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Chapter 2: Planning your Network
The Gateway’s Functions
ADSL Gateway with 4-Port Switch
Chapter 2: Planning your Network
The Gateway’s Functions
A Gateway is a network device that connects two networks together.
In this instance, the Gateway connects your Local Area Network (LAN), or the group of computers in your home or
office, to the Internet. The Gateway processes and regulates the data that travels between these two networks.
The Gateway’s NAT feature protects your network of computers so users on the public, Internet side cannot
“see” your computers. This is how your network remains private. The Gateway protects your network by
inspecting every packet coming in through the Internet port before delivery to the appropriate computer on your
network. The Gateway inspects Internet port services like the web server, ftp server, or other Internet
applications, and, if allowed, it will forward the packet to the appropriate computer on the LAN side.
Remember that the Gateway’s ports connect to two sides. The LAN ports connect to the LAN, and the ADSL port
connects to the Internet. The LAN ports transmit data at 10/100Mbps.
IP Addresses
What’s an IP Address?
IP stands for Internet Protocol. Every device on an IP-based network, including computers, print servers, and
Gateways, requires an IP address to identify its “location,” or address, on the network. This applies to both the
Internet and LAN connections. There are two ways of assigning an IP address to your network devices. You can
assign static IP addresses or use the Gateway to assign IP addresses dynamically.
Static IP Addresses
A static IP address is a fixed IP address that you assign manually to a computer or other device on the network.
Since a static IP address remains valid until you disable it, static IP addressing ensures that the device assigned
it will always have that same IP address until you change it. Static IP addresses must be unique and are
commonly used with network devices such as server computers or print servers.
LAN: the computers and networking products that
make up your local network
NOTE: Since the Gateway is a device that connects two
networks, it needs two IP addresses—one for the LAN,
and one for the Internet. In this User Guide, you’ll see
references to the “Internet IP address” and the “LAN IP
address.”
Since the Gateway uses NAT technology, the only IP
address that can be seen from the Internet for your
network is the Gateway’s Internet IP address. However,
even this Internet IP address can be blocked, so that the
Gateway and network seem invisible to the Internet—
see the Block WAN Requests description under Security
in “Chapter 5: Configuring the ADSL Gateway.”
Figure 2-1: A Network with the Gateway
FTP: a protocol used to transfer files over a TCP/IP network