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DI-1162 Remote Access Router
NAT is the initial protocol set forth by RFC 1631 and provides a means
in which private networks can communicate with the Internet by using
a small number of IP addresses. In our discussion, we will use the
example IP addresses listed in the table below and the network diagram
shown at the beginning of this section.
Global IP Addresses
(for use with NAT)
200.100.50.1
200.100.50.2
200.100.50.3
200.100.50.4
200.100.50.5
Please note that in the above table there are 9 users on the local
network using 5 global IP addresses to access the Internet.
When a packet on the local network arrives at the router and needs to
be sent to the Internet, NAT will change the source IP address (for
example 192.169.100.2) to a global address (200.100.50.1, for
example). If this packet generates a reply (as for example, a request to
view a web page will), NAT will change the destination IP address on
the reply packet back to the local IP address for delivery to the machine
on the local (stub) network.
The difference between static and dynamic NAT is that once the five
global addresses are assigned when using static NAT, they will never
change. The only way to change them is by using the console program
to manually reassign them. When using dynamic NAT, the router will
map a local IP address to a global IP address whenever a request is
Configuration and Management
Local IP Addresses
(assigned to computers
on the local network)
192.168.100.1
192.168.100.2
192.168.100.3
192.168.100.4
192.168.100.5
192.168.100.6
192.168.100.7
192.168.100.8
192.168.100.9
192.168.100.10
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