<s>
100BaseVG	B-Protocol
is	O
a	O
100Mbit/s	O
Ethernet	O
standard	O
specified	O
to	O
run	O
over	O
four	O
pairs	O
of	O
category	B-Protocol
3	I-Protocol
cable	I-Protocol
(	O
cable	O
also	O
known	O
as	O
voice	O
grade	O
,	O
hence	O
the	O
"	O
VG	O
"	O
)	O
.	O
</s>
<s>
It	O
is	O
also	O
called	O
100VG-AnyLAN	B-Protocol
because	O
it	O
was	O
defined	O
to	O
carry	O
both	O
Ethernet	O
and	O
Token	B-Device
Ring	I-Device
frame	O
types	O
.	O
</s>
<s>
100BaseVG	B-Protocol
was	O
originally	O
proposed	O
by	O
Hewlett-Packard	O
,	O
ratified	O
by	O
the	O
IEEE	O
in	O
1995	O
and	O
was	O
practically	O
extinct	O
by	O
1998	O
.	O
</s>
<s>
100BaseVG	B-Protocol
started	O
in	O
the	O
IEEE	O
802.3	O
committee	O
as	O
Fast	B-Protocol
Ethernet	I-Protocol
.	O
</s>
<s>
One	O
faction	O
wanted	O
to	O
keep	O
carrier-sense	O
multiple	O
access	O
with	O
collision	O
detection	O
(	O
CSMA/CD	O
)	O
in	O
order	O
to	O
keep	O
it	O
pure	O
Ethernet	O
,	O
even	O
though	O
the	O
collision	O
domain	O
problem	O
limited	O
the	O
distances	O
to	O
one	O
tenth	O
that	O
of	O
10BASE-T	B-Protocol
.	O
Another	O
faction	O
wanted	O
to	O
change	O
to	O
a	O
polling	O
architecture	O
from	O
the	O
hub	O
(	O
they	O
called	O
it	O
"	O
Demand	O
Priority	O
Protocol	O
"	O
)	O
in	O
order	O
to	O
maintain	O
the	O
10BASE-T	B-Protocol
distances	O
,	O
and	O
also	O
to	O
make	O
it	O
a	O
deterministic	O
protocol	O
.	O
</s>
<s>
Thus	O
,	O
the	O
IEEE	B-Protocol
802.12	I-Protocol
committee	O
was	O
formed	O
and	O
standardized	O
100BaseVG	B-Protocol
.	O
</s>
<s>
The	O
physical	B-Application
layer	I-Application
requires	O
four	O
twisted	O
pairs	O
of	O
"	O
voice-grade	O
"	O
cabling	O
for	O
a	O
link	O
,	O
so	O
category	B-Protocol
3	I-Protocol
cables	I-Protocol
or	O
better	O
can	O
be	O
used	O
.	O
</s>
<s>
This	O
makes	O
100BaseVG	B-Protocol
an	O
inherently	O
half-duplex	O
medium	O
like	O
e.g.	O
</s>
<s>
100BaseVG	B-Protocol
also	O
supports	O
full-duplex	O
operation	O
over	O
optical	B-Architecture
fiber	I-Architecture
or	O
over	O
two	O
pairs	O
of	O
shielded	O
twisted	O
pair	O
.	O
</s>
<s>
+Comparison	O
of	O
twisted-pair-based	B-Protocol
Ethernet	I-Protocol
physical	O
transport	O
layers	O
(	O
TP-PHYs	O
)	O
Name	O
Standard	O
Status	O
Speed	O
(	O
Mbit/s	O
)	O
Pairs	O
required	O
Lanes	O
per	O
direction	O
Bits	O
per	O
hertz	O
Line	B-Protocol
code	I-Protocol
Symbol	O
rate	O
per	O
lane	O
(	O
MBd	O
)	O
Bandwidth	O
Max	O
distance	O
(	O
m	O
)	O
Cable	O
Cable	O
rating	O
(	O
MHz	O
)	O
Usage	O
100	O
4	O
4	O
1	O
.	O
</s>
<s>
Instead	O
of	O
following	O
the	O
Fast	B-Protocol
Ethernet	I-Protocol
standard	O
for	O
twisted	O
pair	O
cabling	O
by	O
using	O
only	O
2	O
pairs	O
of	O
wires	O
,	O
100VG-AnyLAN	B-Protocol
used	O
all	O
four	O
pairs	O
in	O
either	O
Category	O
3	O
or	O
Category	O
5	O
twisted	O
pair	O
cable	O
.	O
</s>
<s>
The	O
design	O
goals	O
were	O
to	O
avoid	O
the	O
radio	O
frequency	O
radiation	O
emitted	O
at	O
the	O
higher	O
frequencies	O
required	O
by	O
Fast	B-Protocol
Ethernet	I-Protocol
and	O
to	O
leverage	O
existing	O
wiring	O
installations	O
of	O
Category	O
3	O
cabling	O
that	O
most	O
organizations	O
had	O
recently	O
installed	O
to	O
support	O
10	O
megabit	O
twisted-pair	B-Protocol
Ethernet	I-Protocol
.	O
</s>
<s>
When	O
Ethernet	O
became	O
Fast	B-Protocol
Ethernet	I-Protocol
,	O
it	O
continued	O
to	O
use	O
the	O
CSMA/CD	O
mechanism	O
to	O
manage	O
traffic	O
on	O
the	O
network	O
cable	O
.	O
</s>
<s>
100VG	B-Protocol
took	O
advantage	O
of	O
the	O
token	O
passing	O
concept	O
that	O
made	O
ARCNET	B-Protocol
and	O
Token	B-Device
Ring	I-Device
popular	O
in	O
order	O
to	O
provide	O
consistent	O
performance	O
no	O
matter	O
how	O
large	O
the	O
network	O
became	O
.	O
</s>
<s>
It	O
removed	O
the	O
token	O
passing	O
responsibility	O
from	O
the	O
wiring	O
and	O
network	O
nodes	O
and	O
placed	O
it	O
internal	O
to	O
the	O
100VG-AnyLAN	B-Protocol
hubs	O
.	O
</s>
<s>
Because	O
the	O
token	O
stayed	O
within	O
the	O
hub	O
,	O
it	O
did	O
not	O
have	O
to	O
traverse	O
long	O
cables	O
going	O
to	O
every	O
node	O
as	O
in	O
ARCNET	B-Protocol
and	O
Token	B-Device
Ring	I-Device
,	O
thereby	O
becoming	O
faster	O
than	O
those	O
other	O
deterministic	O
networking	O
standards	O
and	O
being	O
less	O
susceptible	O
to	O
cabling	O
problems	O
,	O
network	O
card	O
failures	O
,	O
and	O
line	O
interference	O
.	O
</s>
<s>
Real-life	O
load	O
testing	O
showed	O
100VG-AnyLAN	B-Protocol
reaching	O
95%	O
of	O
its	O
theoretical	O
network	O
speed	O
instead	O
of	O
about	O
45%	O
as	O
in	O
Fast	B-Protocol
Ethernet	I-Protocol
when	O
using	O
hubs	O
.	O
</s>
<s>
Fast	B-Protocol
Ethernet	I-Protocol
switches	O
were	O
not	O
commonplace	O
at	O
first	O
because	O
of	O
high	O
cost	O
and	O
limited	O
availability	O
so	O
,	O
initially	O
,	O
100VG	B-Protocol
had	O
a	O
significant	O
performance	O
advantage	O
.	O
</s>
