Mac Addresses And Address Resolution Protocol; Figure 1-3. Single Ip Address Operation Using Nat - NETGEAR RT338 Reference Manual

Reference Guide for the Model RT338 ISDN Router
Figure 1-3 illustrates a single IP address operation.
192.168.0.2
192.168.0.3
192.168.0.4
192.168.0.5
Figure 1-3. Single IP Address Operation Using NAT
This scheme offers the additional benefit of protection similar to that of a firewall. Internal LAN
addresses are not available to the Internet through the translated connection. All incoming
inquiries are filtered out by the router. Filtering can prevent intruders from probing your system.
You can use the port forwarding feature to allow specific services (for example, a Web server) on
your local network to be accessible to outside users.

MAC Addresses and Address Resolution Protocol

An IP address alone cannot be used to deliver data from one LAN device to another. In order for
data to be sent between LAN devices, you must convert the IP address of the destination device to
its MAC address. Each device on an Ethernet network has a unique MAC address, which is a
48-bit number assigned to each device by the manufacturer. The technique that associates the IP
address with a MAC address is known as address resolution. Internet Protocol uses the Address
Resolution Protocol (ARP) to resolve MAC addresses.
1-12
Private IP addresses
assigned by user
192.168.0.1
IP addresses
assigned by ISP
172.21.15.105
Internet
7786EA
Introduction