<s>
In	O
computer	B-Architecture
networks	I-Architecture
,	O
a	O
path	B-Protocol
computation	I-Protocol
element	I-Protocol
(	O
PCE	O
)	O
is	O
a	O
system	O
component	O
,	O
application	O
,	O
or	O
network	B-Protocol
node	I-Protocol
that	O
is	O
capable	O
of	O
determining	O
and	O
finding	O
a	O
suitable	O
route	O
for	O
conveying	O
data	O
between	O
a	O
source	O
and	O
a	O
destination	O
.	O
</s>
<s>
Constraint-based	O
path	O
computation	O
is	O
a	O
strategic	O
component	O
of	O
traffic	O
engineering	O
in	O
MPLS	B-Protocol
,	O
GMPLS	O
and	O
Segment	B-Protocol
Routing	I-Protocol
networks	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
determine	O
the	O
path	O
through	O
the	O
network	B-Architecture
that	O
traffic	O
should	O
follow	O
,	O
and	O
provides	O
the	O
route	O
for	O
each	O
Label	O
Switched	O
Path	O
(	O
LSP	O
)	O
that	O
is	O
set	O
up	O
.	O
</s>
<s>
But	O
path	O
computation	O
in	O
large	O
,	O
multi-domain	O
networks	O
may	O
be	O
very	O
complex	O
and	O
may	O
require	O
more	O
computational	O
power	O
and	O
network	B-Architecture
information	O
than	O
is	O
typically	O
available	O
at	O
a	O
network	B-Architecture
element	O
,	O
yet	O
may	O
still	O
need	O
to	O
be	O
more	O
dynamic	O
than	O
can	O
be	O
provided	O
by	O
a	O
management	O
system	O
.	O
</s>
<s>
A	O
PCE	O
might	O
be	O
a	O
network	B-Protocol
node	I-Protocol
,	O
network	B-Architecture
management	O
station	O
,	O
or	O
dedicated	O
computational	O
platform	O
that	O
is	O
resource-aware	O
and	O
has	O
the	O
ability	O
to	O
consider	O
multiple	O
constraints	O
for	O
sophisticated	O
path	O
computation	O
.	O
</s>
<s>
PCE	O
applications	O
compute	O
label	O
switched	O
paths	O
for	O
MPLS	B-Protocol
and	O
GMPLS	O
traffic	O
engineering	O
.	O
</s>
<s>
PCE	O
represents	O
a	O
vision	O
of	O
networks	O
that	O
separates	O
route	O
computations	O
from	O
the	O
signaling	O
of	O
end-to-end	O
connections	O
and	O
from	O
actual	O
packet	B-Protocol
forwarding	I-Protocol
.	O
</s>
<s>
There	O
is	O
a	O
basic	O
tutorial	O
on	O
PCE	O
as	O
presented	O
at	O
ISOCORE	O
's	O
MPLS2008	O
conference	O
and	O
a	O
tutorial	O
on	O
advanced	O
PCE	O
as	O
presented	O
at	O
ISOCORE	O
's	O
SDN/MPLS	O
2014	O
conference	O
.	O
</s>
<s>
Since	O
the	O
early	O
days	O
,	O
the	O
PCE	O
architecture	O
has	O
evolved	O
considerably	O
to	O
encompass	O
more	O
sophisticated	O
concepts	O
and	O
allow	O
application	O
to	O
more	O
complicated	O
network	B-Architecture
scenarios	O
.	O
</s>
<s>
Communications	O
between	O
the	O
PCE	O
and	O
PCC	O
are	O
achieved	O
using	O
the	O
Path	B-Protocol
Computation	I-Protocol
Element	I-Protocol
Communication	O
Protocol	O
(	O
PCEP	O
)	O
which	O
runs	O
over	O
the	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	O
)	O
.	O
</s>
