<s>
Connection-oriented	B-Protocol
Ethernet	I-Protocol
refers	O
to	O
the	O
transformation	O
of	O
Ethernet	O
,	O
a	O
connectionless	B-Protocol
communication	I-Protocol
system	O
by	O
design	O
,	O
into	O
a	O
connection-oriented	B-Protocol
system	O
.	O
</s>
<s>
The	O
aim	O
of	O
connection-oriented	B-Protocol
Ethernet	I-Protocol
is	O
to	O
create	O
a	O
networking	O
technology	O
that	O
combines	O
the	O
flexibility	O
and	O
cost-efficiency	O
of	O
Ethernet	O
with	O
the	O
reliability	O
of	O
connection-oriented	B-Protocol
protocols	I-Protocol
.	O
</s>
<s>
Connection-oriented	B-Protocol
Ethernet	I-Protocol
is	O
used	O
in	O
commercial	O
carrier	O
grade	O
networks	O
.	O
</s>
<s>
Packet-switched	B-Protocol
networks	I-Protocol
are	O
different	O
,	O
as	O
they	O
offer	O
services	O
based	O
on	O
statistical	B-Algorithm
multiplexing	I-Algorithm
.	O
</s>
<s>
The	O
IP-MPLS	O
approach	O
aims	O
at	O
providing	O
guaranteed	O
services	O
over	O
the	O
Internet	O
Protocol	O
using	O
a	O
multitude	O
of	O
networking	O
protocols	O
to	O
create	O
,	O
maintain	O
and	O
handle	O
packet	O
data	O
streams	O
.	O
</s>
<s>
This	O
has	O
resulted	O
in	O
the	O
emergence	O
of	O
connection-oriented	B-Protocol
Ethernet	I-Protocol
which	O
includes	O
a	O
variety	O
of	O
methodologies	O
to	O
utilize	O
Ethernet	O
for	O
the	O
same	O
functionalities	O
otherwise	O
based	O
on	O
extensive	O
IP	O
protocols	O
.	O
</s>
<s>
The	O
challenge	O
of	O
carrier	B-Protocol
Ethernet	I-Protocol
is	O
to	O
add	O
carrier-grade	O
functionality	O
to	O
Ethernet	O
equipment	O
without	O
losing	O
the	O
cost-effectiveness	O
and	O
simplicity	O
that	O
makes	O
it	O
attractive	O
in	O
the	O
first	O
place	O
.	O
</s>
<s>
To	O
meet	O
this	O
challenge	O
,	O
common	O
connection-oriented	B-Protocol
Ethernet	I-Protocol
solutions	O
have	O
chosen	O
to	O
rid	O
themselves	O
of	O
the	O
complex	O
parts	O
of	O
packet	O
transport	O
to	O
achieve	O
stability	O
and	O
control	O
.	O
</s>
<s>
Key	O
connection-oriented	B-Protocol
Ethernet	I-Protocol
technologies	O
used	O
to	O
achieve	O
this	O
include	O
mainly	O
IEEE	O
802.1ah	O
,	O
Provider	B-Protocol
Backbone	I-Protocol
Transport	I-Protocol
and	O
MPLS-TP	B-Protocol
,	O
and	O
formerly	O
T-MPLS	B-Protocol
.	O
</s>
<s>
Provider	B-Protocol
Backbone	I-Protocol
Transport	I-Protocol
(	O
PBT	O
)	O
is	O
connection-oriented	B-Protocol
switch	O
operation	O
scheme	O
and	O
network	O
management	O
architecture	O
.	O
</s>
<s>
It	O
defines	O
methods	O
to	O
emulate	O
connection-oriented	B-Protocol
networks	I-Protocol
by	O
providing	O
"	O
nailed-up	O
"	O
trunks	O
through	O
a	O
packet-switched	B-Protocol
network	I-Protocol
.	O
</s>
<s>
Configuration	O
is	O
performed	O
by	O
a	O
centralized	O
management	O
server	O
like	O
in	O
SDH	B-Protocol
networks	O
,	O
though	O
in	O
the	O
future	O
a	O
control	O
plane	O
may	O
be	O
added	O
.	O
</s>
<s>
PBT	O
has	O
been	O
presented	O
to	O
IEEE802	O
and	O
a	O
new	O
project	O
has	O
been	O
approved	O
to	O
standardize	O
it	O
under	O
the	O
name	O
of	O
Provider	B-Protocol
Backbone	I-Protocol
Bridge	I-Protocol
Traffic	I-Protocol
Engineering	I-Protocol
(	O
PBB-TE	B-Protocol
)	O
(	O
IEEE	B-Protocol
802.1Qay	I-Protocol
)	O
,	O
a	O
modification	O
to	O
PBB	O
.	O
</s>
<s>
Additionally	O
Ethernet	O
is	O
being	O
reinforced	O
with	O
operations	B-Architecture
,	I-Architecture
administration	I-Architecture
,	I-Architecture
and	I-Architecture
maintenance	I-Architecture
(	O
OAM	O
)	O
capabilities	O
through	O
the	O
work	O
of	O
various	O
standard	O
bodies	O
(	O
IEEE	O
802.1ag	O
,	O
ITU-T	O
Y.1731	O
and	O
G.8021	O
,	O
IEEE	B-Protocol
802.3ah	I-Protocol
)	O
.	O
</s>
<s>
PBT/PBB	O
equipment	O
leverages	O
economies	O
of	O
scale	O
inherent	O
in	O
Ethernet	O
,	O
promising	O
about	O
30%40%	O
cheaper	O
solutions	O
compared	O
to	O
T-MPLS	B-Protocol
equipment	O
with	O
identical	O
features	O
and	O
capabilities	O
,	O
making	O
PBT	O
a	O
better	O
overall	O
return	O
on	O
investment	O
.	O
</s>
<s>
T-MPLS	B-Protocol
,	O
as	O
its	O
name	O
implies	O
,	O
is	O
a	O
derivative	O
of	O
MPLS	B-Protocol
that	O
renounces	O
all	O
MPLS	B-Protocol
signaling	O
features	O
and	O
,	O
like	O
PBT	O
,	O
uses	O
a	O
centralized	O
control-plane	O
to	O
perform	O
routing	O
and	O
traffic	O
engineering	O
.	O
</s>
<s>
T-MPLS	B-Protocol
is	O
currently	O
being	O
standardized	O
only	O
at	O
ITU-T	O
and	O
enjoys	O
strong	O
vendor	O
support	O
but	O
little	O
carrier	O
support	O
.	O
</s>
<s>
As	O
a	O
native	O
MPLS	B-Protocol
derivative	O
,	O
T-MPLS	B-Protocol
can	O
be	O
easily	O
implemented	O
over	O
existing	O
MPLS	B-Protocol
routers	O
.	O
</s>
<s>
However	O
,	O
T-MPLS	B-Protocol
has	O
been	O
stripped	O
of	O
the	O
characteristics	O
which	O
originally	O
made	O
it	O
attractive	O
to	O
carriers	O
—	O
control-plane	O
automation	O
,	O
signaling	O
,	O
and	O
QoS	O
—	O
and	O
therefore	O
has	O
yet	O
to	O
prove	O
its	O
benefits	O
for	O
the	O
transport	O
network	O
.	O
</s>
<s>
T-MPLS	B-Protocol
OAM	O
,	O
defined	O
in	O
ITU	O
Y.1711	O
,	O
is	O
different	O
from	O
MPLS	B-Protocol
OAM	O
and	O
lacks	O
powerful	O
management	O
tools	O
that	O
carriers	O
typically	O
expect	O
.	O
</s>
<s>
T	O
MPLS	B-Protocol
was	O
abandoned	O
by	O
the	O
ITU-T	O
in	O
favor	O
of	O
MPLS-TP	B-Protocol
in	O
December	O
2008	O
.	O
</s>
<s>
MPLS-TP	B-Protocol
or	O
MPLS	B-Protocol
Transport	O
Profile	O
is	O
a	O
profile	O
of	O
MPLS	B-Protocol
developed	O
in	O
cooperation	O
between	O
ITU-T	O
and	O
IETF	O
since	O
2008	O
as	O
a	O
connection-oriented	B-Protocol
packet-switched	B-Protocol
(	O
CO-PS	O
)	O
extension	O
.	O
</s>
<s>
Based	O
on	O
the	O
same	O
architectural	O
principles	O
of	O
layered	O
networking	O
that	O
are	O
used	O
in	O
longstanding	O
transport	O
network	O
technologies	O
like	O
SDH	B-Protocol
,	O
SONET	B-Protocol
,	O
and	O
OTN	B-Protocol
,	O
MPLS-TP	B-Protocol
provides	O
a	O
reliable	O
packet-based	O
L2	O
technology	O
that	O
is	O
comparable	O
to	O
circuit-based	O
transport	O
networking	O
,	O
and	O
thus	O
aligned	O
with	O
current	O
organizational	O
processes	O
and	O
large-scale	O
work	O
procedures	O
similar	O
to	O
other	O
packet	O
transport	O
technologies	O
.	O
</s>
<s>
Services	O
in	O
the	O
data	O
network	O
are	O
typically	O
classified	O
into	O
2	O
major	O
categories	O
:	O
Committed	B-Protocol
Information	I-Protocol
Rate	I-Protocol
(	O
CIR	O
)	O
and	O
Excess	O
Information	O
Rate	O
(	O
EIR	O
)	O
.	O
</s>
<s>
To	O
achieve	O
this	O
PBB/PBT	O
and	O
T-MPLS	B-Protocol
approaches	O
largely	O
under-provision	O
network	O
resources	O
,	O
in	O
order	O
to	O
avoid	O
a	O
situation	O
where	O
a	O
burst	O
in	O
best-effort	O
traffic	O
would	O
jeopardize	O
the	O
ability	O
to	O
serve	O
committed	O
traffic	O
,	O
leading	O
to	O
costly	O
penalties	O
.	O
</s>
<s>
With	O
PBB/PBT	O
and	O
T-MPLS	B-Protocol
,	O
the	O
amount	O
of	O
bandwidth	O
available	O
to	O
a	O
particular	O
client	O
greatly	O
depends	O
on	O
the	O
client	O
's	O
location	O
and	O
the	O
prevailing	O
traffic	O
conditions	O
.	O
</s>
