<s>
A	O
media	B-Device
access	I-Device
unit	I-Device
(	O
MAU	O
)	O
,	O
also	O
known	O
as	O
a	O
multistation	B-Device
access	I-Device
unit	I-Device
(	O
MAU	O
or	O
MSAU	B-Device
)	O
,	O
is	O
a	O
device	O
to	O
attach	O
multiple	O
network	O
stations	O
in	O
a	O
star	B-Architecture
topology	I-Architecture
as	O
a	O
Token	B-Device
Ring	I-Device
network	I-Device
,	O
internally	O
wired	O
to	O
connect	O
the	O
stations	O
into	O
a	O
logical	O
ring	O
(	O
generally	O
passive	O
i.e.	O
</s>
<s>
non-switched	O
and	O
unmanaged	O
;	O
however	O
managed	O
Token	B-Device
Ring	I-Device
MAUs	O
do	O
exist	O
in	O
the	O
form	O
of	O
CAUs	O
,	O
or	O
Controlled	O
Access	O
Units	O
)	O
.	O
</s>
<s>
Passive	O
Token	B-Device
Ring	I-Device
was	O
an	O
active	O
IBM	O
networking	O
product	O
in	O
the	O
1997	O
time-frame	O
,	O
after	O
which	O
it	O
was	O
rapidly	O
displaced	O
by	O
switched	B-Protocol
networking	I-Protocol
.	O
</s>
<s>
The	O
majority	O
of	O
IBM-implemented	O
(	O
actual	O
)	O
passive	O
Token	B-Device
Ring	I-Device
MAUs	O
operated	O
without	O
the	O
requirement	O
of	O
power	O
;	O
instead	O
the	O
passive	O
MAU	O
used	O
a	O
series	O
of	O
relays	O
that	O
adjusted	O
themselves	O
as	O
data	O
is	O
passed	O
through	O
:	O
this	O
is	O
also	O
why	O
Token	B-Device
Ring	I-Device
generally	O
used	O
relays	O
to	O
terminate	O
disconnected	O
or	O
failed	O
ports	O
.	O
</s>
<s>
The	O
power-less	O
IBM	O
8228	O
Multistation	B-Device
Access	I-Device
Unit	I-Device
requires	O
a	O
special	O
'	O
Setup	O
Aid	O
 '	O
tool	O
to	O
re-align	O
the	O
relays	O
after	O
the	O
unit	O
has	O
been	O
moved	O
which	O
causes	O
them	O
to	O
be	O
in	O
incorrect	O
states	O
:	O
this	O
is	O
accomplished	O
by	O
a	O
9v	O
battery	O
sending	O
a	O
charge	O
to	O
snap	O
the	O
relays	O
back	O
in	O
a	O
proper	O
state	O
.	O
</s>
<s>
But	O
with	O
the	O
bandwidth	O
shared	O
by	O
all	O
stations	O
,	O
in	O
practice	O
separate	O
networks	O
spanning	O
smaller	O
areas	O
were	O
joined	O
using	O
bridges	B-General_Concept
.	O
</s>
<s>
Multistation	B-Device
Access	I-Device
Units	I-Device
contain	O
relays	O
to	O
short	O
out	O
non-operating	O
stations	O
.	O
</s>
<s>
The	O
loop	O
that	O
used	O
to	O
make	O
up	O
the	O
ring	O
of	O
the	O
token	B-Device
Ring	I-Device
is	O
now	O
integrated	O
into	O
this	O
device	O
.	O
</s>
<s>
In	O
Token	B-Device
Ring	I-Device
,	O
when	O
a	O
link	O
is	O
broken	O
in	O
the	O
ring	O
,	O
the	O
entire	O
network	O
goes	O
down	O
;	O
however	O
with	O
an	O
MAU	O
,	O
the	O
broken	O
circuit	O
is	O
closed	O
within	O
1ms	O
;	O
allowing	O
stations	O
on	O
the	O
ring	O
to	O
have	O
their	O
cords	O
unplugged	O
without	O
disabling	O
the	O
entire	O
network	O
.	O
</s>
