<s>
The	O
physical	B-Protocol
coding	I-Protocol
sublayer	I-Protocol
(	O
PCS	O
)	O
is	O
a	O
networking	O
protocol	O
sublayer	O
in	O
the	O
Fast	B-Protocol
Ethernet	I-Protocol
,	O
Gigabit	O
Ethernet	O
,	O
and	O
10	O
Gigabit	O
Ethernet	O
standards	O
.	O
</s>
<s>
It	O
resides	O
at	O
the	O
top	O
of	O
the	O
physical	B-Application
layer	I-Application
(	O
PHY	O
)	O
,	O
and	O
provides	O
an	O
interface	O
between	O
the	O
Physical	B-Protocol
Medium	I-Protocol
Attachment	I-Protocol
(	O
PMA	O
)	O
sublayer	O
and	O
the	O
media-independent	B-Protocol
interface	I-Protocol
(	O
MII	O
)	O
.	O
</s>
<s>
The	O
Ethernet	O
PCS	O
sublayer	O
is	O
at	O
the	O
top	O
of	O
the	O
Ethernet	O
physical	B-Application
layer	I-Application
(	O
PHY	O
)	O
.	O
</s>
<s>
Classic	O
Ethernet	O
uses	O
Manchester	B-Protocol
code	I-Protocol
in	O
the	O
Physical	O
signaling	O
sublayer	O
(	O
PLS	O
)	O
,	O
encoding	O
each	O
bit	O
as	O
a	O
high-low	O
(	O
logical	O
zero	O
)	O
or	O
low-high	O
transition	O
(	O
logical	O
one	O
)	O
.	O
</s>
<s>
100BASE-X	B-Protocol
for	O
fiber	O
(	O
100BASE-FX	O
)	O
and	O
twisted	O
pair	O
copper	O
(	O
100BASE-TX	B-Protocol
)	O
encodes	O
data	O
nibbles	O
to	O
five-bit	O
code	O
groups	O
(	O
4B5B	B-Protocol
)	O
.	O
</s>
<s>
1000BASE-X	O
for	O
fiber	O
and	O
150Ω	O
balanced	O
copper	O
(	O
twinaxial	O
)	O
uses	O
8b/10b	B-Protocol
encoding	I-Protocol
with	O
a	O
symbol	O
rate	O
of	O
1.25	O
GBd	O
.	O
</s>
<s>
1000BASE-T	O
for	O
twisted	O
pair	O
copper	O
splits	O
the	O
data	O
into	O
four	O
lanes	O
and	O
uses	O
four-dimensional	O
,	O
five-level	O
(	O
quinary	O
)	O
Trellis	O
modulation	O
with	O
PAM-5	B-Device
and	O
a	O
symbol	O
rate	O
of	O
125	O
MBd	O
.	O
</s>
<s>
This	O
rate	O
does	O
not	O
match	O
the	O
rate	O
9.953	O
Gbit/s	O
used	O
in	O
SONET	B-Protocol
and	O
SDH	O
and	O
is	O
not	O
supported	O
over	O
a	O
WAN	O
based	O
on	O
SONET	B-Protocol
or	O
SDH	O
.	O
</s>
<s>
10GBASE-X	O
(	O
LAN/WAN	O
)	O
uses	O
8b/10b	B-Protocol
encoding	I-Protocol
over	O
four	O
lanes	O
at	O
3.125	O
GBd	O
each	O
and	O
is	O
used	O
for	O
10GBASE-LX4	O
(	O
single-mode	O
and	O
multi-mode	O
fiber	O
)	O
,	O
10GBASE-CX4	O
(	O
twinax	O
)	O
,	O
and	O
10GBASE-KX4	O
(	O
backplane	O
)	O
.	O
</s>
<s>
It	O
uses	O
64/66b	O
encoding	O
and	O
lowers	O
the	O
MAC	O
rate	O
to	O
9.95Gbit/s	O
,	O
so	O
that	O
is	O
compatible	O
with	O
SONET	B-Protocol
STS-192c	O
data	O
rates	O
and	O
SDH	O
VC-4-64	O
transmission	O
standards	O
when	O
wrapped	O
into	O
a	O
SONET	B-Protocol
frame	O
.	O
</s>
<s>
These	O
lanes	O
–	O
four	O
for	O
40	O
Gbit/s	O
,	O
four	O
or	O
ten	O
for	O
100	O
Gbit/s	O
per	O
direction	O
–	O
are	O
either	O
transmitted	O
separately	O
over	O
short	O
distance	O
or	O
together	O
with	O
coarse	B-Architecture
wavelength	I-Architecture
division	I-Architecture
multiplexing	I-Architecture
on	O
long	O
distance	O
fiber	O
(	O
-LR	O
)	O
.	O
</s>
