<s>
In	O
the	O
modern	O
era	O
,	O
it	O
is	O
important	O
to	O
protect	O
multicast	O
connections	O
in	O
an	O
optical	B-Protocol
mesh	I-Protocol
network	I-Protocol
.	O
</s>
<s>
Multicast	O
applications	O
include	O
multimedia	O
,	O
medical	B-Application
imaging	I-Application
,	O
digital	O
audio	O
,	O
HDTV	B-Device
,	O
video	B-Application
conferencing	I-Application
,	O
interactive	O
distance	O
learning	O
,	O
and	O
distributed	O
games	O
.	O
</s>
<s>
In	O
order	O
to	O
support	O
multi-casting	O
,	O
the	O
WDM	B-Architecture
network	O
requires	O
multicast-capable	O
wavelength-routing	O
switches	O
at	O
the	O
network	O
node	O
.	O
</s>
<s>
The	O
other	O
is	O
transparent	O
switch	O
architecture	O
which	O
utilizes	O
all	O
optical	B-Protocol
cross-connects	I-Protocol
(	O
OXCs	B-Protocol
)	O
.	O
</s>
<s>
Multicast	B-Protocol
lightpaths	I-Protocol
protection	O
refers	O
to	O
an	O
immediate	O
response	O
of	O
the	O
network	O
after	O
a	O
failure	O
to	O
switch	O
the	O
traffic	O
on	O
another	O
path	O
.	O
</s>
<s>
Path	O
protection	O
technique	O
for	O
multicast	O
connections	O
(	O
multiple	O
unicast	B-Protocol
connections	O
)	O
:	O
</s>
