	B-Protocol
bytes	O
.	O
</s>
<s>
FEC	B-Error_Name
–	O
The	O
standard	O
FEC	B-Error_Name
code	O
(	O
described	O
in	O
G.975	O
)	O
is	O
a	O
Reed	B-Error_Name
–	I-Error_Name
Solomon	I-Error_Name
coding	O
calculated	O
across	O
the	O
payload	O
(	O
OPU	O
)	O
columns	O
.	O
</s>
<s>
The	O
FEC	B-Error_Name
code	O
also	O
extends	O
the	O
distance	O
the	O
optical	O
signal	O
can	O
travel	O
before	O
requiring	O
regeneration	O
.	O
</s>
<s>
G.709	O
offers	O
advanced	O
OAM&P	B-Architecture
capabilities	O
such	O
as	O
Tandem	O
Connection	O
Monitoring	O
(	O
TCM	O
)	O
,	O
End	O
to	O
End	O
performance	O
monitoring	O
,	O
connectivity	O
monitoring	O
,	O
signal	O
quality	O
supervision	O
and	O
General	B-Protocol
Communication	I-Protocol
Channel	I-Protocol
(	O
GCC	O
)	O
.	O
</s>
<s>
Unlike	O
SDH/SONET	B-Protocol
,	O
the	O
line	O
rate	O
is	O
increased	O
by	O
maintaining	O
the	O
G.709	O
frame	O
structure	O
(	O
4	O
rows	O
x	O
4080	O
columns	O
)	O
and	O
decreasing	O
the	O
frame	O
period	O
(	O
in	O
SDH/SONET	B-Protocol
the	O
frame	O
structure	O
is	O
increased	O
and	O
the	O
frame	O
period	O
of	O
125	O
µs	O
is	O
maintained	O
)	O
.	O
</s>
