<s>
A	O
supernetwork	B-Protocol
,	O
or	O
supernet	B-Protocol
,	O
is	O
an	O
Internet	B-Protocol
Protocol	I-Protocol
(	O
IP	O
)	O
network	O
that	O
is	O
formed	O
by	O
aggregation	O
of	O
multiple	O
networks	O
(	O
or	O
subnets	B-Protocol
)	O
into	O
a	O
larger	O
network	O
.	O
</s>
<s>
The	O
new	O
routing	O
prefix	O
for	O
the	O
aggregate	O
network	O
represents	O
the	O
constituent	O
networks	O
in	O
a	O
single	O
routing	B-Protocol
table	I-Protocol
entry	O
.	O
</s>
<s>
The	O
process	O
of	O
forming	O
a	O
supernet	B-Protocol
is	O
called	O
supernetting	B-Protocol
,	O
prefix	O
aggregation	O
,	O
route	B-Protocol
aggregation	I-Protocol
,	O
or	O
route	B-Protocol
summarization	I-Protocol
.	O
</s>
<s>
Supernetting	B-Protocol
within	O
the	O
Internet	O
serves	O
as	O
a	O
strategy	O
to	O
avoid	O
fragmentation	O
of	O
the	O
IP	B-Protocol
address	I-Protocol
space	O
by	O
using	O
a	O
hierarchical	O
allocation	O
system	O
that	O
delegates	O
control	O
of	O
segments	O
of	O
address	O
space	O
to	O
regional	O
Internet	O
registries	O
.	O
</s>
<s>
This	O
method	O
facilitates	O
regional	O
route	B-Protocol
aggregation	I-Protocol
.	O
</s>
<s>
The	O
benefits	O
of	O
supernetting	B-Protocol
are	O
efficiencies	O
gained	O
in	O
routers	B-Protocol
in	O
terms	O
of	O
memory	O
storage	O
of	O
route	O
information	O
and	O
processing	O
overhead	O
when	O
matching	O
routes	O
.	O
</s>
<s>
Supernetting	B-Protocol
,	O
however	O
,	O
can	O
introduce	O
interoperability	O
issues	O
and	O
other	O
risks	O
.	O
</s>
<s>
In	O
IP	O
networking	O
terminology	O
,	O
a	O
supernet	B-Protocol
is	O
a	O
block	O
of	O
contiguous	O
subnetworks	B-Protocol
addressed	O
as	O
a	O
single	O
subnet	B-Protocol
from	O
the	O
perspective	O
of	O
the	O
larger	O
network	O
.	O
</s>
<s>
Supernets	B-Protocol
are	O
always	O
larger	O
than	O
their	O
component	O
networks	O
.	O
</s>
<s>
Supernetting	B-Protocol
is	O
the	O
process	O
of	O
aggregating	O
routes	O
to	O
multiple	O
smaller	O
networks	O
,	O
thus	O
saving	O
storage	O
space	O
in	O
the	O
routing	B-Protocol
table	I-Protocol
,	O
simplifying	O
routing	O
decisions	O
and	O
reducing	O
route	O
advertisements	O
to	O
neighboring	O
gateways	O
.	O
</s>
<s>
Supernetting	B-Protocol
has	O
helped	O
address	O
the	O
increasing	O
size	O
of	O
routing	B-Protocol
tables	I-Protocol
as	O
the	O
Internet	O
has	O
expanded	O
.	O
</s>
<s>
Supernetting	B-Protocol
in	O
large	O
,	O
complex	O
networks	O
can	O
isolate	O
topology	O
changes	O
from	O
other	O
routers	B-Protocol
.	O
</s>
<s>
If	O
a	O
router	B-Protocol
only	O
advertises	O
a	O
summary	O
route	O
to	O
the	O
next	O
router	B-Protocol
,	O
then	O
it	O
does	O
not	O
need	O
to	O
advertise	O
any	O
changes	O
to	O
specific	O
subnets	B-Protocol
within	O
the	O
summarized	O
range	O
.	O
</s>
<s>
Hence	O
,	O
it	O
increases	O
the	O
speed	O
of	O
convergence	B-Protocol
resulting	O
in	O
a	O
more	O
stable	O
environment	O
.	O
</s>
<s>
Supernetting	B-Protocol
requires	O
the	O
use	O
of	O
routing	O
protocols	O
that	O
support	O
Classless	B-Protocol
Inter-Domain	I-Protocol
Routing	I-Protocol
(	O
CIDR	B-Protocol
)	O
.	O
</s>
<s>
Interior	B-Protocol
Gateway	I-Protocol
Routing	I-Protocol
Protocol	I-Protocol
,	O
Exterior	B-Protocol
Gateway	I-Protocol
Protocol	I-Protocol
and	O
version	O
1	O
of	O
the	O
Routing	B-Protocol
Information	I-Protocol
Protocol	I-Protocol
(	O
RIPv1	B-Protocol
)	O
assume	O
classful	B-Protocol
addressing	I-Protocol
,	O
and	O
therefore	O
cannot	O
transmit	O
the	O
subnet	B-Protocol
mask	I-Protocol
information	O
required	O
for	O
supernetting	B-Protocol
.	O
</s>
<s>
Enhanced	B-Protocol
Interior	I-Protocol
Gateway	I-Protocol
Routing	I-Protocol
Protocol	I-Protocol
(	O
EIGRP	B-Protocol
)	O
supports	O
CIDR	B-Protocol
.	O
</s>
<s>
By	O
default	O
,	O
EIGRP	B-Protocol
summarizes	O
the	O
routes	O
within	O
the	O
routing	B-Protocol
table	I-Protocol
and	O
forwards	O
these	O
summarized	O
routes	O
to	O
its	O
peers	O
.	O
</s>
<s>
Other	O
routing	O
protocols	O
with	O
CIDR	B-Protocol
support	O
include	O
RIPv2	O
,	O
Open	B-Protocol
Shortest	I-Protocol
Path	I-Protocol
First	I-Protocol
,	O
EIGRP	B-Protocol
,	O
IS-IS	O
and	O
Border	B-Protocol
Gateway	I-Protocol
Protocol	I-Protocol
.	O
</s>
<s>
A	O
company	O
that	O
operates	O
150	O
accounting	O
services	O
in	O
each	O
of	O
50	O
districts	O
has	O
a	O
router	B-Protocol
in	O
each	O
office	O
connected	O
with	O
a	O
Frame	B-Protocol
Relay	I-Protocol
link	O
to	O
its	O
corporate	O
headquarters	O
.	O
</s>
<s>
Without	O
supernetting	B-Protocol
,	O
the	O
routing	B-Protocol
table	I-Protocol
on	O
any	O
given	O
router	B-Protocol
might	O
have	O
to	O
account	O
for	O
150	O
routers	B-Protocol
in	O
each	O
of	O
the	O
50	O
districts	O
,	O
or	O
7500	O
different	O
networks	O
.	O
</s>
<s>
However	O
,	O
if	O
a	O
hierarchical	O
addressing	O
system	O
is	O
implemented	O
with	O
supernetting	B-Protocol
,	O
then	O
each	O
district	O
has	O
a	O
centralized	O
site	O
as	O
an	O
interconnection	O
point	O
.	O
</s>
<s>
Each	O
router	B-Protocol
now	O
only	O
recognizes	O
its	O
own	O
subnet	B-Protocol
and	O
the	O
other	O
49	O
summarized	O
routes	O
.	O
</s>
<s>
The	O
determination	O
of	O
the	O
summary	O
route	O
on	O
a	O
router	B-Protocol
involves	O
the	O
recognition	O
of	O
the	O
number	O
of	O
highest-order	O
bits	O
that	O
match	O
all	O
addresses	O
.	O
</s>
<s>
A	O
router	B-Protocol
has	O
the	O
following	O
networks	O
in	O
its	O
routing	B-Protocol
table	I-Protocol
:	O
</s>
<s>
The	O
subnet	B-Protocol
mask	I-Protocol
is	O
255.255.240.0	O
.	O
</s>
<s>
In	O
another	O
example	O
,	O
an	O
ISP	O
is	O
assigned	O
a	O
block	O
of	O
IP	B-Protocol
addresses	I-Protocol
by	O
a	O
regional	O
Internet	O
registry	O
(	O
RIR	O
)	O
of	O
172.1.0.0	O
to	O
172.1.255.255	O
.	O
</s>
<s>
The	O
ISP	O
might	O
then	O
assign	O
subnetworks	B-Protocol
to	O
each	O
of	O
their	O
downstream	O
clients	O
,	O
e.g.	O
,	O
Customer	O
A	O
will	O
have	O
the	O
range	O
172.1.1.0	O
to	O
172.1.1.255	O
,	O
Customer	O
B	O
would	O
receive	O
the	O
range	O
172.1.2.0	O
to	O
172.1.2.255	O
and	O
Customer	O
C	O
would	O
receive	O
the	O
range	O
172.1.3.0	O
to	O
172.1.3.255	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
Instead	O
of	O
an	O
entry	O
for	O
each	O
of	O
the	O
subnets	B-Protocol
172.1.1.x	O
and	O
172.1.2.x	O
,	O
etc.	O
,	O
the	O
ISP	O
could	O
aggregate	O
the	O
entire	O
172.1.x.x	O
address	O
range	O
and	O
advertise	O
the	O
network	O
172.1.0.0/16	O
,	O
which	O
would	O
reduce	O
the	O
number	O
of	O
entries	O
in	O
the	O
global	O
routing	B-Protocol
table	I-Protocol
.	O
</s>
<s>
The	O
following	O
supernetting	B-Protocol
risks	O
have	O
been	O
identified	O
:	O
</s>
<s>
Adverse	O
impact	O
in	O
heterogeneous	O
routing	O
environments	O
with	O
discontiguous	O
subnets	B-Protocol
.	O
</s>
