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Private Networks 163
Figure 5-7
Secondary Subnets
NOTE
Use secondary addressing only as a last resort. Secondary addressing increases network
overhead, degrades throughput, and consumes router resources. When other options are
exhausted, use secondary addressing as a temporary solution.
Private Networks
Users who do not want to use the public network may use private addresses. The RFC has
defined a set of addresses that will never be assigned public. Any user can use these addresses
privately. No user may use these addresses publicly.
NOTE
Use the 10.0.0.0 network as a private address. You'll never outgrow it!
Table 5-9 displays the private addresses that will never be routed onto the Internet.
Table 5-9
Private Addresses
Address
Class
10.0.0.0
A
172.16.0.0/16­172.31.0.0/16
B
192.168.0.0/24­192.168.255.0/24
C
Router B
E2
Router B
E1
Router A
Subnet 131.108.1.0
Route D
Subnet 131.108.2.0
87200333.book Page 163 Wednesday, August 22, 2001 2:37 PM