<s>
A	O
Medium	B-Protocol
Attachment	I-Protocol
Unit	I-Protocol
(	O
MAU	B-Protocol
)	O
is	O
a	O
transceiver	O
which	O
converts	O
signals	O
on	O
an	O
Ethernet	O
cable	O
to	O
and	O
from	O
Attachment	B-Protocol
Unit	I-Protocol
Interface	I-Protocol
(	O
AUI	B-Protocol
)	O
signals	O
.	O
</s>
<s>
On	O
original	O
10BASE5	O
(	O
Thick	O
)	O
Ethernet	O
,	O
the	O
MAU	B-Protocol
was	O
typically	O
clamped	B-Protocol
to	I-Protocol
the	I-Protocol
Ethernet	I-Protocol
cable	I-Protocol
.	O
</s>
<s>
With	O
later	O
standards	O
it	O
was	O
generally	O
integrated	O
into	O
the	O
network	B-Protocol
interface	I-Protocol
controller	I-Protocol
and	O
eventually	O
the	O
entire	O
Ethernet	O
controller	O
was	O
often	O
integrated	O
into	O
a	O
single	O
integrated	O
circuit	O
(	O
"	O
chip	O
"	O
)	O
to	O
reduce	O
cost	O
.	O
</s>
<s>
In	O
most	O
modern	O
switched	O
or	O
hubbed	O
Ethernet	B-Protocol
over	I-Protocol
twisted	I-Protocol
pair	I-Protocol
systems	O
,	O
neither	O
the	O
MAU	B-Protocol
nor	O
the	O
AUI	B-Protocol
interfaces	I-Protocol
exist	O
(	O
apart	O
,	O
perhaps	O
as	O
notional	O
entities	O
for	O
the	O
purposes	O
of	O
thinking	O
about	O
layering	O
the	O
interface	O
)	O
,	O
and	O
the	O
category	B-Protocol
5	I-Protocol
(	O
CAT5	O
)	O
cable	O
connects	O
directly	O
into	O
an	O
Ethernet	O
socket	O
on	O
the	O
host	O
or	O
router	O
.	O
</s>
<s>
For	O
backwards	O
compatibility	O
with	O
equipment	O
which	O
still	O
has	O
external	O
AUI	B-Protocol
interfaces	I-Protocol
,	O
MAUs	B-Protocol
are	O
still	O
available	O
with	O
10BASE2	O
or	O
10BASE-T	B-Protocol
connections	O
.	O
</s>
<s>
The	O
following	O
standard	O
,	O
Fast	B-Protocol
Ethernet	I-Protocol
introduces	O
division	O
onto	O
Media	B-Protocol
Access	I-Protocol
Controller	I-Protocol
(	O
MAC	O
)	O
and	O
Physical	O
Layer	O
Interface	O
(	O
PHY	O
)	O
layers	O
connected	O
with	O
Media	B-Protocol
Independent	I-Protocol
Interface	I-Protocol
(	O
MII	O
)	O
.	O
</s>
<s>
Some	O
early	O
Fast	B-Protocol
Ethernet	I-Protocol
hardware	O
had	O
a	O
physical	O
external	O
MII	O
connectors	O
,	O
functionally	O
similar	O
to	O
AUI	B-Protocol
connector	O
.	O
</s>
<s>
However	O
,	O
the	O
tradition	O
of	O
using	O
a	O
separate	O
low-level	O
I/O	O
device	O
in	O
networking	O
has	O
continued	O
in	O
fast	O
optical	B-Architecture
fiber	I-Architecture
network	O
interfaces	O
,	O
where	O
the	O
GBIC	B-Protocol
,	O
XENPAK	B-Protocol
,	O
XFP	B-Protocol
,	O
and	O
enhanced	B-Protocol
small	I-Protocol
form-factor	I-Protocol
pluggable	I-Protocol
(	O
SFP+	B-Protocol
)	O
pluggable	O
transceiver	O
modules	O
using	O
the	O
XAUI	B-Protocol
interface	O
play	O
a	O
similar	O
role	O
.	O
</s>
<s>
Objectives	O
of	O
MAU	B-Protocol
:	O
</s>
<s>
MAU	B-Protocol
Characteristics	O
:	O
</s>
<s>
Enables	O
coupling	O
the	O
Physical	O
Layer	O
Signalling	O
(	O
PLS	O
)	O
by	O
way	O
of	O
the	O
AUI	B-Protocol
to	O
the	O
explicit	O
baseband	O
coaxial	O
transmission	O
system	O
.	O
</s>
<s>
Permits	O
the	O
DTE	O
to	O
test	O
the	O
MAU	B-Protocol
and	O
the	O
medium	O
itself	O
.	O
</s>
<s>
Services	O
provided	O
by	O
MAU	B-Protocol
:	O
</s>
<s>
Collision	O
detection	O
and	O
Loop-back	O
functions	O
direct	O
transfer	O
through	O
the	O
MAU	B-Protocol
.	O
</s>
<s>
It	O
removes	O
equipment	O
from	O
the	O
network	O
whenever	O
it	O
continuously	O
transmits	O
for	O
periods	O
significantly	O
longer	O
than	O
required	O
for	O
a	O
maximum-length	O
packet	O
,	O
indicating	O
a	O
possible	O
problem	O
with	O
the	O
NIC	B-Protocol
.	O
</s>
<s>
The	O
MAU	B-Protocol
functions	O
as	O
a	O
direct	O
connection	O
between	O
the	O
baseband	O
medium	O
and	O
the	O
DTE	O
.	O
</s>
<s>
The	O
MAU	B-Protocol
functions	O
as	O
a	O
receive-only	O
connection	O
between	O
the	O
baseband	O
medium	O
and	O
the	O
DTE	O
.	O
</s>
<s>
MAU	B-Protocol
functional	O
specifications	O
:	O
</s>
<s>
It	O
removes	O
equipment	O
from	O
the	O
network	O
whenever	O
it	O
continuously	O
transmits	O
for	O
periods	O
significantly	O
longer	O
than	O
required	O
for	O
a	O
maximum-length	O
packet	O
,	O
indicating	O
a	O
possible	O
problem	O
with	O
the	O
NIC	B-Protocol
.	O
</s>
<s>
MAU	B-Protocol
in	O
this	O
context	O
is	O
not	O
to	O
be	O
confused	O
with	O
a	O
Media	B-Device
Access	I-Device
Unit	I-Device
,	O
which	O
shares	O
the	O
same	O
acronym	O
.	O
</s>
