<s>
A	O
network	B-Protocol
virtualization	I-Protocol
platform	I-Protocol
decouples	O
the	O
hardware	O
plane	O
from	O
the	O
software	O
plane	O
such	O
that	O
the	O
host	O
hardware	O
plane	O
can	O
be	O
administratively	O
programmed	O
to	O
assign	O
its	O
resources	O
to	O
the	O
software	O
plane	O
.	O
</s>
<s>
This	O
allows	O
for	O
the	O
virtualization	B-General_Concept
of	O
CPU	O
,	O
memory	O
,	O
disk	O
and	O
most	O
importantly	O
network	O
IO	O
.	O
</s>
<s>
Upon	O
such	O
virtualization	B-General_Concept
of	O
hardware	O
resources	O
,	O
the	O
platform	O
can	O
accommodate	O
multiple	O
virtual	O
network	O
applications	O
such	O
as	O
firewalls	B-Application
,	O
routers	B-Protocol
,	O
Web	O
filters	O
,	O
and	O
intrusion	O
prevention	O
systems	O
,	O
all	O
functioning	O
much	O
like	O
standalone	O
hardware	O
appliances	O
,	O
but	O
contained	O
within	O
a	O
single	O
hardware	O
appliance	O
.	O
</s>
<s>
Server	O
virtualization	B-General_Concept
,	O
a	O
technology	O
that	O
has	O
become	O
mainstream	O
,	O
originally	O
gained	O
popularity	O
when	O
VMware	O
entered	O
the	O
market	O
in	O
2001	O
with	O
its	O
GSX	O
server	O
software	O
.	O
</s>
<s>
One	O
of	O
the	O
problems	O
with	O
server	O
virtualization	B-General_Concept
is	O
in	O
how	O
applications	O
are	O
networked	O
together	O
.	O
</s>
<s>
Within	O
a	O
server	O
virtualization	B-General_Concept
environment	O
,	O
applications	O
are	O
interconnected	O
by	O
what	O
is	O
referred	O
to	O
as	O
a	O
virtual	O
switch	O
,	O
which	O
is	O
very	O
different	O
from	O
high-performing	O
hardware-based	O
network	O
switches	O
offered	O
by	O
the	O
likes	O
of	O
Juniper	O
Networks	O
and	O
Cisco	O
Systems	O
.	O
</s>
<s>
Because	O
of	O
this	O
software	O
approach	O
to	O
switching	O
,	O
networking	O
applications	O
such	O
as	O
firewalls	B-Application
and	O
routers	B-Protocol
,	O
which	O
require	O
high	O
levels	O
of	O
throughput	O
and	O
low	O
levels	O
of	O
latency	O
,	O
were	O
not	O
ideal	O
to	O
operate	O
within	O
a	O
server	O
virtualized	B-General_Concept
environment	O
,	O
while	O
applications	O
less	O
sensitive	O
to	O
throughput	O
and	O
latency	O
such	O
as	O
email	O
and	O
file	O
sharing	O
were	O
ideal	O
.	O
</s>
<s>
Initially	O
,	O
network	O
virtualization	B-General_Concept
only	O
involved	O
the	O
separation	O
of	O
the	O
control	O
plane	O
and	O
the	O
forwarding	O
plane	O
(	O
management	O
and	O
packet	O
transmission	O
)	O
within	O
networking	O
devices	O
like	O
switches	O
.	O
</s>
<s>
This	O
has	O
shifted	O
to	O
include	O
the	O
totality	O
of	O
virtualizing	B-General_Concept
a	O
network	O
,	O
including	O
how	O
the	O
network	O
is	O
programmed	O
,	O
administered	O
,	O
and	O
deployed	O
,	O
be	O
it	O
hardware	O
,	O
software	O
,	O
or	O
management	O
and	O
packet	O
transmission	O
.	O
</s>
