<s>
A	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
(	O
LAN	B-General_Concept
)	O
is	O
a	O
computer	B-Architecture
network	I-Architecture
that	O
interconnects	O
computers	O
within	O
a	O
limited	O
area	O
such	O
as	O
a	O
residence	O
,	O
school	O
,	O
laboratory	O
,	O
university	O
campus	O
or	O
office	O
building	O
.	O
</s>
<s>
By	O
contrast	O
,	O
a	O
wide	O
area	O
network	O
(	O
WAN	O
)	O
not	O
only	O
covers	O
a	O
larger	O
geographic	O
distance	O
,	O
but	O
also	O
generally	O
involves	O
leased	B-Architecture
telecommunication	I-Architecture
circuits	I-Architecture
.	O
</s>
<s>
Ethernet	O
and	O
Wi-Fi	O
are	O
the	O
two	O
most	O
common	O
technologies	O
in	O
use	O
for	O
local	B-General_Concept
area	I-General_Concept
networks	I-General_Concept
.	O
</s>
<s>
Historical	O
network	O
technologies	O
include	O
ARCNET	B-Protocol
,	O
Token	B-Device
Ring	I-Device
and	O
AppleTalk	B-Application
.	O
</s>
<s>
A	O
number	O
of	O
experimental	O
and	O
early	O
commercial	O
LAN	B-General_Concept
technologies	O
were	O
developed	O
in	O
the	O
1970s	O
.	O
</s>
<s>
Cambridge	B-General_Concept
Ring	I-General_Concept
was	O
developed	O
at	O
Cambridge	O
University	O
starting	O
in	O
1974	O
.	O
</s>
<s>
ARCNET	B-Protocol
was	O
developed	O
by	O
Datapoint	O
Corporation	O
in	O
1976	O
and	O
announced	O
in	O
1977	O
.	O
</s>
<s>
In	O
1979	O
,	O
the	O
Electronic	O
voting	O
systems	O
for	O
the	O
European	O
Parliament	O
was	O
the	O
first	O
installation	O
of	O
a	O
LAN	B-General_Concept
connecting	O
hundreds	O
(	O
420	O
)	O
of	O
microprocessor-controlled	O
voting	O
terminals	O
to	O
a	O
polling/selecting	O
central	O
unit	O
with	O
a	O
multidrop	B-Architecture
bus	I-Architecture
with	O
Master/slave	B-Operating_System
(	O
technology	O
)	O
arbitration	O
.	O
</s>
<s>
The	O
development	O
and	O
proliferation	O
of	O
personal	B-Device
computers	I-Device
using	O
the	O
CP/M	B-Application
operating	I-Application
system	I-Application
in	O
the	O
late	O
1970s	O
,	O
and	O
later	O
DOS-based	O
systems	O
starting	O
in	O
1981	O
,	O
meant	O
that	O
many	O
sites	O
grew	O
to	O
dozens	O
or	O
even	O
hundreds	O
of	O
computers	O
.	O
</s>
<s>
The	O
initial	O
driving	O
force	O
for	O
networking	O
was	O
to	O
share	O
storage	B-General_Concept
and	O
printers	O
,	O
both	O
of	O
which	O
were	O
expensive	O
at	O
the	O
time	O
.	O
</s>
<s>
There	O
was	O
much	O
enthusiasm	O
for	O
the	O
concept	O
,	O
and	O
for	O
several	O
years	O
,	O
from	O
about	O
1983	O
onward	O
,	O
computer	O
industry	O
pundits	O
habitually	O
declared	O
the	O
coming	O
year	O
to	O
be	O
,	O
"	O
The	O
year	O
of	O
the	O
LAN	B-General_Concept
"	O
.	O
</s>
<s>
In	O
practice	O
,	O
the	O
concept	O
was	O
marred	O
by	O
the	O
proliferation	O
of	O
incompatible	O
physical	B-Application
layer	I-Application
and	O
network	O
protocol	O
implementations	O
,	O
and	O
a	O
plethora	O
of	O
methods	O
of	O
sharing	O
resources	O
.	O
</s>
<s>
Typically	O
,	O
each	O
vendor	O
would	O
have	O
its	O
own	O
type	O
of	O
network	B-Protocol
card	I-Protocol
,	O
cabling	O
,	O
protocol	O
,	O
and	O
network	B-Protocol
operating	I-Protocol
system	I-Protocol
.	O
</s>
<s>
A	O
solution	O
appeared	O
with	O
the	O
advent	O
of	O
Novell	B-Operating_System
NetWare	I-Operating_System
which	O
provided	O
even-handed	O
support	O
for	O
dozens	O
of	O
competing	O
card	O
and	O
cable	O
types	O
,	O
and	O
a	O
much	O
more	O
sophisticated	O
operating	O
system	O
than	O
most	O
of	O
its	O
competitors	O
.	O
</s>
<s>
Of	O
the	O
competitors	O
to	O
NetWare	B-Operating_System
,	O
only	O
Banyan	B-Operating_System
Vines	I-Operating_System
had	O
comparable	O
technical	O
strengths	O
,	O
but	O
Banyan	O
never	O
gained	O
a	O
secure	O
base	O
.	O
</s>
<s>
3Com	O
produced	O
3+Share	B-General_Concept
and	O
Microsoft	O
produced	O
MS-Net	B-Application
.	O
</s>
<s>
These	O
then	O
formed	O
the	O
basis	O
for	O
collaboration	O
between	O
Microsoft	O
and	O
3Com	O
to	O
create	O
a	O
simple	O
network	B-Protocol
operating	I-Protocol
system	I-Protocol
LAN	B-Algorithm
Manager	I-Algorithm
and	O
its	O
cousin	O
,	O
IBM	O
's	O
LAN	B-Operating_System
Server	I-Operating_System
.	O
</s>
<s>
None	O
of	O
these	O
enjoyed	O
any	O
lasting	O
success	O
;	O
Netware	B-Operating_System
dominated	O
the	O
personal	B-Device
computer	I-Device
LAN	B-General_Concept
business	O
from	O
early	O
after	O
its	O
introduction	O
in	O
1983	O
until	O
the	O
mid-1990s	O
when	O
Microsoft	O
introduced	O
Windows	B-Device
NT	I-Device
.	O
</s>
<s>
In	O
1983	O
,	O
TCP/IP	B-Protocol
was	O
first	O
shown	O
capable	O
of	O
supporting	O
actual	O
defense	O
department	O
applications	O
on	O
a	O
Defense	O
Communication	O
Agency	O
LAN	B-General_Concept
testbed	O
located	O
at	O
Reston	O
,	O
Virginia	O
.	O
</s>
<s>
The	O
TCP/IP	B-Protocol
-based	O
LAN	B-General_Concept
successfully	O
supported	O
Telnet	B-Protocol
,	O
FTP	B-Protocol
,	O
and	O
a	O
Defense	O
Department	O
teleconferencing	O
application	O
.	O
</s>
<s>
This	O
demonstrated	O
the	O
feasibility	O
of	O
employing	O
TCP/IP	B-Protocol
LANs	B-General_Concept
to	O
interconnect	O
Worldwide	O
Military	O
Command	O
and	O
Control	O
System	O
(	O
WWMCCS	O
)	O
computers	O
at	O
command	O
centers	O
throughout	O
the	O
United	O
States	O
.	O
</s>
<s>
During	O
the	O
same	O
period	O
,	O
Unix	B-Device
workstations	I-Device
were	O
using	O
TCP/IP	B-Protocol
networking	O
.	O
</s>
<s>
Although	O
the	O
workstation	B-Device
market	O
segment	O
is	O
now	O
much	O
reduced	O
,	O
the	O
technologies	O
developed	O
in	O
the	O
area	O
continue	O
to	O
be	O
influential	O
on	O
the	O
Internet	O
and	O
in	O
all	O
forms	O
of	O
networking	O
—	O
and	O
the	O
TCP/IP	B-Protocol
protocol	I-Protocol
has	O
replaced	O
IPX	B-Protocol
,	O
AppleTalk	B-Application
,	O
NBF	B-Protocol
,	O
and	O
other	O
protocols	O
used	O
by	O
the	O
early	O
PC	B-General_Concept
LANs	I-General_Concept
.	O
</s>
<s>
In	O
1979	O
,	O
the	O
Electronic	O
voting	O
systems	O
for	O
the	O
European	O
Parliament	O
was	O
using	O
10	O
kilometers	O
of	O
simple	O
unshielded	O
twisted	O
pair	O
category	B-Protocol
3	I-Protocol
cable	I-Protocol
—	O
the	O
same	O
cable	O
used	O
for	O
telephone	O
systems	O
—	O
installed	O
inside	O
the	O
benches	O
of	O
the	O
European	O
Parliament	O
Hemicycles	O
in	O
Strasbourg	O
and	O
Luxembourg	O
.	O
</s>
<s>
Shielded	O
twisted	O
pair	O
was	O
used	O
in	O
IBM	O
's	O
Token	B-Device
Ring	I-Device
LAN	B-General_Concept
implementation	O
.	O
</s>
<s>
In	O
1984	O
,	O
StarLAN	B-Protocol
showed	O
the	O
potential	O
of	O
simple	O
unshielded	O
twisted	O
pair	O
by	O
using	O
category	B-Protocol
3	I-Protocol
cable	I-Protocol
—	O
the	O
same	O
cable	O
used	O
for	O
telephone	O
systems	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
development	O
of	O
10BASE-T	B-Protocol
(	O
and	O
its	B-Protocol
twisted-pair	I-Protocol
successors	I-Protocol
)	O
and	O
structured	O
cabling	O
which	O
is	O
still	O
the	O
basis	O
of	O
most	O
commercial	O
LANs	B-General_Concept
today	O
.	O
</s>
<s>
While	O
optical	O
fiber	O
cable	O
is	O
common	O
for	O
links	O
between	O
network	B-Protocol
switches	I-Protocol
,	O
use	O
of	O
fiber	B-Architecture
to	I-Architecture
the	I-Architecture
desktop	I-Architecture
is	O
rare	O
.	O
</s>
<s>
In	O
a	O
wireless	B-Architecture
LAN	I-Architecture
,	O
users	O
have	O
unrestricted	O
movement	O
within	O
the	O
coverage	O
area	O
.	O
</s>
<s>
Most	O
wireless	B-Architecture
LANs	I-Architecture
use	O
Wi-Fi	O
as	O
wireless	O
adapters	O
are	O
typically	O
integrated	O
into	O
smartphones	B-Application
,	O
tablet	B-Device
computers	I-Device
and	O
laptops	B-Device
.	O
</s>
<s>
Guests	O
are	O
often	O
offered	O
Internet	O
access	O
via	O
a	O
hotspot	B-Application
service	O
.	O
</s>
<s>
Network	B-Architecture
topology	I-Architecture
describes	O
the	O
layout	O
of	O
interconnections	O
between	O
devices	O
and	O
network	O
segments	O
.	O
</s>
<s>
At	O
the	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
and	O
physical	B-Application
layer	I-Application
,	O
a	O
wide	O
variety	O
of	O
LAN	B-Architecture
topologies	I-Architecture
have	O
been	O
used	O
,	O
including	O
ring	B-Architecture
,	O
bus	B-Architecture
,	O
mesh	B-Architecture
and	O
star	B-Architecture
.	O
</s>
<s>
Simple	O
LANs	B-General_Concept
generally	O
consist	O
of	O
cabling	O
and	O
one	O
or	O
more	O
switches	O
.	O
</s>
<s>
A	O
switch	B-Protocol
can	O
be	O
connected	O
to	O
a	O
router	B-Protocol
,	O
cable	B-Device
modem	I-Device
,	O
or	O
ADSL	B-Device
modem	I-Device
for	O
Internet	O
access	O
.	O
</s>
<s>
A	O
LAN	B-General_Concept
can	O
include	O
a	O
wide	O
variety	O
of	O
other	O
network	O
devices	O
such	O
as	O
firewalls	B-Application
,	O
load	B-Application
balancers	I-Application
,	O
and	O
network	O
intrusion	O
detection	O
.	O
</s>
<s>
Advanced	O
LANs	B-General_Concept
are	O
characterized	O
by	O
their	O
use	O
of	O
redundant	O
links	O
with	O
switches	O
using	O
the	O
spanning	B-Protocol
tree	I-Protocol
protocol	I-Protocol
to	O
prevent	O
loops	O
,	O
their	O
ability	O
to	O
manage	O
differing	O
traffic	O
types	O
via	O
quality	O
of	O
service	O
(	O
QoS	O
)	O
,	O
and	O
their	O
ability	O
to	O
segregate	O
traffic	O
with	O
VLANs	B-General_Concept
.	O
</s>
<s>
At	O
the	O
higher	O
network	O
layers	O
,	O
protocols	O
such	O
as	O
NetBIOS	B-Protocol
,	O
IPX/SPX	B-Protocol
,	O
AppleTalk	B-Application
and	O
others	O
were	O
once	O
common	O
,	O
but	O
the	O
Internet	B-Protocol
protocol	I-Protocol
suite	I-Protocol
(	O
TCP/IP	B-Protocol
)	O
has	O
prevailed	O
as	O
the	O
standard	O
of	O
choice	O
.	O
</s>
<s>
LANs	B-General_Concept
can	O
maintain	O
connections	O
with	O
other	O
LANs	B-General_Concept
via	O
leased	B-Architecture
lines	I-Architecture
,	O
leased	O
services	O
,	O
or	O
across	O
the	O
Internet	O
using	O
virtual	B-Application
private	I-Application
network	I-Application
technologies	O
.	O
</s>
<s>
Depending	O
on	O
how	O
the	O
connections	O
are	O
established	O
and	O
secured	O
,	O
and	O
the	O
distance	O
involved	O
,	O
such	O
linked	O
LANs	B-General_Concept
may	O
also	O
be	O
classified	O
as	O
a	O
metropolitan	O
area	O
network	O
(	O
MAN	O
)	O
or	O
a	O
wide	O
area	O
network	O
(	O
WAN	O
)	O
.	O
</s>
