<s>
Computer	B-Architecture
networks	I-Architecture
are	O
connected	O
together	O
to	O
form	O
larger	O
networks	O
such	O
as	O
campus	B-General_Concept
networks	I-General_Concept
,	O
corporate	B-General_Concept
networks	I-General_Concept
,	O
or	O
the	O
Internet	O
.	O
</s>
<s>
Routers	B-Protocol
are	O
network	O
devices	O
that	O
may	O
be	O
used	O
to	O
connect	O
these	O
networks	O
(	O
e.g.	O
,	O
a	O
home	O
network	O
connected	O
to	O
the	O
network	O
of	O
an	O
Internet	O
service	O
provider	O
)	O
.	O
</s>
<s>
When	O
a	O
router	B-Protocol
interconnects	O
many	O
networks	O
or	O
handles	O
much	O
network	O
traffic	O
,	O
it	O
may	O
become	O
a	O
bottleneck	O
and	O
cause	O
network	B-Protocol
congestion	I-Protocol
(	O
i.e.	O
,	O
traffic	O
loss	O
)	O
.	O
</s>
<s>
One	O
of	O
them	O
is	O
the	O
network	B-Device
search	I-Device
engine	I-Device
(	O
NSE	O
)	O
,	O
also	O
known	O
as	O
network	B-Device
search	I-Device
element	I-Device
.	O
</s>
<s>
This	O
special-purpose	O
device	O
helps	O
a	O
router	B-Protocol
perform	O
one	O
of	O
its	O
core	O
and	O
repeated	O
functions	O
very	O
fast	O
:	O
address	O
lookup	B-Data_Structure
.	O
</s>
<s>
Besides	O
routing	B-Protocol
,	O
NSE-based	O
address	O
lookup	B-Data_Structure
is	O
also	O
used	O
to	O
keep	O
track	O
of	O
network	O
service	O
usage	O
for	O
billing	O
purposes	O
,	O
or	O
to	O
look	O
up	O
patterns	O
of	O
information	O
in	O
the	O
data	O
passing	O
through	O
the	O
network	O
for	O
security	O
reasons	O
.	O
</s>
<s>
Network	B-Device
search	I-Device
engines	I-Device
are	O
often	O
available	O
as	O
ASIC	O
chips	O
to	O
be	O
interfaced	B-Device
with	O
the	O
network	B-General_Concept
processor	I-General_Concept
of	O
the	O
router	B-Protocol
.	O
</s>
<s>
Content-addressable	B-Data_Structure
memory	I-Data_Structure
and	O
Trie	B-General_Concept
are	O
two	O
techniques	O
commonly	O
used	O
when	O
implementing	O
NSEs	O
.	O
</s>
