<s>
Optical	B-Protocol
performance	I-Protocol
monitoring	I-Protocol
(	O
OPM	O
)	O
is	O
used	O
for	O
managing	O
high	O
capacity	O
dense	B-Architecture
wavelength	I-Architecture
division	I-Architecture
multiplexing	I-Architecture
(	O
DWDM	O
)	O
optical	O
transmission	O
and	O
switching	O
systems	O
in	O
Next	B-Protocol
Generation	I-Protocol
Networks	I-Protocol
(	O
NGN	O
)	O
.	O
</s>
<s>
In	O
optical	O
communications	O
,	O
typical	O
roles	O
for	O
optical	B-Protocol
performance	I-Protocol
monitoring	I-Protocol
include	O
ensuring	O
correct	O
switching	O
in	O
reconfigurable	O
optical	O
add-drop	O
multiplexers	O
,	O
setting	O
levels	O
for	O
dynamic	O
equalization	O
of	O
the	O
gain	O
of	O
optical	O
amplifiers	O
,	O
and	O
providing	O
system	O
alarms	O
and	O
error	O
warning	O
for	O
lost	O
or	O
out	O
of	O
specification	O
optical	O
channels	O
.	O
</s>
<s>
The	O
optical	O
component	O
used	O
for	O
this	O
purpose	O
in	O
DWDM	O
networks	O
is	O
known	O
as	O
optical	B-Protocol
performance	I-Protocol
monitor	I-Protocol
(	O
OPM	O
)	O
or	O
optical	B-Protocol
channel	I-Protocol
monitor	I-Protocol
(	O
OCM	O
)	O
,	O
which	O
measures	O
channel	O
power	O
,	O
wavelength	O
,	O
and	O
optical	O
signal-to-noise	O
ratio	O
(	O
OSNR	O
)	O
for	O
each	O
channel	O
.	O
</s>
