<s>
IP	B-Protocol
load	I-Protocol
testers	I-Protocol
are	O
a	O
class	O
of	O
protocol	B-Protocol
analyzers	I-Protocol
focused	O
on	O
the	O
practical	O
evaluation	O
of	O
router	B-Protocol
performance	O
.	O
</s>
<s>
Router	B-Protocol
performance	O
is	O
usually	O
broken	O
down	O
into	O
two	O
categories	O
:	O
forwarding	B-Protocol
performance	I-Protocol
(	O
or	O
data	B-Protocol
plane	I-Protocol
)	O
,	O
and	O
routing	B-Protocol
performance	I-Protocol
(	O
or	O
control	O
plane	O
)	O
.	O
</s>
<s>
To	O
test	O
forwarding	B-Protocol
performance	I-Protocol
,	O
IP	B-Protocol
load	I-Protocol
testers	I-Protocol
typically	O
surround	O
a	O
router	B-Protocol
with	O
simulated	O
Internet	O
traffic	O
.	O
</s>
<s>
The	O
first	O
method	O
approximates	O
real	O
Internet	O
traffic	O
by	O
using	O
a	O
representative	O
mix	O
of	O
packet	O
lengths	O
,	O
usually	O
referred	O
to	O
as	O
IMIX	B-Protocol
.	O
</s>
<s>
Another	O
popular	O
technique	O
is	O
to	O
blast	O
the	O
router	B-Protocol
with	O
the	O
shortest	O
packet	O
lengths	O
possible	O
,	O
in	O
order	O
to	O
stress	O
the	O
computational	O
performance	O
of	O
the	O
router	B-Protocol
.	O
</s>
<s>
In	O
both	O
cases	O
,	O
the	O
IP	B-Protocol
load	I-Protocol
tester	I-Protocol
measures	O
the	O
performance	O
of	O
the	O
router	B-Protocol
in	O
terms	O
of	O
loss	B-Protocol
,	O
latency	O
and	O
throughput	O
.	O
</s>
<s>
To	O
test	O
the	O
control	O
plane	O
,	O
IP	B-Protocol
load	I-Protocol
testers	I-Protocol
typically	O
emulate	O
various	O
protocols	O
via	O
the	O
test	O
ports	O
in	O
order	O
to	O
connect	O
to	O
the	O
real	O
implementations	O
of	O
those	O
protocols	O
on	O
the	O
router	B-Protocol
itself	O
.	O
</s>
<s>
For	O
example	O
,	O
within	O
the	O
core	O
of	O
the	O
Internet	O
,	O
various	O
routing	B-Protocol
protocols	I-Protocol
are	O
used	O
for	O
the	O
control	O
plane	O
,	O
or	O
routing	O
function	O
of	O
routers	B-Protocol
.	O
</s>
<s>
Core	O
routing	B-Protocol
protocols	I-Protocol
include	O
BGP	B-Protocol
,	O
IS-IS	B-Protocol
,	O
OSPF	B-Protocol
,	O
and	O
RIP	B-Protocol
.	O
</s>
<s>
Control	O
plane	O
performance	O
is	O
usually	O
characterized	O
by	O
measurements	O
of	O
scalability	B-Architecture
and	O
performance	O
.	O
</s>
<s>
Scalability	B-Architecture
typically	O
means	O
how	O
many	O
protocol	O
sessions	B-Protocol
can	O
be	O
handled	O
by	O
the	O
router	B-Protocol
at	O
one	O
time	O
,	O
and	O
ultimately	O
is	O
a	O
stress	O
of	O
memory	O
.	O
</s>
<s>
Performance	O
usually	O
refers	O
to	O
a	O
time-varying	O
parameter	O
,	O
such	O
as	O
sessions	B-Protocol
per	O
second	O
,	O
and	O
ultimately	O
is	O
a	O
stress	O
of	O
CPU	O
power	O
.	O
</s>
