Wireless Networking Fundamentals

Transmission Control Protocol/Internet Protocol (TCP/IP) is the most common
protocol for transmitting packets around a network. Every computer on a
TCP/IP network must have its own IP address, which is a 32-bit numeric
address that’s written as four groups of numbers separated by periods
(for example, 192.168.1.100). Each number of these four sets of numbers is
known as an octet, which can have a value from 0 to 255. The Internet transmits
packets by using the TCP/IP protocol. When you use the Internet, the
Internet service provider (ISP) — such as AOL, EarthLink, or your cable or
DSL provider — assigns a unique TCP/IP number to your computer. For the
period that your computer is connected, your computer “leases” this unique
address and uses it like a postal address to send and receive information
over the Internet to and from other computers.
A router with the Network Address Translation (NAT) feature also helps to
protect the data on your computers from intruders. The NAT feature acts as
a protection because it hides the real network addresses of networked computers
from computers outside the network. Many WAN routers also have
additional security features that more actively prevent intruders from gaining
unauthorized access to your network through the Internet. This type of protection
is sometimes described generically as a firewall. Good firewall software
usually offers a suite of tools that not only block unauthorized access
but also help you to detect and monitor suspicious computer activity. In
addition, these tools provide you with ways to safely permit computers on
your network to access the Internet.

Internet gateways

These days, you can get a device that really does it all: a wireless Internet gateway.
These devices combine all the features of an access point, a router, and
a broadband modem (typically, cable or DSL, but this could also be a fiberoptic
connection such as Verizon’s FiOS or even another wireless connection).
Some wireless Internet gateways even include a print server (which
enables you to connect a printer directly to the gateway and use it from any
networked PC), a dial-up modem, and even some Ethernet ports for computers
and devices that connect to your network with wires.
For example, the Motorola Netopia MiAVo Series Gateways (www.netopia.com)
include a built-in DSL modem, a router, a wireless access point, and other networking
features such as a firewall and an easy-to-use graphical user interface
(GUI) for configuring and setting up the gateway.
Not many of these devices are on the market; you can’t buy many of them offthe-
shelf, but you can get them directly from your broadband service provider.
The term gateway gets used a lot by different folks with different ideas about
what such a device is. Although our definition is the most common (and, in
our opinion, correct), you may see some vendors selling devices that they
call Internet gateways that don’t have all the functions we describe.