<s>
Host	B-Device
Embedded	I-Device
Controller	I-Device
Interface	I-Device
(	O
HECI	B-Device
)	O
is	O
technology	O
introduced	O
in	O
2006	O
used	O
for	O
Active	B-Application
Management	I-Application
Technology	I-Application
(	O
AMT	B-Application
)	O
in	O
Intel	O
chipsets	B-Device
that	O
support	O
Core	O
2	O
Duo	O
microprocessors	B-Architecture
.	O
</s>
<s>
The	O
HECI	B-Device
bus	B-General_Concept
allows	O
the	O
host	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	B-General_Concept
)	O
to	O
communicate	O
directly	O
with	O
the	O
Management	B-Device
Engine	I-Device
(	O
ME	O
)	O
integrated	O
in	O
the	O
chipset	B-Device
.	O
</s>
<s>
This	O
bi-directional	O
,	O
variable	O
data-rate	O
bus	B-General_Concept
enables	O
the	O
host	O
and	O
ME	O
to	O
communicate	O
system	O
management	O
information	O
and	O
events	O
in	O
a	O
standards-compliant	O
way	O
,	O
essentially	O
replacing	O
the	O
System	B-Algorithm
Management	I-Algorithm
Bus	I-Algorithm
(	O
SMBus	B-Algorithm
)	O
.	O
</s>
<s>
The	O
bus	B-General_Concept
consists	O
of	O
four	O
wires	O
:	O
a	O
request	O
and	O
grant	O
pair	O
along	O
with	O
a	O
serial	B-Protocol
transmit	O
and	O
receive	O
data	O
pair	O
.	O
</s>
<s>
Original	O
equipment	O
manufacturers	O
(	O
OEMs	O
)	O
have	O
historically	O
provided	O
active	B-Application
management	I-Application
technologies	I-Application
through	O
the	O
use	O
of	O
proprietary	B-Device
on-board	O
controllers	O
,	O
such	O
as	O
Baseboard	B-Device
Management	I-Device
Controllers	I-Device
.	O
</s>
<s>
These	O
solutions	O
typically	O
suffer	O
two	O
main	O
disadvantages	O
due	O
to	O
their	O
proprietary	B-Device
nature	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
the	O
inflexibility	O
is	O
even	O
greater	O
with	O
HECI	B-Device
due	O
to	O
coupling	O
HECI	B-Device
with	O
a	O
chipset	B-Device
,	O
and	O
having	O
to	O
redevelop	O
HECI	B-Device
software	O
for	O
each	O
different	O
chipset	B-Device
as	O
opposed	O
to	O
one	O
common	O
BMC	O
software	O
for	O
multiple	O
chipsets	B-Device
.	O
</s>
<s>
HECI	B-Device
and	O
the	O
previously	O
used	O
SMBus	B-Algorithm
have	O
the	O
following	O
aspects	O
in	O
common	O
:	O
the	O
Host	O
OS	B-General_Concept
is	O
able	O
to	O
control	O
system	O
management	O
devices	O
such	O
as	O
:	O
on-board	O
fan	O
controllers	O
,	O
remote	O
wake	O
devices	O
such	O
as	O
Wake-on-LAN	B-Protocol
,	O
power	O
supply	O
devices	O
such	O
as	O
Smart	B-Algorithm
Battery	I-Algorithm
Data	I-Algorithm
.	O
</s>
<s>
Builtin	O
HECI	B-Device
functionality	O
and	O
third-party	O
management	O
cards	O
can	O
allow	O
the	O
Host	O
OS	B-General_Concept
to	O
directly	O
initiate	O
management	O
events	O
(	O
such	O
as	O
remote	O
wake	O
,	O
or	O
,	O
out-of-band	O
throttling	O
to	O
decrease	O
thermal	O
and	O
power	O
profile	O
)	O
in	O
case	O
HECI	B-Device
is	O
supported	O
by	O
the	O
running	O
OS	B-General_Concept
.	O
</s>
<s>
Example	O
devices	O
are	O
network	B-Protocol
cards	I-Protocol
and	O
graphics	B-Device
cards	I-Device
.	O
</s>
<s>
Besides	O
that	O
,	O
both	O
HECI	B-Device
and	O
other	O
ME	O
technologies	O
are	O
chipset/ME	O
vendor-specific	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
assume	O
the	O
case	O
of	O
Wake-on-LAN	B-Protocol
.	O
</s>
<s>
Traditionally	O
,	O
the	O
OS	B-General_Concept
controls	O
Wake-on-LAN	B-Protocol
and	O
must	O
call	O
third-party	O
device	B-Application
drivers	I-Application
to	O
enable	O
support	O
on	O
a	O
network	B-Protocol
card	I-Protocol
.	O
</s>
<s>
With	O
the	O
HECI	B-Device
bus	B-General_Concept
,	O
the	O
host	O
is	O
able	O
to	O
assert	O
its	O
request	O
line	O
(	O
REQ#	O
)	O
,	O
the	O
ME	O
will	O
assert	O
its	O
grant	O
line	O
(	O
GNT#	O
)	O
,	O
and	O
the	O
host	O
can	O
send	O
its	O
message	O
using	O
its	O
serial	B-Protocol
transmit	O
signal	O
.	O
</s>
<s>
Upon	O
receipt	O
of	O
the	O
Wake-on-LAN	B-Protocol
enable	O
message	O
on	O
HECI	B-Device
,	O
the	O
ME	O
directly	O
enables	O
Wake-on-LAN	B-Protocol
in	O
the	O
integrated	O
(	O
or	O
externally	O
supported	O
)	O
network	O
device	O
.	O
</s>
<s>
Without	O
HECI	B-Device
drivers	O
in	O
the	O
OS	B-General_Concept
,	O
Wake-on-LAN	B-Protocol
functionality	O
is	O
lost	O
even	O
if	O
standard	O
network	O
drivers	O
would	O
be	O
able	O
to	O
enable	O
it	O
.	O
</s>
<s>
When	O
the	O
magic	O
wake	O
packet	O
is	O
received	O
by	O
the	O
LAN	O
device	O
,	O
the	O
encapsulated	O
data	O
is	O
passed	O
to	O
the	O
ME	O
,	O
which	O
has	O
its	O
own	O
TCP/IP	O
stack	O
and	O
can	O
decapsulate	O
the	O
packet	O
.	O
</s>
<s>
With	O
this	O
technology	O
,	O
the	O
magic	O
packet	O
may	O
be	O
encapsulated	O
in	O
TCP	B-Protocol
packets	O
thus	O
allowing	O
the	O
packet	O
to	O
traverse	O
network	O
infrastructures	O
via	O
routers	O
and	O
thereby	O
increasing	O
the	O
attack	O
surface	O
,	O
something	O
which	O
traditional	O
Wake-on-LAN	B-Protocol
does	O
not	O
enable	O
.	O
</s>
<s>
If	O
no	O
host/ME	O
interaction	O
is	O
needed	O
,	O
HECI	B-Device
and	O
other	O
ME	O
technologies	O
are	O
OS	B-General_Concept
independent	O
.	O
</s>
