NETGEAR CG814M manual Single IP Address Operation Using NAT

Reference Manual for the Model CG814M Wireless Cable Modem Gateway

Single IP Address Operation Using NAT

In the past, if multiple PCs on a LAN needed to access the Internet simultaneously, you had to obtain a range of IP addresses from the ISP. This type of Internet account is more costly than a single-address account typically used by a single user with a modem, rather than a router. The CG814M Gateway employs an address-sharing method called Network Address Translation (NAT). This method allows several networked PCs to share an Internet account using only a single IP address, which may be statically or dynamically assigned by your ISP.

The router accomplishes this address sharing by translating the internal LAN IP addresses to a single address that is globally unique on the Internet. The internal LAN IP addresses can be either private addresses or registered addresses. For more information about IP address translation, refer to RFC 1631, The IP Network Address Translator (NAT).

The following figure illustrates a single IP address operation.

192.168.0.2

192.168.0.3

Private IP addresses assigned by user

IP addresses assigned by ISP

192.168.0.1172.21.15.105

Internet

192.168.0.4

192.168.0.5

7786EA

Figure 6-3: Single IP Address Operation Using NAT

B-8 Networks, Routing, and Firewall Basics