Netopia R2121, User Reference Manual

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Understanding IP Addressing C-11
Nested IP subnets
Under cer tain situations, you may wish to create remote subnets from the limited number of IP addresses
issued by your ISP or other authority. You can do this using connection profiles. These subnets can be nested
within the range of IP addresses available to your network.
For example, suppose that you obtain the Class C network address a.b.c.0 to be distributed among three
networks. This network address can be used on your main network while por tions of it can be subnetted to the
two remaining networks.
Note: The IP address a.b.c.0 has letters in place of the first three numbers to generalize it for this example.
The figure at left shows a possible network configuration following this scheme. The main network is set up with
the Class C address a.b.c.0, and contains Router A (which could be a Netopia R2121), a Netopia R2121, and a
number of other hosts. Router A maintains a link to the Internet, and may be used as the default gateway.
Internet
Router A
Router C Router B
a.b.c.0
a.b.c.16
a.b.c.1
a.b.c.2
a.b.c.248
a.b.c.249
a.b.c.128
a.b.c.129