NETGEAR CG814WG manual MAC Addresses and Address Resolution Protocol

Hardware Manual for the Model CG814WG Wireless Cable Modem Gateway

192.168.0.2

192.168.0.3

192.168.0.4

192.168.0.5

Private IP addresses assigned by user

IP addresses assigned by ISP

192.168.0.1172.21.15.105

Internet

Figure D-3: Single IP Address Operation Using NAT

This scheme offers the additional benefit of firewall-like protection because the internal LAN addresses are not available to the Internet through the translated connection. All incoming inquiries are filtered out by the router. This filtering can prevent intruders from probing your system. However, using port forwarding, you can allow one PC (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. To send data between LAN devices, you must convert the IP address of the destination device to its media access control (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.

D-8 Networks, Routing, and Firewall Basics