Netopia Router PN Series - Manual (Page 251)

Understanding IP Addressing B-15
The Netopia Router compares the packet’s destination IP address
with the routes in its IP routing table. It begins with the route at the
bottom of the list and works up until there’s a match or the route to
the default gateway is reached.
When a.b.c.249 is masked by the first route’s subnet mask, it
yields a.b.c.248, which matches the network address in the route.
The Netopia Router uses the connection profile associated with the
route to connect to Router C, and then forwards the packet. Router
C delivers the packet to the host on its local network.
The following diagram illustrates the IP address space taken up by
the two remote IP subnets. You can see from the diagram why the
term nested is appropriate for describing these subnets.
1
254
Address range
available to
a.b.c.0, less
the two nested
subnets
248
addresses used
by a.b.c.248
192
128
addresses used
by a.b.c.128