<s>
Circuit	B-Architecture
emulation	I-Architecture
service	I-Architecture
(	O
CES	O
)	O
is	O
a	O
telecommunication	O
technology	O
used	O
to	O
send	O
information	O
over	O
asynchronous	O
data	O
networks	O
like	O
ATM	O
,	O
Ethernet	O
or	O
MPLS	B-Protocol
,	O
so	O
that	O
it	O
is	O
received	O
error-free	O
with	O
constant	O
delay	O
,	O
similar	O
to	O
a	O
leased	B-Architecture
line	I-Architecture
.	O
</s>
<s>
As	O
the	O
interest	O
for	O
ATM	O
is	O
declining	O
,	O
most	O
new	O
applications	O
work	O
over	O
packet-based	O
(	O
IP	B-Protocol
)	O
-networks	O
.	O
</s>
<s>
Examples	O
of	O
channels	O
needing	O
constant	O
delay	O
include	O
time-division	B-Protocol
multiplexed	I-Protocol
(	O
TDM	O
)	O
services	O
such	O
as	O
the	O
traditional	O
digital	B-Protocol
signal	I-Protocol
(	O
DS	O
)	O
and	O
the	O
E-carrier	O
circuits	O
.	O
</s>
<s>
The	O
core	O
networks	O
are	O
in	O
the	O
evolution	O
to	O
packet-switched	O
networks	O
such	O
as	O
Metro	B-Protocol
Ethernet	I-Protocol
,	O
IP/Ethernet	O
and	O
MPLS	B-Protocol
.	O
</s>
<s>
But	O
the	O
legacy	O
TDM	O
and	O
ATM	O
equipment	O
has	O
been	O
widely	O
deployed	O
in	O
traditional	O
telecommunication	O
networks	O
:	O
private	B-Device
branch	I-Device
exchanges	I-Device
(	O
PBX	O
)	O
in	O
enterprise	O
offices	O
,	O
PDH/SDH	O
equipment	O
in	O
carrier	O
offices	O
and	O
near	O
wireless	O
stations	O
.	O
</s>
<s>
Circuit	B-Architecture
emulation	I-Architecture
service	I-Architecture
technology	O
allows	O
companies	O
to	O
easily	O
migrate	O
to	O
packet-switched	O
networks	O
.	O
</s>
<s>
This	O
is	O
a	O
reverse	O
mapping	O
approach	O
with	O
regard	O
to	O
traditional	O
solutions	O
in	O
which	O
IP/ethernet	O
services	O
is	O
carried	O
in	O
ATM	O
or	O
PDH/SDH	O
protocols	O
.	O
</s>
<s>
CES	O
technology	O
makes	O
it	O
possible	O
to	O
leverage	O
the	O
modern	O
network	O
technologies	O
like	O
MPLS	B-Protocol
or	O
IP	B-Protocol
backbones	O
,	O
Metro	B-Protocol
Ethernet	I-Protocol
,	O
WiFi	O
,	O
IP-DSLAM	O
and	O
GPON/EPON	O
access	O
networks	O
.	O
</s>
