TRENDnet TW-H6W1IR manual Global IP Addresses

TW-H6W1IR ISDN Remote 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 on page 78.

Global IP Addresses	Local IP Addresses
(for use with NAT)	(assigned to computers
	on the local network)
200.100.50.1	192.168.100.2
200.100.50.2	192.168.100.3
200.100.50.3	192.168.100.4
200.100.50.4	192.168.100.5
200.100.50.5	192.168.100.6
	192.168.100.7
	192.168.100.8
	192.168.100.9
	192.168.100.10

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 192.168.100.2) 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.

Configuration and Management 81