<s>
Network	B-Architecture
emulation	I-Architecture
is	O
a	O
technique	O
for	O
testing	O
the	O
performance	O
of	O
real	O
applications	O
over	O
a	O
virtual	O
network	O
.	O
</s>
<s>
Network	B-Architecture
emulation	I-Architecture
is	O
the	O
act	O
of	O
testing	O
the	O
behavior	O
of	O
a	O
network	O
(	O
5G	O
,	O
wireless	B-General_Concept
,	O
MANETs	O
,	O
etc	O
)	O
in	O
a	O
lab	O
.	O
</s>
<s>
A	O
personal	B-Device
computer	I-Device
or	O
virtual	B-Architecture
machine	I-Architecture
runs	O
software	B-Application
to	O
perform	O
the	O
network	B-Architecture
emulation	I-Architecture
;	O
a	O
dedicated	B-Application
emulation	I-Application
device	I-Application
is	O
sometimes	O
used	O
for	O
link	O
emulation	B-Application
.	O
</s>
<s>
The	O
primary	O
goal	O
of	O
network	B-Architecture
emulation	I-Architecture
is	O
to	O
create	O
an	O
environment	O
whereby	O
users	O
can	O
connect	O
the	O
devices	O
,	O
applications	O
,	O
products	O
,	O
and/or	O
services	O
being	O
tested	O
to	O
validate	O
their	O
performance	O
,	O
stability	O
,	O
or	O
functionality	O
against	O
real-world	O
network	O
scenarios	O
.	O
</s>
<s>
Emulation	B-Application
differs	O
from	O
simulation	O
in	O
that	O
a	O
network	O
emulator	B-Application
appears	O
to	O
be	O
a	O
network	O
;	O
end-systems	O
such	O
as	O
computers	O
can	O
be	O
attached	O
to	O
the	O
emulator	B-Application
and	O
will	O
behave	O
as	O
if	O
they	O
are	O
attached	O
to	O
a	O
network	O
.	O
</s>
<s>
A	O
network	O
emulator	B-Application
mirrors	O
the	O
network	O
which	O
connects	O
end-systems	O
,	O
not	O
the	O
end-systems	O
themselves	O
.	O
</s>
<s>
Software	B-Application
developers	O
typically	O
want	O
to	O
analyze	O
the	O
response	O
time	O
and	O
sensitivity	O
to	O
packet	O
loss	O
of	O
client-server	O
applications	O
and	O
emulate	O
specific	O
network	O
effects	O
(	O
of	O
5G	O
,	O
Smart	O
homes	O
,	O
industrial	O
IOT	O
,	O
military	O
networks	O
,	O
etc.	O
,	O
)	O
with	O
different	O
round-trip-times	O
,	O
throughputs	O
,	O
bit	O
error	O
rates	O
,	O
and	O
packet	O
drops	O
.	O
</s>
<s>
Two	O
open-source	O
network	O
emulators	B-Application
are	O
Common	O
Open	O
Research	O
Emulator	B-Application
(	O
CORE	O
)	O
and	O
Extendable	O
Mobile	O
Ad	O
hoc	O
Network	O
Emulator	B-Application
(	O
EMANE	O
)	O
.	O
</s>
<s>
external	O
machines/devices	O
can	O
be	O
hooked	O
up	O
to	O
the	O
emulated	B-Application
network	O
with	O
no	O
knowledge	O
of	O
emulation	B-Application
.	O
</s>
<s>
They	O
also	O
support	O
both	O
wired	O
and	O
wireless	B-General_Concept
network	I-General_Concept
emulation	B-Application
with	O
various	O
degrees	O
of	O
fidelity	O
.	O
</s>
<s>
A	O
CORE	O
is	O
more	O
useful	O
for	O
quick	O
network	O
layouts	O
(	O
layer	O
3	O
and	O
above	O
)	O
and	O
single-machine	O
emulation	B-Application
.	O
</s>
<s>
EMANE	O
is	O
better	O
suited	O
for	O
distributed	O
high-fidelity	O
large-scale	O
network	B-Architecture
emulation	I-Architecture
(	O
layers	O
1/2	O
)	O
.	O
</s>
<s>
The	O
most	O
popular	O
network	O
simulation	O
software	B-Application
packages	O
,	O
OPNET	O
and	O
Tetcos	O
NetSim	O
,	O
also	O
have	O
emulation	B-Application
modules	O
for	O
real-time	O
device	O
connectivity	O
.	O
</s>
<s>
In	O
general	O
simulation	O
tools	O
with	O
emulation	B-Application
capabilities	O
provide	O
more	O
sophistication	O
than	O
emulation	B-Application
devices	O
.	O
</s>
<s>
Emulation	B-Application
devices	O
only	O
provide	O
for	O
emulation	B-Application
of	O
the	O
physical	O
link	O
and	O
do	O
not	O
factor	O
in	O
the	O
effects	O
of	O
the	O
higher	O
layers	O
(	O
MAC	O
,	O
network	O
,	O
transport	O
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
Simulation	O
tools	O
however	O
model	O
effects	O
from	O
different	O
layers	O
of	O
the	O
network	O
stack	O
when	O
running	O
in	O
emulation	B-Application
mode	O
.	O
</s>
<s>
The	O
network	O
performance	O
under	O
maximum	O
throughput	O
conditions	O
can	O
be	O
analyzed	O
by	O
network	B-Protocol
traffic	I-Protocol
measurement	I-Protocol
in	O
a	O
testbed	O
network	O
,	O
using	O
a	O
network	O
traffic	O
generator	O
such	O
as	O
iperf	B-Language
.	O
</s>
<s>
The	O
traffic	O
generator	O
sends	O
dummy	O
packets	O
,	O
often	O
with	O
a	O
unique	O
packet	O
identifier	O
,	O
making	O
it	O
possible	O
to	O
keep	O
track	O
of	O
the	O
packet	O
delivery	O
in	O
the	O
network	O
using	O
a	O
network	B-Protocol
analyzer	I-Protocol
.	O
</s>
