<s>
Zigbee	B-Protocol
is	O
an	O
IEEE	O
802.15.4-based	O
specification	O
for	O
a	O
suite	O
of	O
high-level	O
communication	O
protocols	O
used	O
to	O
create	O
personal	B-General_Concept
area	I-General_Concept
networks	I-General_Concept
with	O
small	O
,	O
low-power	O
digital	O
radios	O
,	O
such	O
as	O
for	O
home	O
automation	O
,	O
medical	O
device	O
data	O
collection	O
,	O
and	O
other	O
low-power	O
low-bandwidth	O
needs	O
,	O
designed	O
for	O
small	O
scale	O
projects	O
which	O
need	O
wireless	O
connection	O
.	O
</s>
<s>
Hence	O
,	O
Zigbee	B-Protocol
is	O
a	O
low-power	O
,	O
low	O
data	O
rate	O
,	O
and	O
close	O
proximity	O
(	O
i.e.	O
,	O
personal	O
area	O
)	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
.	O
</s>
<s>
The	O
technology	O
defined	O
by	O
the	O
Zigbee	B-Protocol
specification	I-Protocol
is	O
intended	O
to	O
be	O
simpler	O
and	O
less	O
expensive	O
than	O
other	O
wireless	B-General_Concept
personal	I-General_Concept
area	I-General_Concept
networks	I-General_Concept
(	O
WPANs	B-General_Concept
)	O
,	O
such	O
as	O
Bluetooth	B-Protocol
or	O
more	O
general	O
wireless	O
networking	O
such	O
as	O
Wi-Fi	O
.	O
</s>
<s>
Zigbee	B-Protocol
devices	O
can	O
transmit	O
data	O
over	O
long	O
distances	O
by	O
passing	O
data	O
through	O
a	O
mesh	B-Architecture
network	I-Architecture
of	O
intermediate	O
devices	O
to	O
reach	O
more	O
distant	O
ones	O
.	O
</s>
<s>
Zigbee	B-Protocol
is	O
typically	O
used	O
in	O
low	O
data	O
rate	O
applications	O
that	O
require	O
long	O
battery	O
life	O
and	O
secure	O
networking	O
.	O
</s>
<s>
(	O
Zigbee	B-Protocol
networks	O
are	O
secured	O
by	O
128	O
bit	O
symmetric	B-Algorithm
encryption	I-Algorithm
keys	O
.	O
)	O
</s>
<s>
Zigbee	B-Protocol
has	O
a	O
defined	O
rate	O
of	O
up	O
to	O
250kbit/s	O
,	O
best	O
suited	O
for	O
intermittent	O
data	O
transmissions	O
from	O
a	O
sensor	O
or	O
input	O
device	O
.	O
</s>
<s>
Zigbee	B-Protocol
was	O
conceived	O
in	O
1998	O
,	O
standardized	O
in	O
2003	O
,	O
and	O
revised	O
in	O
2006	O
.	O
</s>
<s>
Zigbee	B-Protocol
is	O
a	O
low-power	O
wireless	O
mesh	B-Architecture
network	I-Architecture
standard	O
targeted	O
at	O
battery-powered	O
devices	O
in	O
wireless	O
control	O
and	O
monitoring	O
applications	O
.	O
</s>
<s>
Zigbee	B-Protocol
delivers	O
low-latency	O
communication	O
.	O
</s>
<s>
Zigbee	B-Protocol
chips	O
are	O
typically	O
integrated	O
with	O
radios	O
and	O
with	O
microcontrollers	B-Architecture
.	O
</s>
<s>
Zigbee	B-Protocol
operates	O
in	O
the	O
industrial	O
,	O
scientific	O
and	O
medical	O
(	O
ISM	B-Algorithm
)	O
radio	O
bands	O
:	O
2.4GHz	B-Algorithm
in	O
most	O
jurisdictions	O
worldwide	O
;	O
though	O
some	O
devices	O
also	O
use	O
784MHz	O
in	O
China	O
,	O
868MHz	O
in	O
Europe	O
and	O
915MHz	O
in	O
the	O
US	O
and	O
Australia	O
,	O
however	O
even	O
those	O
regions	O
and	O
countries	O
still	O
use	O
2.4GHz	B-Algorithm
for	O
most	O
commercial	O
Zigbee	B-Protocol
devices	O
for	O
home	O
use	O
.	O
</s>
<s>
Data	O
rates	O
vary	O
from	O
20kbit/s	O
(	O
868MHz	O
band	O
)	O
to	O
250kbit/s	O
(	O
2.4GHz	B-Algorithm
band	I-Algorithm
)	O
.	O
</s>
<s>
Zigbee	B-Protocol
builds	O
on	O
the	O
physical	B-Application
layer	I-Application
and	O
media	B-Protocol
access	I-Protocol
control	I-Protocol
defined	O
in	O
IEEE	O
standard	O
802.15.4	O
for	O
low-rate	O
wireless	B-General_Concept
personal	I-General_Concept
area	I-General_Concept
networks	I-General_Concept
(	O
WPANs	B-General_Concept
)	O
.	O
</s>
<s>
The	O
specification	O
includes	O
four	O
additional	O
key	O
components	O
:	O
network	B-Application
layer	I-Application
,	O
application	B-Application
layer	I-Application
,	O
Zigbee	B-Protocol
Device	O
Objects	O
(	O
ZDOs	O
)	O
and	O
manufacturer-defined	O
application	O
objects	O
.	O
</s>
<s>
The	O
Zigbee	B-Protocol
network	B-Application
layer	I-Application
natively	O
supports	O
both	O
star	B-Architecture
and	O
tree	B-Data_Structure
networks	I-Data_Structure
,	O
and	O
generic	O
mesh	B-Architecture
networking	I-Architecture
.	O
</s>
<s>
Within	O
star	B-Architecture
networks	I-Architecture
,	O
the	O
coordinator	O
must	O
be	O
the	O
central	O
node	O
.	O
</s>
<s>
Both	O
trees	O
and	O
meshes	O
allow	O
the	O
use	O
of	O
Zigbee	B-Protocol
routers	B-Protocol
to	O
extend	O
communication	O
at	O
the	O
network	O
level	O
.	O
</s>
<s>
Another	O
defining	O
feature	O
of	O
Zigbee	B-Protocol
is	O
facilities	O
for	O
carrying	O
out	O
secure	O
communications	O
,	O
protecting	O
establishment	O
and	O
transport	O
of	O
cryptographic	O
keys	O
,	O
ciphering	O
frames	O
,	O
and	O
controlling	O
device	O
.	O
</s>
<s>
Zigbee-style	O
self-organizing	O
ad	B-General_Concept
hoc	I-General_Concept
digital	I-General_Concept
radio	I-General_Concept
networks	I-General_Concept
were	O
conceived	O
in	O
the	O
1990s	O
.	O
</s>
<s>
The	O
IEEE	O
802.15.4-2003	O
Zigbee	B-Protocol
specification	I-Protocol
was	O
ratified	O
on	O
December	O
14	O
,	O
2004	O
.	O
</s>
<s>
The	O
Zigbee	B-Protocol
Alliance	O
announced	O
availability	O
of	O
Specification	O
1.0	O
on	O
June	O
13	O
,	O
2005	O
,	O
known	O
as	O
the	O
ZigBee	B-Protocol
2004	O
Specification	O
.	O
</s>
<s>
In	O
September	O
2006	O
,	O
the	O
Zigbee	B-Protocol
2006	O
Specification	O
was	O
announced	O
,	O
obsoleting	O
the	O
2004	O
stack	O
The	O
2006	O
specification	O
replaces	O
the	O
message	O
and	O
key	B-Application
–	I-Application
value	I-Application
pair	I-Application
structure	O
used	O
in	O
the	O
2004	O
stack	O
with	O
a	O
cluster	O
library	O
.	O
</s>
<s>
In	O
January	O
2017	O
,	O
Zigbee	B-Protocol
Alliance	O
renamed	O
the	O
library	O
to	O
Dotdot	O
and	O
announced	O
it	O
as	O
a	O
new	O
protocol	O
to	O
be	O
represented	O
by	O
an	O
emoticon	O
( ||	O
:	O
)	O
.	O
</s>
<s>
They	O
also	O
announced	O
it	O
will	O
now	O
additionally	O
run	O
over	O
other	O
network	O
types	O
using	O
Internet	B-Protocol
Protocol	I-Protocol
and	O
will	O
interconnect	O
with	O
other	O
standards	O
such	O
as	O
Thread	B-Protocol
.	O
</s>
<s>
Since	O
its	O
unveiling	O
,	O
Dotdot	O
has	O
functioned	O
as	O
the	O
default	O
application	B-Application
layer	I-Application
for	O
almost	O
all	O
Zigbee	B-Protocol
devices	O
.	O
</s>
<s>
Zigbee	B-Protocol
Pro	O
,	O
also	O
known	O
as	O
Zigbee	B-Protocol
2007	O
,	O
was	O
finalized	O
in	O
2007	O
.	O
</s>
<s>
A	O
Zigbee	B-Protocol
Pro	O
device	O
may	O
join	O
and	O
operate	O
on	O
a	O
legacy	O
Zigbee	B-Protocol
network	O
and	O
vice	O
versa	O
.	O
</s>
<s>
Due	O
to	O
differences	O
in	O
routing	B-Protocol
options	O
,	O
a	O
Zigbee	B-Protocol
Pro	O
device	O
must	O
become	O
a	O
non-routing	O
Zigbee	B-Protocol
End	O
Device	O
(	O
ZED	O
)	O
on	O
a	O
legacy	O
Zigbee	B-Protocol
network	O
,	O
and	O
a	O
legacy	O
Zigbee	B-Protocol
device	O
must	O
become	O
a	O
ZED	O
on	O
a	O
Zigbee	B-Protocol
Pro	O
network	O
.	O
</s>
<s>
It	O
operates	O
using	O
the	O
2.4GHz	B-Algorithm
ISM	B-Algorithm
band	I-Algorithm
,	O
and	O
adds	O
a	O
sub-GHz	O
band	O
.	O
</s>
<s>
Zigbee	B-Protocol
protocols	O
are	O
intended	O
for	O
embedded	O
applications	O
requiring	O
low	O
power	O
consumption	O
and	O
tolerating	O
low	O
data	O
rates	O
.	O
</s>
<s>
Zigbee	B-Protocol
is	O
not	O
for	O
situations	O
with	O
high	O
mobility	O
among	O
nodes	O
.	O
</s>
<s>
The	O
first	O
Zigbee	B-Protocol
application	O
profile	O
,	O
Home	O
Automation	O
,	O
was	O
announced	O
November	O
2	O
,	O
2007	O
.	O
</s>
<s>
It	O
is	O
an	O
enhancement	O
of	O
the	O
Zigbee	B-Protocol
Smart	O
Energy	O
version	O
1	O
specifications	O
.	O
</s>
<s>
Zigbee	B-Protocol
Smart	O
Energy	O
relies	O
on	O
Zigbee	B-Protocol
IP	O
,	O
a	O
network	B-Application
layer	I-Application
that	O
routes	O
standard	O
IPv6	O
traffic	O
over	O
IEEE	O
802.15.4	O
using	O
6LoWPAN	B-Protocol
header	O
compression	O
.	O
</s>
<s>
In	O
2009	O
,	O
the	O
Radio	O
Frequency	O
for	O
Consumer	O
Electronics	O
Consortium	O
(	O
RF4CE	B-Protocol
)	O
and	O
Zigbee	B-Protocol
Alliance	O
agreed	O
to	O
deliver	O
jointly	O
a	O
standard	O
for	O
radio	O
frequency	O
remote	O
controls	O
.	O
</s>
<s>
Zigbee	B-Protocol
RF4CE	B-Protocol
is	O
designed	O
for	O
a	O
broad	O
range	O
of	O
consumer	O
electronics	O
products	O
,	O
such	O
as	O
TVs	O
and	O
set-top	O
boxes	O
.	O
</s>
<s>
The	O
Zigbee	B-Protocol
RF4CE	B-Protocol
specification	O
uses	O
a	O
subset	O
of	O
Zigbee	B-Protocol
functionality	O
allowing	O
to	O
run	O
on	O
smaller	O
memory	O
configurations	O
in	O
lower-cost	O
devices	O
,	O
such	O
as	O
remote	O
control	O
of	O
consumer	O
electronics	O
.	O
</s>
<s>
The	O
radio	O
design	O
used	O
by	O
Zigbee	B-Protocol
has	O
few	O
analog	O
stages	O
and	O
uses	O
digital	O
circuits	O
wherever	O
possible	O
.	O
</s>
<s>
Products	O
that	O
integrate	O
the	O
radio	O
and	O
microcontroller	B-Architecture
into	O
a	O
single	O
module	O
are	O
available	O
.	O
</s>
<s>
The	O
Zigbee	B-Protocol
qualification	O
process	O
involves	O
a	O
full	O
validation	O
of	O
the	O
requirements	O
of	O
the	O
physical	B-Application
layer	I-Application
.	O
</s>
<s>
All	O
radios	O
derived	O
from	O
the	O
same	O
validated	O
semiconductor	B-Algorithm
mask	I-Algorithm
set	I-Algorithm
would	O
enjoy	O
the	O
same	O
RF	O
characteristics	O
.	O
</s>
<s>
Zigbee	B-Protocol
radios	O
have	O
very	O
tight	O
constraints	O
on	O
power	O
and	O
bandwidth	O
.	O
</s>
<s>
An	O
uncertified	O
physical	B-Application
layer	I-Application
that	O
malfunctions	O
can	O
increase	O
the	O
power	O
consumption	O
of	O
other	O
devices	O
on	O
a	O
Zigbee	B-Protocol
network	O
.	O
</s>
<s>
This	O
standard	O
specifies	O
operation	O
in	O
the	O
unlicensed	O
2.4	O
to	O
2.4835GHz	O
(	O
worldwide	O
)	O
,	O
902	O
to	O
928MHz	O
(	O
Americas	O
and	O
Australia	O
)	O
and	O
868	O
to	O
868.6MHz	O
(	O
Europe	O
)	O
ISM	B-Algorithm
bands	I-Algorithm
.	O
</s>
<s>
Sixteen	O
channels	O
are	O
allocated	O
in	O
the	O
2.4GHz	B-Algorithm
band	I-Algorithm
,	O
spaced	O
5MHz	O
apart	O
,	O
though	O
using	O
only	O
2MHz	O
of	O
bandwidth	O
each	O
.	O
</s>
<s>
The	O
radios	O
use	O
direct-sequence	B-Device
spread	I-Device
spectrum	I-Device
coding	O
,	O
which	O
is	O
managed	O
by	O
the	O
digital	O
stream	O
into	O
the	O
modulator	O
.	O
</s>
<s>
Binary	O
phase-shift	O
keying	O
(	O
BPSK	O
)	O
is	O
used	O
in	O
the	O
868	O
and	O
915MHz	O
bands	O
,	O
and	O
offset	O
quadrature	O
phase-shift	O
keying	O
(	O
OQPSK	O
)	O
that	O
transmits	O
two	O
bits	O
per	O
symbol	O
is	O
used	O
in	O
the	O
2.4GHz	B-Algorithm
band	I-Algorithm
.	O
</s>
<s>
The	O
raw	O
,	O
over-the-air	O
data	O
rate	O
is	O
250kbit/s	O
per	O
channel	O
in	O
the	O
2.4GHz	B-Algorithm
band	I-Algorithm
,	O
40kbit/s	O
per	O
channel	O
in	O
the	O
915MHz	O
band	O
,	O
and	O
20kbit/s	O
in	O
the	O
868MHz	O
band	O
.	O
</s>
<s>
For	O
indoor	O
applications	O
at	O
2.4GHz	B-Algorithm
transmission	O
distance	O
is	O
10	O
–	O
20m	O
,	O
depending	O
on	O
the	O
construction	O
materials	O
,	O
the	O
number	O
of	O
walls	O
to	O
be	O
penetrated	O
and	O
the	O
output	O
power	O
permitted	O
in	O
that	O
geographical	O
location	O
.	O
</s>
<s>
There	O
are	O
three	O
classes	O
of	O
Zigbee	B-Protocol
devices	O
:	O
</s>
<s>
Zigbee	B-Protocol
Coordinator	O
(	O
ZC	O
)	O
:	O
The	O
most	O
capable	O
device	O
,	O
the	O
coordinator	O
forms	O
the	O
root	O
of	O
the	O
network	O
tree	B-Data_Structure
and	O
may	O
bridge	O
to	O
other	O
networks	O
.	O
</s>
<s>
There	O
is	O
precisely	O
one	O
Zigbee	B-Protocol
coordinator	O
in	O
each	O
network	O
since	O
it	O
is	O
the	O
device	O
that	O
started	O
the	O
network	O
originally	O
(	O
the	O
Zigbee	B-Protocol
LightLink	O
specification	O
also	O
allows	O
operation	O
without	O
a	O
Zigbee	B-Protocol
coordinator	O
,	O
making	O
it	O
more	O
usable	O
for	O
off-the-shelf	O
home	O
products	O
)	O
.	O
</s>
<s>
Zigbee	B-Protocol
Router	O
(	O
ZR	O
)	O
:	O
As	O
well	O
as	O
running	O
an	O
application	O
function	O
,	O
router	O
devices	O
can	O
act	O
as	O
intermediate	O
routers	B-Protocol
,	O
passing	O
data	O
on	O
to	O
other	O
devices	O
.	O
</s>
<s>
These	O
types	O
of	O
Zigbee	B-Protocol
products	O
are	O
typically	O
mains-powered	O
so	O
they	O
are	O
always	O
available	O
on	O
the	O
network	O
.	O
</s>
<s>
Zigbee	B-Protocol
Router	O
devices	O
are	O
sometimes	O
called	O
Zigbee	B-Protocol
repeaters	O
or	O
Zigbee	B-Protocol
range	O
extenders	O
.	O
</s>
<s>
Zigbee	B-Protocol
End	O
Device	O
(	O
ZED	O
)	O
:	O
Contains	O
just	O
enough	O
functionality	O
to	O
talk	O
to	O
the	O
parent	O
node	O
(	O
either	O
the	O
coordinator	O
or	O
a	O
router	O
)	O
;	O
it	O
cannot	O
relay	O
data	O
from	O
other	O
devices	O
.	O
</s>
<s>
These	O
types	O
of	O
Zigbee	B-Protocol
device	O
products	O
are	O
often	O
battery-powered	O
.	O
</s>
<s>
The	O
current	O
Zigbee	B-Protocol
protocols	O
support	O
beacon-enabled	O
and	O
non-beacon-enabled	O
networks	O
.	O
</s>
<s>
In	O
this	O
type	O
of	O
network	O
,	O
Zigbee	B-Protocol
routers	B-Protocol
typically	O
have	O
their	O
receivers	O
continuously	O
active	O
,	O
requiring	O
additional	O
power	O
.	O
</s>
<s>
The	O
typical	O
example	O
of	O
a	O
heterogeneous	O
network	O
is	O
a	O
wireless	O
light	O
switch	O
:	O
The	O
Zigbee	B-Protocol
node	O
at	O
the	O
lamp	O
may	O
constantly	O
receive	O
since	O
it	O
is	O
reliably	O
powered	O
by	O
the	O
mains	O
supply	O
to	O
the	O
lamp	O
,	O
while	O
a	O
battery-powered	O
light	O
switch	O
would	O
remain	O
asleep	O
until	O
the	O
switch	O
is	O
thrown	O
.	O
</s>
<s>
In	O
such	O
a	O
network	O
the	O
lamp	O
node	O
will	O
be	O
at	O
least	O
a	O
Zigbee	B-Protocol
router	O
,	O
if	O
not	O
the	O
Zigbee	B-Protocol
coordinator	O
;	O
the	O
switch	O
node	O
is	O
typically	O
a	O
Zigbee	B-Protocol
end	O
device	O
.	O
</s>
<s>
In	O
beacon-enabled	O
networks	O
,	O
Zigbee	B-Protocol
routers	B-Protocol
transmit	O
periodic	O
beacons	O
to	O
confirm	O
their	O
presence	O
to	O
other	O
network	O
nodes	O
.	O
</s>
<s>
In	O
general	O
,	O
the	O
Zigbee	B-Protocol
protocols	O
minimize	O
the	O
time	O
the	O
radio	O
is	O
on	O
,	O
so	O
as	O
to	O
reduce	O
power	O
use	O
.	O
</s>
<s>
Except	O
for	O
Smart	O
Energy	O
Profile	O
2.0	O
,	O
Zigbee	B-Protocol
devices	O
are	O
required	O
to	O
conform	O
to	O
the	O
IEEE	O
802.15.4-2003	O
Low-rate	O
Wireless	B-General_Concept
Personal	I-General_Concept
Area	I-General_Concept
Network	I-General_Concept
(	O
LR-WPAN	O
)	O
standard	O
.	O
</s>
<s>
The	O
standard	O
specifies	O
the	O
lower	O
protocol	B-Protocol
layers	I-Protocol
—	O
the	O
physical	B-Application
layer	I-Application
(	O
PHY	O
)	O
,	O
and	O
the	O
media	B-Protocol
access	I-Protocol
control	I-Protocol
portion	O
of	O
the	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
.	O
</s>
<s>
The	O
main	O
functions	O
of	O
the	O
network	B-Application
layer	I-Application
are	O
to	O
ensure	O
correct	O
use	O
of	O
the	O
MAC	B-Protocol
sublayer	I-Protocol
and	O
provide	O
a	O
suitable	O
interface	O
for	O
use	O
by	O
the	O
next	O
upper	O
layer	O
,	O
namely	O
the	O
application	B-Application
layer	I-Application
.	O
</s>
<s>
The	O
network	B-Application
layer	I-Application
deals	O
with	O
network	O
functions	O
such	O
as	O
connecting	O
,	O
disconnecting	O
,	O
and	O
setting	O
up	O
networks	O
.	O
</s>
<s>
This	O
layer	O
makes	O
use	O
of	O
star	B-Architecture
,	O
mesh	O
and	O
tree	B-Data_Structure
topologies	I-Data_Structure
.	O
</s>
<s>
The	O
data	O
entity	O
of	O
the	O
transport	O
layer	O
creates	O
and	O
manages	O
protocol	B-Protocol
data	I-Protocol
units	I-Protocol
at	O
the	O
direction	O
of	O
the	O
application	B-Application
layer	I-Application
and	O
performs	O
routing	B-Protocol
according	O
to	O
the	O
current	O
topology	O
.	O
</s>
<s>
It	O
can	O
determine	O
whether	O
a	O
neighboring	O
device	O
belongs	O
to	O
the	O
network	O
and	O
discovers	O
new	O
neighbors	O
and	O
routers	B-Protocol
.	O
</s>
<s>
The	O
routing	B-Protocol
protocol	O
used	O
by	O
the	O
network	B-Application
layer	I-Application
is	O
AODV	B-Device
.	O
</s>
<s>
To	O
find	O
a	O
destination	O
device	O
,	O
AODV	B-Device
is	O
used	O
to	O
broadcast	B-Operating_System
a	O
route	O
request	O
to	O
all	O
of	O
its	O
neighbors	O
.	O
</s>
<s>
The	O
neighbors	O
then	O
broadcast	B-Operating_System
the	O
request	O
to	O
their	O
neighbors	O
and	O
onward	O
until	O
the	O
destination	O
is	O
reached	O
.	O
</s>
<s>
Once	O
the	O
destination	O
is	O
reached	O
,	O
a	O
route	O
reply	O
is	O
sent	O
via	O
unicast	B-Protocol
transmission	O
following	O
the	O
lowest	O
cost	O
path	O
back	O
to	O
the	O
source	O
.	O
</s>
<s>
Once	O
the	O
source	O
receives	O
the	O
reply	O
,	O
it	O
updates	O
its	O
routing	B-Protocol
table	O
with	O
the	O
destination	O
address	O
of	O
the	O
next	O
hop	O
in	O
the	O
path	O
and	O
the	O
associated	O
path	O
cost	O
.	O
</s>
<s>
The	O
application	B-Application
layer	I-Application
is	O
the	O
highest-level	O
layer	O
defined	O
by	O
the	O
specification	O
and	O
is	O
the	O
effective	O
interface	O
of	O
the	O
Zigbee	B-Protocol
system	O
to	O
its	O
end	O
users	O
.	O
</s>
<s>
It	O
comprises	O
the	O
majority	O
of	O
components	O
added	O
by	O
the	O
Zigbee	B-Protocol
specification	I-Protocol
:	O
both	O
ZDO	O
(	O
Zigbee	B-Protocol
device	O
object	O
)	O
and	O
its	O
management	O
procedures	O
,	O
together	O
with	O
application	O
objects	O
defined	O
by	O
the	O
manufacturer	O
,	O
are	O
considered	O
part	O
of	O
this	O
layer	O
.	O
</s>
<s>
It	O
is	O
responsible	O
for	O
providing	O
service	O
to	O
Zigbee	B-Protocol
device	O
profiles	O
.	O
</s>
<s>
The	O
ZDO	O
(	O
Zigbee	B-Protocol
device	O
object	O
)	O
,	O
a	O
protocol	O
in	O
the	O
Zigbee	B-Protocol
protocol	B-Protocol
stack	I-Protocol
,	O
is	O
responsible	O
for	O
overall	O
device	O
management	O
,	O
security	O
keys	O
,	O
and	O
policies	O
.	O
</s>
<s>
It	O
works	O
as	O
a	O
bridge	O
between	O
the	O
network	B-Application
layer	I-Application
and	O
the	O
other	O
elements	O
of	O
the	O
application	B-Application
layer	I-Application
:	O
it	O
keeps	O
up-to-date	O
binding	O
tables	O
in	O
the	O
form	O
of	O
a	O
database	O
,	O
which	O
can	O
be	O
used	O
to	O
find	O
appropriate	O
devices	O
depending	O
on	O
the	O
services	O
that	O
are	O
needed	O
and	O
those	O
the	O
different	O
devices	O
offer	O
.	O
</s>
<s>
As	O
the	O
union	O
between	O
both	O
specified	O
layers	O
,	O
it	O
also	O
routes	O
messages	O
across	O
the	O
layers	O
of	O
the	O
protocol	B-Protocol
stack	I-Protocol
.	O
</s>
<s>
The	O
focus	O
of	O
Zigbee	B-Protocol
is	O
to	O
distribute	O
work	O
among	O
many	O
different	O
devices	O
which	O
reside	O
within	O
individual	O
Zigbee	B-Protocol
nodes	O
which	O
in	O
turn	O
form	O
a	O
network	O
.	O
</s>
<s>
0	O
is	O
reserved	O
for	O
the	O
ZDO	O
data	O
interface	O
and	O
255	O
for	O
broadcast	B-Operating_System
;	O
the	O
241-254	O
range	O
is	O
not	O
currently	O
in	O
use	O
but	O
may	O
be	O
in	O
the	O
future	O
.	O
</s>
<s>
Two	O
services	O
are	O
available	O
for	O
application	O
objects	O
to	O
use	O
(	O
in	O
Zigbee	B-Protocol
1.0	O
)	O
:	O
</s>
<s>
The	O
key-value	B-Application
pair	I-Application
service	O
(	O
KVP	O
)	O
is	O
meant	O
for	O
configuration	O
purposes	O
.	O
</s>
<s>
Configuration	O
uses	O
XML	B-Protocol
.	O
</s>
<s>
The	O
message	O
service	O
is	O
designed	O
to	O
offer	O
a	O
general	O
approach	O
to	O
information	O
treatment	O
,	O
avoiding	O
the	O
necessity	O
to	O
adapt	O
application	B-Application
protocols	I-Application
and	O
potential	O
overhead	O
incurred	O
by	O
KVP	O
.	O
</s>
<s>
Addressing	O
is	O
also	O
part	O
of	O
the	O
application	B-Application
layer	I-Application
.	O
</s>
<s>
For	O
applications	O
to	O
communicate	O
,	O
the	O
devices	O
that	O
support	O
them	O
must	O
use	O
a	O
common	O
application	B-Application
protocol	I-Application
(	O
types	O
of	O
messages	O
,	O
formats	O
and	O
so	O
on	O
)	O
;	O
these	O
sets	O
of	O
conventions	O
are	O
grouped	O
in	O
profiles	O
.	O
</s>
<s>
When	O
the	O
network	O
address	O
is	O
known	O
,	O
the	O
IEEE	O
address	O
can	O
be	O
requested	O
using	O
unicast	B-Protocol
communication	O
.	O
</s>
<s>
When	O
it	O
is	O
not	O
,	O
petitions	O
are	O
broadcast	B-Operating_System
.	O
</s>
<s>
The	O
use	O
of	O
cluster	O
identifiers	O
enforces	O
the	O
binding	O
of	O
complementary	O
entities	O
using	O
the	O
binding	O
tables	O
,	O
which	O
are	O
maintained	O
by	O
Zigbee	B-Protocol
coordinators	O
,	O
as	O
the	O
table	O
must	O
always	O
be	O
available	O
within	O
a	O
network	O
and	O
coordinators	O
are	O
most	O
likely	O
to	O
have	O
a	O
permanent	O
power	O
supply	O
.	O
</s>
<s>
Besides	O
these	O
two	O
methods	O
,	O
broadcast	B-Operating_System
to	O
all	O
endpoints	O
in	O
a	O
device	O
is	O
available	O
,	O
and	O
group	O
addressing	O
is	O
used	O
to	O
communicate	O
with	O
groups	O
of	O
endpoints	O
belonging	O
to	O
a	O
specified	O
set	O
of	O
devices	O
.	O
</s>
<s>
As	O
one	O
of	O
its	O
defining	O
features	O
,	O
Zigbee	B-Protocol
provides	O
facilities	O
for	O
carrying	O
out	O
secure	O
communications	O
,	O
protecting	O
establishment	O
and	O
transport	O
of	O
cryptographic	O
keys	O
and	O
encrypting	O
data	O
.	O
</s>
<s>
The	O
Zigbee	B-Protocol
network	O
model	O
must	O
take	O
particular	O
care	O
of	O
security	O
considerations	O
,	O
as	O
ad	B-Protocol
hoc	I-Protocol
networks	I-Protocol
may	O
be	O
physically	O
accessible	O
to	O
external	O
devices	O
.	O
</s>
<s>
Within	O
the	O
protocol	B-Protocol
stack	I-Protocol
,	O
different	O
network	B-Application
layers	I-Application
are	O
not	O
cryptographically	O
separated	O
,	O
so	O
access	O
policies	O
are	O
needed	O
,	O
and	O
conventional	O
design	O
assumed	O
.	O
</s>
<s>
As	O
malicious	O
devices	O
may	O
exist	O
,	O
every	O
network	B-Application
layer	I-Application
payload	O
must	O
be	O
ciphered	O
,	O
so	O
unauthorized	O
traffic	O
can	O
be	O
immediately	O
cut	O
off	O
.	O
</s>
<s>
The	O
Zigbee	B-Protocol
security	O
architecture	O
is	O
based	O
on	O
CCM*	O
,	O
which	O
adds	O
encryption	O
-	O
and	O
integrity-only	O
features	O
to	O
CCM	B-Algorithm
mode	I-Algorithm
.	O
</s>
<s>
Zigbee	B-Protocol
uses	O
128-bit	O
keys	O
to	O
implement	O
its	O
security	O
mechanisms	O
.	O
</s>
<s>
A	O
key	O
can	O
be	O
associated	O
either	O
to	O
a	O
network	O
,	O
being	O
usable	O
by	O
Zigbee	B-Protocol
layers	O
and	O
the	O
MAC	B-Protocol
sublayer	I-Protocol
,	O
or	O
to	O
a	O
link	O
,	O
acquired	O
through	O
pre-installation	O
,	O
agreement	O
or	O
transport	O
.	O
</s>
<s>
Link	O
and	O
master	O
keys	O
are	O
only	O
visible	O
to	O
the	O
application	B-Application
layer	I-Application
.	O
</s>
<s>
The	O
security	O
architecture	O
is	O
distributed	O
among	O
the	O
network	B-Application
layers	I-Application
as	O
follows	O
:	O
</s>
<s>
The	O
MAC	B-Protocol
sublayer	I-Protocol
is	O
capable	O
of	O
single-hop	O
reliable	O
communications	O
.	O
</s>
<s>
The	O
network	B-Application
layer	I-Application
manages	O
routing	B-Protocol
,	O
processing	O
received	O
messages	O
and	O
is	O
capable	O
of	O
broadcasting	O
requests	O
.	O
</s>
<s>
If	O
available	O
,	O
outgoing	O
frames	O
use	O
the	O
appropriate	O
link	O
key	O
according	O
to	O
the	O
routing	B-Protocol
.	O
</s>
<s>
The	O
application	B-Application
layer	I-Application
offers	O
key	O
establishment	O
and	O
transport	O
services	O
to	O
both	O
ZDO	O
and	O
applications	O
.	O
</s>
<s>
According	O
to	O
the	O
German	O
computer	O
e-magazine	O
Heise	O
Online	O
,	O
Zigbee	B-Protocol
Home	O
Automation	O
1.2	O
is	O
using	O
fallback	O
keys	O
for	O
encryption	O
negotiation	O
which	O
are	O
known	O
and	O
cannot	O
be	O
changed	O
.	O
</s>
<s>
Network	O
simulators	O
,	O
like	O
ns-2	B-Language
,	O
OMNeT++	B-Application
,	O
OPNET	O
,	O
and	O
NetSim	O
can	O
be	O
used	O
to	O
simulate	O
IEEE	O
802.15.4	O
Zigbee	B-Protocol
networks	O
.	O
</s>
<s>
These	O
simulators	O
come	O
with	O
open	O
source	O
C	B-Language
or	O
C++	B-Language
libraries	B-Language
for	O
users	O
to	O
modify	O
.	O
</s>
