<s>
Data	B-Protocol
center	I-Protocol
bridging	I-Protocol
(	O
DCB	O
)	O
is	O
a	O
set	O
of	O
enhancements	O
to	O
the	O
Ethernet	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
communication	O
protocol	O
for	O
use	O
in	O
data	B-Operating_System
center	I-Operating_System
environments	O
,	O
in	O
particular	O
for	O
use	O
with	O
clustering	O
and	O
storage	O
area	O
networks	O
.	O
</s>
<s>
Ethernet	O
is	O
the	O
primary	O
network	O
protocol	O
in	O
data	B-Operating_System
centers	I-Operating_System
for	O
computer-to-computer	O
communications	O
.	O
</s>
<s>
However	O
,	O
Ethernet	O
is	O
designed	O
to	O
be	O
a	O
best-effort	O
network	O
that	O
may	O
experience	O
packet	B-Protocol
loss	I-Protocol
when	O
the	O
network	O
or	O
devices	O
are	O
busy	O
.	O
</s>
<s>
In	O
IP	B-Protocol
networks	O
,	O
transport	O
reliability	O
under	O
the	O
end-to-end	B-Application
principle	I-Application
is	O
the	O
responsibility	O
of	O
the	O
transport	O
protocols	O
,	O
such	O
as	O
the	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	O
)	O
.	O
</s>
<s>
A	O
primary	O
motivation	O
is	O
the	O
sensitivity	O
of	O
Fibre	B-Protocol
Channel	I-Protocol
over	I-Protocol
Ethernet	I-Protocol
to	O
frame	O
loss	O
.	O
</s>
<s>
The	O
higher	O
level	O
goal	O
is	O
to	O
use	O
a	O
single	O
set	O
of	O
Ethernet	O
physical	O
devices	O
or	O
adapters	O
for	O
computers	O
to	O
talk	O
to	O
a	O
Storage	O
Area	O
Network	O
,	O
Local	B-General_Concept
Area	I-General_Concept
network	I-General_Concept
and	O
InfiniBand	B-Architecture
fabric	O
.	O
</s>
<s>
DCB	O
aims	O
,	O
for	O
selected	O
traffic	O
,	O
to	O
eliminate	O
loss	O
due	O
to	O
queue	O
overflow	O
(	O
sometimes	O
called	O
lossless	B-Protocol
Ethernet	I-Protocol
)	O
and	O
to	O
be	O
able	O
to	O
allocate	O
bandwidth	O
on	O
links	O
.	O
</s>
<s>
Enabling	O
DCB	O
broadly	O
on	O
arbitrary	O
networks	O
with	O
irregular	O
topologies	O
and	O
without	O
special	O
routing	O
may	O
cause	O
deadlocks	O
,	O
large	O
buffering	O
delays	O
,	O
unfairness	O
and	O
head-of-line	B-Protocol
blocking	I-Protocol
.	O
</s>
<s>
Different	O
terms	O
have	O
been	O
used	O
to	O
market	O
products	O
based	O
on	O
data	B-Protocol
center	I-Protocol
bridging	I-Protocol
standards	O
:	O
</s>
<s>
Data	B-Protocol
Center	I-Protocol
Ethernet	I-Protocol
(	O
DCE	O
)	O
was	O
a	O
term	O
trademarked	O
by	O
Brocade	O
Communications	O
Systems	O
in	O
2007	O
but	O
abandoned	O
by	O
request	O
in	O
2008	O
.	O
</s>
<s>
DCE	O
referred	O
to	O
Ethernet	O
enhancements	O
for	O
the	O
Data	B-Protocol
Center	I-Protocol
Bridging	I-Protocol
standards	O
,	O
and	O
also	O
including	O
a	O
Layer	O
2	O
Multipathing	O
implementation	O
based	O
on	O
the	O
IETF	O
's	O
Transparent	B-Protocol
Interconnection	I-Protocol
of	I-Protocol
Lots	I-Protocol
of	I-Protocol
Links	I-Protocol
(	O
TRILL	B-Protocol
)	O
standard	O
.	O
</s>
<s>
Convergence	O
Enhanced	O
Ethernet	O
or	O
Converged	B-Protocol
Enhanced	I-Protocol
Ethernet	I-Protocol
(	O
CEE	O
)	O
was	O
defined	O
from	O
2008	O
through	O
January	O
2009	O
by	O
group	O
of	O
including	O
Broadcom	O
,	O
Brocade	O
Communications	O
Systems	O
,	O
Cisco	O
Systems	O
,	O
Emulex	O
,	O
HP	O
,	O
IBM	O
,	O
Juniper	O
Networks	O
,	O
QLogic	O
.	O
</s>
<s>
The	O
ad-hoc	O
group	O
formed	O
to	O
create	O
proposals	O
for	O
enhancements	O
that	O
enable	O
networking	O
protocol	O
convergence	O
over	O
Ethernet	O
,	O
specially	O
Fibre	B-Architecture
Channel	I-Architecture
.	O
</s>
<s>
Enhanced	B-Algorithm
Transmission	I-Algorithm
Selection	I-Algorithm
(	O
ETS	O
)	O
:	O
provides	O
a	O
common	O
management	O
framework	O
for	O
the	O
assignment	O
of	O
bandwidth	O
to	O
frame	O
priorities	O
.	O
</s>
<s>
Data	B-Protocol
Center	I-Protocol
Bridging	I-Protocol
Capabilities	O
Exchange	O
Protocol	O
(	O
DCBX	O
)	O
:	O
a	O
discovery	O
and	O
capability	O
exchange	O
protocol	O
that	O
is	O
used	O
for	O
conveying	O
capabilities	O
and	O
configuration	O
of	O
the	O
above	O
features	O
between	O
neighbors	O
to	O
ensure	O
consistent	O
configuration	O
across	O
the	O
network	O
.	O
</s>
<s>
This	O
protocol	O
leverages	O
functionality	O
provided	O
by	O
(	O
LLDP	B-Protocol
)	O
.	O
</s>
<s>
The	O
IETF	O
TRILL	B-Protocol
(	O
Transparent	B-Protocol
Interconnection	I-Protocol
of	I-Protocol
Lots	I-Protocol
of	I-Protocol
Links	I-Protocol
)	O
standard	O
provides	O
least	O
cost	O
pair-wise	O
data	O
forwarding	O
without	O
configuration	O
in	O
multi-hop	O
networks	O
with	O
arbitrary	O
topology	O
,	O
safe	O
forwarding	O
even	O
during	O
periods	O
of	O
temporary	O
loops	O
,	O
and	O
support	O
for	O
multipathing	O
of	O
both	O
unicast	O
and	O
multicast	O
traffic	O
.	O
</s>
<s>
TRILL	B-Protocol
accomplishes	O
this	O
by	O
using	O
IS-IS	B-Protocol
(	O
Intermediate	B-Protocol
System	I-Protocol
to	I-Protocol
Intermediate	I-Protocol
System	I-Protocol
)	O
link-state	O
routing	O
and	O
by	O
encapsulating	O
traffic	O
using	O
a	O
header	O
that	O
includes	O
a	O
hop	O
count	O
.	O
</s>
<s>
TRILL	B-Protocol
supports	O
VLANs	O
and	O
frame	O
priorities	O
.	O
</s>
<s>
Devices	O
that	O
implement	O
TRILL	B-Protocol
are	O
called	O
RBridges	O
.	O
</s>
<s>
IEEE	B-Protocol
802.1aq	I-Protocol
specifies	O
shortest	B-Protocol
path	I-Protocol
bridging	I-Protocol
of	O
unicast	O
and	O
multicast	O
Ethernet	O
frames	O
,	O
to	O
calculate	O
multiple	O
active	O
topologies	O
(	O
virtual	O
LANs	B-General_Concept
)	O
that	O
can	O
share	O
learned	O
station	O
location	O
information	O
.	O
</s>
<s>
SPBM	O
by	O
virtue	O
of	O
its	O
MACinMAC	O
encapsulation	O
is	O
more	O
suitable	O
for	O
a	O
large	O
data	B-Operating_System
centre	I-Operating_System
than	O
SPBV	O
.	O
</s>
<s>
802.1aq	B-Protocol
defines	O
16	O
tunable	O
multipath	O
options	O
as	O
part	O
of	O
the	O
base	O
protocol	O
,	O
with	O
an	O
extensible	O
multipathing	O
mechanism	O
to	O
allow	O
many	O
more	O
multipath	O
variations	O
in	O
the	O
future	O
.	O
</s>
<s>
802.1aq	B-Protocol
supports	O
the	O
dynamic	O
creation	O
of	O
virtual	O
LAN	B-General_Concept
's	O
that	O
interconnect	O
all	O
members	O
with	O
symmetric	O
shortest	O
path	O
routes	O
.	O
</s>
<s>
The	O
virtual	O
LANs	B-General_Concept
can	O
be	O
deterministically	O
assigned	O
to	O
the	O
different	O
multi	O
paths	O
providing	O
a	O
degree	O
of	O
traffic	O
engineering	O
in	O
addition	O
to	O
multipathing	O
and	O
can	O
grow	O
or	O
shrink	O
with	O
simple	O
membership	O
changes	O
.	O
</s>
<s>
802.1aq	B-Protocol
is	O
fully	O
backward	O
compatible	O
with	O
all	O
802.1	O
protocols	O
.	O
</s>
<s>
802.1aq	B-Protocol
became	O
an	O
IEEE	O
standard	O
in	O
April	O
2012	O
.	O
</s>
<s>
Fibre	B-Protocol
Channel	I-Protocol
over	I-Protocol
Ethernet	I-Protocol
:	O
This	O
project	O
utilizes	O
existing	O
Fibre	B-Architecture
Channel	I-Architecture
protocols	O
to	O
run	O
on	O
Ethernet	O
to	O
enable	O
servers	O
to	O
have	O
access	O
to	O
Fibre	B-Architecture
Channel	I-Architecture
storage	O
via	O
Ethernet	O
.	O
</s>
<s>
While	O
iSCSI	B-Protocol
was	O
available	O
,	O
it	O
depends	O
on	O
TCP/IP	O
and	O
there	O
was	O
a	O
desire	O
to	O
support	O
storage	O
traffic	O
at	O
layer	O
2	O
.	O
</s>
<s>
This	O
gave	O
rise	O
to	O
the	O
development	O
of	O
the	O
FCoE	B-Protocol
protocol	O
,	O
which	O
needed	O
reliable	O
Ethernet	O
transport	O
.	O
</s>
<s>
These	O
new	O
protocols	O
required	O
new	O
hardware	O
and	O
software	O
in	O
both	O
the	O
network	O
and	O
the	O
network	B-Protocol
interface	I-Protocol
controller	I-Protocol
.	O
</s>
