<s>
A	O
data	B-Device
monitoring	I-Device
switch	I-Device
is	O
a	O
networking	O
hardware	O
appliance	O
that	O
provides	O
a	O
pool	O
of	O
monitoring	O
tools	O
with	O
access	O
to	O
traffic	O
from	O
a	O
large	O
number	O
of	O
network	O
links	O
.	O
</s>
<s>
Data	B-Device
monitoring	I-Device
switches	I-Device
enable	O
organizations	O
to	O
use	O
their	O
monitoring	O
tools	O
more	O
efficiently	O
,	O
centralize	O
traffic	O
monitoring	O
functions	O
,	O
and	O
share	O
tools	O
and	O
traffic	O
access	O
between	O
groups	O
.	O
</s>
<s>
Several	O
other	O
terms	O
have	O
been	O
used	O
to	O
describe	O
this	O
class	O
of	O
devices	O
,	O
including	O
data	B-Device
access	I-Device
switch	I-Device
,	O
tool	B-Device
aggregator	I-Device
,	O
network	B-Device
packet	I-Device
broker	I-Device
,	O
net	B-Device
tool	I-Device
optimizer	I-Device
,	O
and	O
distributed	B-Device
filter	I-Device
tap	I-Device
.	O
</s>
<s>
A	O
data	B-Device
monitoring	I-Device
switch	I-Device
typically	O
provides	O
24	O
to	O
38	O
ports	O
in	O
a	O
1U	O
19-inch	O
chassis	O
,	O
with	O
higher	O
port	O
density	O
devices	O
expected	O
in	O
the	O
future	O
(	O
ask	O
about	O
dimensions	O
from	O
the	O
vendor	O
-	O
devices	O
with	O
higher	O
port	O
density	O
or	O
many	O
card	O
slots	O
may	O
be	O
2U	O
or	O
larger	O
)	O
.	O
</s>
<s>
Network	O
input	O
ports	O
may	O
be	O
paired	O
to	O
provide	O
in-line	O
connectivity	O
(	O
integrated	O
Tap	B-Device
function	O
)	O
,	O
or	O
out	O
of	O
band	O
(	O
mirrored	O
)	O
to	O
take	O
input	O
from	O
external	O
network	B-Device
Taps	I-Device
or	O
network	O
switch	O
SPAN	B-Protocol
ports	I-Protocol
.	O
</s>
<s>
When	O
several	O
monitoring	O
tools	O
are	O
connected	O
to	O
the	O
data	B-Device
monitoring	I-Device
switch	I-Device
's	O
tool	O
ports	O
,	O
copies	O
of	O
traffic	O
from	O
any	O
of	O
the	O
network	O
ports	O
can	O
be	O
switched	O
to	O
any	O
of	O
the	O
tools	O
using	O
the	O
data	B-Device
monitoring	I-Device
switch	I-Device
's	O
management	O
interface	O
.	O
</s>
<s>
A	O
unique	O
characteristic	O
of	O
the	O
data	B-Device
monitoring	I-Device
switch	I-Device
,	O
as	O
opposed	O
to	O
matrix	O
switches	O
and	O
aggregating	O
Taps	O
,	O
is	O
that	O
it	O
can	O
support	O
a	O
flexible	O
set	O
of	O
port	O
mappings	O
including	O
:	O
</s>
<s>
In	O
addition	O
to	O
directing	O
monitoring	O
traffic	O
,	O
data	B-Device
monitoring	I-Device
switches	I-Device
are	O
capable	O
of	O
filtering	O
traffic	O
by	O
Layer	O
2	O
to	O
Layer	O
4	O
protocol	O
criteria	O
such	O
as	O
VLAN	O
or	O
IP	O
address	O
,	O
enabling	O
only	O
traffic	O
of	O
interest	O
to	O
be	O
sent	O
to	O
specific	O
tools	O
.	O
</s>
<s>
Some	O
data	B-Device
monitoring	I-Device
switches	I-Device
offer	O
different	O
management	O
interfaces	O
(	O
fully	O
integrated	O
GUI	O
,	O
automation	O
,	O
etc	O
.	O
</s>
<s>
Data	B-Device
monitoring	I-Device
switches	I-Device
support	O
either	O
or	O
both	O
of	O
the	O
following	O
internal	O
management	O
interfaces	O
:	O
</s>
<s>
A	O
text-based	O
command-line	B-Application
interface	I-Application
(	O
CLI	O
)	O
accessed	O
with	O
a	O
terminal	O
emulation	O
program	O
either	O
locally	O
over	O
a	O
serial	O
port	O
or	O
remotely	O
over	O
a	O
secure	O
(	O
e.g.	O
,	O
SSH	O
)	O
network	O
connection	O
;	O
this	O
interface	O
is	O
sometimes	O
preferred	O
by	O
network	O
administrators	O
,	O
although	O
many	O
data	O
center	O
professionals	O
complain	O
that	O
CLI	O
is	O
too	O
complex	O
.	O
</s>
<s>
Data	B-Device
monitoring	I-Device
switches	I-Device
facilitate	O
centralizing	O
network	O
traffic	O
monitoring	O
in	O
the	O
NOC	O
.	O
</s>
<s>
They	O
can	O
Tap	B-Device
network	O
links	O
directly	O
,	O
instead	O
of	O
relying	O
on	O
switch	O
SPAN	B-Protocol
ports	I-Protocol
for	O
monitoring	O
access	O
.	O
</s>
<s>
This	O
is	O
compared	O
to	O
SPAN	B-Protocol
ports	I-Protocol
,	O
where	O
network	O
traffic	O
can	O
be	O
disrupted	O
if	O
the	O
switch	O
is	O
not	O
properly	O
configured	O
while	O
setting	O
up	O
the	O
SPAN	B-Protocol
port	I-Protocol
.	O
</s>
<s>
Data	B-Device
monitoring	I-Device
switches	I-Device
take	O
a	O
simple	O
concept	O
,	O
the	O
passive	O
network	B-Device
Tap	I-Device
,	O
and	O
make	O
it	O
an	O
expensive	O
,	O
complex	O
device	O
that	O
requires	O
configuration	O
and	O
management	O
.	O
</s>
<s>
Command-Line	B-Application
interfaces	I-Application
are	O
often	O
required	O
for	O
the	O
vast	O
majority	O
of	O
the	O
functions	O
,	O
even	O
on	O
many	O
boxes	O
that	O
also	O
offer	O
a	O
GUI	O
.	O
</s>
