<s>
The	O
p-Cycle	B-Protocol
protection	I-Protocol
scheme	O
is	O
a	O
technique	O
to	O
protect	O
a	O
mesh	B-Architecture
network	I-Architecture
from	O
a	O
failure	O
of	O
a	O
link	O
,	O
with	O
the	O
benefits	O
of	O
ring	O
like	O
recovery	O
speed	O
and	O
mesh-like	O
capacity	O
efficiency	O
,	O
similar	O
to	O
that	O
of	O
a	O
shared	O
backup	O
path	O
protection	O
(	O
SBPP	O
)	O
.	O
</s>
<s>
p-Cycle	B-Protocol
protection	I-Protocol
was	O
invented	O
in	O
late	O
1990s	O
,	O
with	O
research	O
and	O
development	O
done	O
mostly	O
by	O
Wayne	O
D	O
.	O
Grover	O
,	O
and	O
D	O
.	O
Stamatelakis	O
.	O
</s>
<s>
In	O
1998	O
the	O
p-Cycle	O
became	O
a	O
promising	O
technique	O
for	O
recovery	O
in	O
mesh	B-Architecture
networks	I-Architecture
because	O
of	O
the	O
combined	O
benefits	O
of	O
ring	O
network	O
recovery	O
speed	O
and	O
mesh	O
like	O
capacity	O
efficiency	O
.	O
</s>
<s>
In	O
a	O
mesh	B-Architecture
network	I-Architecture
,	O
the	O
spare	O
capacity	O
is	O
used	O
to	O
create	O
the	O
ring	O
like	O
structures	O
as	O
shown	O
in	O
Figure	O
1	O
.	O
</s>
<s>
Flow	O
p-cycle	O
-	O
a	O
p-cycle	O
that	O
offers	O
protection	O
for	O
links	O
that	O
are	O
on	O
the	O
p-cycle	O
,	O
the	O
opposite	O
of	O
the	O
Span	O
p-cycle	B-Protocol
protection	I-Protocol
scheme	O
.	O
</s>
<s>
After	O
the	O
p-cycles	O
are	O
found	O
,	O
the	O
working	O
demand	O
is	O
routed	O
on	O
the	O
network	O
within	O
the	O
p-cycle	B-Protocol
protection	I-Protocol
domain	O
.	O
</s>
<s>
The	O
Heuristic	B-Algorithm
method	O
presented	O
called	O
the	O
ER-based	O
unity-p-cycle	O
,	O
shows	O
an	O
attractive	O
solution	O
to	O
solve	O
the	O
problem	O
with	O
creating	O
p-cycles	O
without	O
the	O
use	O
of	O
ILP	O
.	O
</s>
<s>
All	O
of	O
the	O
nodes	O
adopt	O
this	O
behavior	O
and	O
this	O
is	O
accomplished	O
in	O
a	O
round-robin	B-Algorithm
scheme	O
.	O
</s>
<s>
A	O
study	O
performed	O
last	O
years	O
showed	O
that	O
an	O
efficient	O
way	O
to	O
create	O
p-cycles	O
can	O
be	O
achieved	O
in	O
mesh	B-Architecture
networks	I-Architecture
that	O
are	O
flat	O
.	O
</s>
<s>
As	O
an	O
alternative	O
a	O
concept	O
of	O
semi-homogeneous	O
mesh	B-Architecture
networks	I-Architecture
was	O
developed	O
.	O
</s>
<s>
The	O
idea	O
behind	O
p-cycles	O
protection	O
was	O
an	O
ability	O
to	O
offer	O
protection	O
in	O
mesh	O
optical	O
networks	O
by	O
combining	O
the	O
benefits	O
of	O
ring	O
like	O
recovery	O
speed	O
and	O
the	O
efficiency	O
of	O
a	O
mesh	B-Architecture
network	I-Architecture
,	O
however	O
the	O
concept	O
is	O
not	O
only	O
limited	O
to	O
transport	O
optical	O
networks	O
and	O
can	O
be	O
extended	O
to	O
higher	O
levels	O
and	O
other	O
network	O
types	O
:	O
</s>
