Single Ip Address Operation Using Nat - NETGEAR CG814WG Reference Manual

Reference Manual for the Model CG814WG Wireless Cable Modem Gateway
Regardless of your particular situation, do not create an arbitrary IP address; always follow the
guidelines explained here. For more information about address assignment, refer to RFC 1597,
Address Allocation for Private Internets, and RFC 1466, Guidelines for Management of IP
Address Space. The Internet Engineering Task Force (IETF) publishes RFCs on its Web site at
www.ietf.org.

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
CG814WG 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
192.168.0.4
192.168.0.5
Figure B-3: Single IP Address Operation Using NAT
B-8
Private IP addresses
assigned by user
192.168.0.1
IP addresses
assigned by ISP
172.21.15.105
Internet
Networks, Routing, and Firewall Basics
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