Reference Manual for the Model CG814M Wireless Cable ... - netgear
Reference Manual for the Model CG814M Wireless Cable ... - netgear
Reference Manual for the Model CG814M Wireless Cable ... - netgear
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<strong>Reference</strong> <strong>Manual</strong> <strong>for</strong> <strong>the</strong> <strong>Model</strong> <strong>CG814M</strong> <strong>Wireless</strong> <strong>Cable</strong> Modem Gateway<br />
Single IP Address Operation Using NAT<br />
In <strong>the</strong> past, if multiple PCs on a LAN needed to access <strong>the</strong> Internet simultaneously, you had to<br />
obtain a range of IP addresses from <strong>the</strong> ISP. This type of Internet account is more costly than a<br />
single-address account typically used by a single user with a modem, ra<strong>the</strong>r than a router. The<br />
<strong>CG814M</strong> Gateway employs an address-sharing method called Network Address Translation<br />
(NAT). This method allows several networked PCs to share an Internet account using only a single<br />
IP address, which may be statically or dynamically assigned by your ISP.<br />
The router accomplishes this address sharing by translating <strong>the</strong> internal LAN IP addresses to a<br />
single address that is globally unique on <strong>the</strong> Internet. The internal LAN IP addresses can be ei<strong>the</strong>r<br />
private addresses or registered addresses. For more in<strong>for</strong>mation about IP address translation, refer<br />
to RFC 1631, The IP Network Address Translator (NAT).<br />
The following figure illustrates a single IP address operation.<br />
192.168.0.2<br />
192.168.0.3<br />
192.168.0.4<br />
192.168.0.5<br />
Private IP addresses<br />
assigned by user<br />
192.168.0.1 172.21.15.105<br />
IP addresses<br />
assigned by ISP<br />
Internet<br />
Figure 6-3: Single IP Address Operation Using NAT<br />
B-8 Networks, Routing, and Firewall Basics<br />
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