<s>
The	O
5-4-3	B-Protocol
rule	I-Protocol
,	O
also	O
referred	O
to	O
as	O
the	O
IEEE	O
way	O
,	O
is	O
a	O
design	O
guideline	O
for	O
Ethernet	O
computer	O
networks	O
covering	O
the	O
number	O
of	O
repeaters	O
and	O
segments	O
on	O
shared-medium	O
Ethernet	O
backbones	O
in	O
a	O
tree	B-Data_Structure
topology	I-Data_Structure
.	O
</s>
<s>
It	O
means	O
that	O
in	O
a	O
collision	B-Protocol
domain	I-Protocol
there	O
should	O
be	O
at	O
most	O
5	O
segments	O
tied	O
together	O
with	O
4	O
repeaters	O
,	O
with	O
up	O
to	O
3	O
mixing	O
segments	O
(	O
10BASE5	O
,	O
10BASE2	O
,	O
or	O
10BASE-FP	O
)	O
.	O
</s>
<s>
Link	O
segments	O
can	O
be	O
10BASE-T	B-Protocol
,	O
10BASE-FL	O
or	O
10BASE-FB	O
.	O
</s>
<s>
This	O
rule	O
is	O
also	O
designated	O
the	O
5-4-3-2-1	B-Protocol
rule	I-Protocol
with	O
there	O
being	O
two	O
link	O
segments	O
(	O
without	O
senders	O
)	O
and	O
one	O
collision	B-Protocol
domain	I-Protocol
.	O
</s>
<s>
An	O
alternate	O
configuration	O
rule	O
,	O
known	O
as	O
the	O
Ethernet	B-Protocol
way	I-Protocol
,	O
allows	O
2	O
repeaters	O
on	O
the	O
single	O
network	O
and	O
does	O
not	O
allow	O
any	O
hosts	O
on	O
the	O
connection	O
between	O
repeaters	O
.	O
</s>
<s>
The	O
rules	O
only	O
apply	O
to	O
shared-medium	O
Ethernet	B-Protocol
segments	I-Protocol
connected	O
by	O
repeaters	O
or	O
repeater	B-Protocol
hubs	I-Protocol
(	O
collisions	O
domains	O
)	O
and	O
FOIRL	O
links	O
.	O
</s>
<s>
The	O
rules	O
do	O
not	O
apply	O
to	O
switched	B-Protocol
Ethernet	I-Protocol
because	O
each	O
port	O
on	O
a	O
switch	O
constitutes	O
a	O
separate	O
collision	B-Protocol
domain	I-Protocol
.	O
</s>
<s>
According	O
to	O
the	O
original	O
Ethernet	O
protocol	O
,	O
a	O
signal	O
sent	O
out	O
over	O
the	O
collision	B-Protocol
domain	I-Protocol
must	O
reach	O
every	O
part	O
of	O
the	O
network	O
within	O
a	O
specified	O
length	O
of	O
time	O
.	O
</s>
<s>
The	O
5-4-3	B-Protocol
rule	I-Protocol
ensures	O
this	O
.	O
</s>
<s>
Each	O
segment	B-Protocol
and	O
repeater	O
that	O
a	O
signal	O
goes	O
through	O
adds	O
a	O
small	O
amount	O
of	O
time	O
to	O
the	O
process	O
,	O
so	O
the	O
rule	O
is	O
designed	O
to	O
minimize	O
transmission	O
times	O
of	O
the	O
signals	O
.	O
</s>
<s>
For	O
the	O
purposes	O
of	O
this	O
rule	O
,	O
a	O
segment	B-Protocol
is	O
in	O
accordance	O
with	O
the	O
IEEE	O
definition	O
:	O
an	O
electrical	O
connection	O
between	O
networked	O
devices	O
.	O
</s>
<s>
In	O
the	O
original	O
10BASE5	O
and	O
10BASE2	O
Ethernet	O
varieties	O
,	O
a	O
segment	B-Protocol
would	O
therefore	O
correspond	O
to	O
a	O
single	O
coax	O
cable	O
and	O
any	O
devices	O
tapped	O
into	O
it	O
–	O
a	O
mixing	O
segment	B-Protocol
.	O
</s>
<s>
On	O
modern	O
twisted-pair	B-Protocol
Ethernet	I-Protocol
,	O
a	O
network	B-Protocol
segment	I-Protocol
corresponds	O
to	O
the	O
individual	O
connection	O
between	O
end	B-Protocol
station	I-Protocol
to	O
network	O
equipment	O
or	O
the	O
connections	O
between	O
different	O
pieces	O
of	O
network	O
equipment	O
.	O
</s>
<s>
This	O
rule	O
divides	O
a	O
collision	B-Protocol
domain	I-Protocol
into	O
two	O
types	O
of	O
physical	O
segments	O
:	O
mixing	O
segments	O
,	O
and	O
link	O
segments	O
.	O
</s>
<s>
Link	O
segments	O
(	O
FOIRL	O
,	O
10BASE-T	B-Protocol
,	O
10BASE-FL	O
,	O
or	O
10BASE-FB	O
)	O
are	O
used	O
to	O
connect	O
the	O
network	O
's	O
repeaters	O
together	O
.	O
</s>
<s>
The	O
rule	O
mandates	O
that	O
there	O
can	O
only	O
be	O
a	O
maximum	O
of	O
five	O
segments	O
,	O
connected	O
through	O
four	O
repeaters	O
,	O
or	O
concentrators	B-Protocol
,	O
and	O
only	O
three	O
of	O
the	O
five	O
segments	O
may	O
be	O
mixing	O
segments	O
.	O
</s>
<s>
This	O
last	O
requirement	O
applies	O
only	O
to	O
10BASE5	O
,	O
10BASE2	O
,	O
and	O
10BASE-FP	O
Ethernet	B-Protocol
segments	I-Protocol
.	O
</s>
<s>
Too	O
many	O
bits	O
lost	O
meant	O
that	O
an	O
end	B-Protocol
node	I-Protocol
may	O
not	O
have	O
enough	O
preamble	O
bits	O
to	O
lock	O
on	O
and	O
the	O
entire	O
frame	O
would	O
be	O
missed	O
.	O
</s>
<s>
Various	O
repeaters	O
(	O
hubs	B-Protocol
)	O
may	O
use	O
slightly	O
different	O
implementations	O
and	O
operate	O
differently	O
.	O
</s>
<s>
applying	O
the	O
5-4-3	B-Protocol
rule	I-Protocol
)	O
.	O
</s>
<s>
In	O
a	O
lab	O
at	O
DEC	O
they	O
knew	O
how	O
many	O
bits	O
their	O
repeaters	O
would	O
lose	O
and	O
knowing	O
this	O
were	O
able	O
to	O
create	O
an	O
11	O
segment	B-Protocol
,	O
10	O
repeater	O
,	O
3	O
active	O
segment	B-Protocol
(	O
11-10-3	O
)	O
network	O
that	O
maintained	O
a	O
round	O
trip	O
delay	O
of	O
less	O
than	O
and	O
a	O
sufficient	O
number	O
of	O
preamble	O
bits	O
that	O
all	O
end	B-Protocol
nodes	I-Protocol
functioned	O
properly	O
.	O
</s>
