<s>
The	O
Cisco	B-Device
Catalyst	I-Device
6500	I-Device
is	O
a	O
modular	B-Architecture
chassis	I-Architecture
network	B-Protocol
switch	I-Protocol
manufactured	O
by	O
Cisco	O
Systems	O
from	O
1999	O
to	O
2015	O
,	O
capable	O
of	O
delivering	O
speeds	O
of	O
up	O
to	O
"	O
400	O
million	O
packets	B-Protocol
per	O
second	O
"	O
.	O
</s>
<s>
The	O
supervisor	B-Device
engine	I-Device
provides	O
centralised	O
forwarding	O
information	O
and	O
processing	O
;	O
up	O
to	O
two	O
of	O
these	O
cards	O
can	O
be	O
installed	O
in	O
a	O
chassis	O
to	O
provide	O
active/standby	O
or	O
stateful	O
failover	B-General_Concept
.	O
</s>
<s>
The	O
6500	O
Supervisor	O
comprises	O
a	O
Multilayer	B-Application
Switch	I-Application
Feature	O
Card	O
(	O
MSFC	O
)	O
and	O
a	O
Policy	O
Feature	O
Card	O
(	O
PFC	O
)	O
.	O
</s>
<s>
The	O
MSFC	O
runs	O
all	O
software	O
processes	O
,	O
such	O
as	O
routing	B-Protocol
protocols	I-Protocol
.	O
</s>
<s>
The	O
supervisor	O
has	O
connections	O
to	O
the	O
switching	B-Architecture
fabric	I-Architecture
and	O
classic	O
bus	O
,	O
as	O
well	O
as	O
bootflash	O
for	O
the	O
Cisco	B-Protocol
IOS	I-Protocol
software	O
.	O
</s>
<s>
The	O
6500	O
currently	O
supports	O
three	O
operating	O
systems	O
:	O
CatOS	B-Operating_System
,	O
Native	O
IOS	B-Protocol
,	O
and	O
Modular	O
IOS	B-Protocol
.	O
</s>
<s>
CatOS	B-Operating_System
is	O
supported	O
for	O
layer	O
2	O
(	O
switching	O
)	O
operations	O
only	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
CatOS	B-Operating_System
runs	O
on	O
the	O
Switch	O
Processor	O
(	O
SP	O
)	O
portion	O
of	O
the	O
Supervisor	O
,	O
and	O
IOS	B-Protocol
runs	O
on	O
the	O
Route	O
Processor	O
(	O
RP	O
)	O
,	O
also	O
known	O
as	O
the	O
MSFC	O
.	O
</s>
<s>
CatOS	B-Operating_System
does	O
have	O
some	O
missing	O
functionality	O
,	O
and	O
is	O
generally	O
considered	O
'	O
obsolete	O
 '	O
compared	O
to	O
running	O
a	O
switch	O
in	O
Native	O
Mode	O
.	O
</s>
<s>
Cisco	B-Protocol
IOS	I-Protocol
can	O
be	O
run	O
on	O
both	O
the	O
SP	O
and	O
RP	O
.	O
</s>
<s>
In	O
this	O
instance	O
,	O
the	O
user	O
is	O
unaware	O
of	O
where	O
a	O
command	O
is	O
being	O
executed	O
on	O
the	O
switch	O
,	O
even	O
though	O
technically	O
two	O
IOS	B-Protocol
images	O
are	O
loaded	O
—	O
one	O
on	O
each	O
processor	O
.	O
</s>
<s>
Modular	O
IOS	B-Protocol
is	O
a	O
version	O
of	O
Cisco	B-Protocol
IOS	I-Protocol
that	O
employs	O
a	O
modern	O
UNIX-based	O
kernel	O
to	O
overcome	O
some	O
of	O
the	O
limitations	O
of	O
IOS	B-Protocol
.	O
</s>
<s>
The	O
design	O
is	O
such	O
that	O
an	O
incoming	O
packet	B-Protocol
is	O
first	O
queued	O
on	O
the	O
line	O
card	O
and	O
then	O
placed	O
on	O
to	O
the	O
global	O
data	O
bus	O
(	O
dBus	O
)	O
and	O
is	O
copied	O
to	O
all	O
other	O
line	O
cards	O
,	O
including	O
the	O
supervisor	O
.	O
</s>
<s>
When	O
used	O
in	O
combination	O
with	O
a	O
switch	B-Architecture
fabric	I-Architecture
module	O
,	O
each	O
line	O
card	O
has	O
an	O
8Gbit/s	O
connection	O
to	O
the	O
switch	B-Architecture
fabric	I-Architecture
and	O
additionally	O
a	O
connection	O
to	O
the	O
classic	O
bus	O
.	O
</s>
<s>
In	O
this	O
mode	O
,	O
assuming	O
all	O
line	O
cards	O
have	O
a	O
switch	B-Architecture
fabric	I-Architecture
connection	O
,	O
an	O
ingress	O
packet	B-Protocol
is	O
queued	O
as	O
before	O
and	O
its	O
headers	O
are	O
sent	O
along	O
the	O
dBus	O
to	O
the	O
supervisor	O
.	O
</s>
<s>
The	O
initial	O
egress	O
line	O
card	O
takes	O
this	O
information	O
and	O
forwards	O
the	O
data	O
to	O
the	O
correct	O
line	O
card	O
along	O
with	O
the	O
switch	B-Architecture
fabric	I-Architecture
.	O
</s>
<s>
The	O
receiving	O
line	O
card	O
queues	O
the	O
egress	O
packet	B-Protocol
before	O
sending	O
it	O
from	O
the	O
desired	O
port	O
.	O
</s>
<s>
The	O
number	O
gets	O
double	O
because	O
of	O
the	O
switch	B-Architecture
fabric	I-Architecture
being	O
'	O
full	O
duplex	O
 '	O
.	O
</s>
<s>
These	O
line	O
cards	O
have	O
2x8gb	O
connections	O
to	O
the	O
switch	B-Architecture
fabric	I-Architecture
and	O
no	O
classic	O
bus	O
connection	O
.	O
</s>
<s>
In	O
this	O
instance	O
,	O
an	O
ingress	O
packet	B-Protocol
is	O
queued	O
,	O
but	O
its	O
destination	O
is	O
looked	O
up	O
locally	O
.	O
</s>
<s>
The	O
packet	B-Protocol
is	O
then	O
sent	O
across	O
the	O
switch	B-Architecture
fabric	I-Architecture
and	O
queued	O
in	O
the	O
egress	O
line	O
card	O
before	O
being	O
sent	O
.	O
</s>
<s>
This	O
mode	O
of	O
operation	O
acts	O
identically	O
to	O
CEF256	O
,	O
except	O
with	O
2x20gb	O
connections	O
to	O
the	O
switch	B-Architecture
fabric	I-Architecture
and	O
there	O
is	O
no	O
need	O
for	O
a	O
switch	B-Architecture
fabric	I-Architecture
module	O
(	O
this	O
is	O
now	O
integrated	O
into	O
the	O
supervisor	O
)	O
.	O
</s>
<s>
This	O
was	O
first	O
introduced	O
into	O
the	O
Supervisor	B-Device
Engine	I-Device
720	O
.	O
</s>
<s>
The	O
number	O
is	O
doubled	O
to	O
the	O
switch	B-Architecture
fabric	I-Architecture
being	O
'	O
full	O
duplex	O
 '	O
.	O
</s>
<s>
The	O
reason	O
9	O
slots	O
are	O
used	O
for	O
the	O
calculation	O
instead	O
of	O
8	O
for	O
the	O
cef256	O
is	O
that	O
it	O
no	O
longer	O
needs	O
to	O
waste	O
a	O
slot	O
with	O
the	O
switch	B-Architecture
fabric	I-Architecture
module	O
.	O
</s>
<s>
This	O
mode	O
of	O
operation	O
acts	O
identically	O
to	O
dCEF256	O
,	O
except	O
with	O
2x20gb	O
connections	O
to	O
the	O
switch	B-Architecture
fabric	I-Architecture
.	O
</s>
<s>
The	O
6500	O
is	O
able	O
to	O
deliver	O
high	O
densities	O
of	O
Power	B-Device
over	I-Device
Ethernet	I-Device
across	O
the	O
chassis	O
.	O
</s>
<s>
This	O
allows	O
for	O
greater	O
utilisation	O
of	O
the	O
power	O
supplies	O
and	O
potentially	O
increased	O
PoE	B-Device
densities	O
.	O
</s>
<s>
Power	B-Device
over	I-Device
Ethernet	I-Device
(	O
PoE	B-Device
)	O
devices	O
—	O
The	O
system	O
will	O
power	O
down	O
PoE	B-Device
devices	O
in	O
descending	O
order	O
,	O
starting	O
with	O
the	O
highest	O
numbered	O
port	O
on	O
the	O
module	O
in	O
the	O
highest	O
numbered	O
slot	O
.	O
</s>
<s>
Slots	O
containing	O
supervisor	B-Device
engines	I-Device
or	O
Switch	B-Architecture
Fabric	I-Architecture
Modules	O
are	O
bypassed	O
and	O
are	O
not	O
powered	O
down	O
.	O
</s>
<s>
OIR	O
is	O
a	O
feature	O
of	O
the	O
6500	O
which	O
allows	O
hot	B-Device
swapping	I-Device
of	O
most	O
line	O
cards	O
without	O
first	O
powering	O
down	O
the	O
chassis	O
.	O
</s>
