<s>
The	O
STM-1	B-Protocol
(	O
Synchronous	O
Transport	O
Module	O
level-1	O
)	O
is	O
the	O
SDH	B-Protocol
ITU-T	O
fiber	B-Architecture
optic	I-Architecture
network	O
transmission	O
standard	O
.	O
</s>
<s>
Higher	O
levels	O
go	O
up	O
by	O
a	O
factor	O
of	O
4	O
at	O
a	O
time	O
:	O
the	O
other	O
currently	O
supported	O
levels	O
are	O
STM-4	B-Protocol
,	O
STM-16	B-Protocol
,	O
STM-64	B-Protocol
and	O
STM-256	B-Protocol
.	O
</s>
<s>
Above	O
STM-256	B-Protocol
wavelength-division	B-Architecture
multiplexing	I-Architecture
(	O
WDM	O
)	O
is	O
commonly	O
used	O
in	O
submarine	O
cabling	O
.	O
</s>
<s>
The	O
STM-1	B-Protocol
frame	O
is	O
on	O
the	O
basic	O
transmission	O
format	O
for	O
SDH	B-Protocol
(	O
Synchronous	B-Protocol
Digital	I-Protocol
Hierarchy	I-Protocol
)	O
.	O
</s>
<s>
An	O
STM-1	B-Protocol
frame	O
has	O
a	O
byte-oriented	O
structure	O
with	O
9	O
rows	O
and	O
270	O
columns	O
of	O
bytes	O
,	O
for	O
a	O
total	O
of	O
2,430	O
bytes	O
(	O
9	O
rows	O
*	O
270	O
columns	O
=	O
2430	O
bytes	O
)	O
.	O
</s>
<s>
The	O
STM-1	B-Protocol
base	O
frame	O
is	O
structured	O
with	O
the	O
following	O
characteristics	O
:	O
</s>
<s>
It	O
is	O
used	O
to	O
give	O
a	O
path	O
through	O
an	O
SDH	B-Protocol
Network	O
a	O
"	O
Name	O
"	O
.	O
</s>
<s>
This	O
check	O
is	O
carried	O
out	O
with	O
a	O
Bit	O
Interleaved	O
Parity	O
check	O
(	O
BIP-8	B-Protocol
)	O
.	O
</s>
<s>
The	O
Multiplex	O
Section	B-Protocol
OverHead	I-Protocol
uses	O
the	O
5th	O
through	O
9th	O
rows	O
,	O
and	O
first	O
9	O
columns	O
in	O
the	O
STM-1	B-Protocol
frame	O
.	O
</s>
<s>
In	O
case	O
of	O
a	O
failure	O
,	O
the	O
STM	O
frames	O
can	O
be	O
routed	O
new	O
with	O
the	O
help	O
of	O
the	O
K1	O
,	O
K2	O
Bytes	O
through	O
the	O
SDH	B-Protocol
Network	O
.	O
</s>
