Wireless computer networks have been around for a long time. Most have
been based on radio wave technology, but some have used optical or
infrared beams instead.
One of the earliest successful implementations,
in place as early as 1970, was the "Aloha" network at the University of
Hawaii. It used conventional radio-frequency transmitters and receivers
to span distances between cities and Islands in Hawaii.
Of course, in order for computers to participate in any network, they
must all agree on the precise meaning of the signals they exchange.
Every detail of the radio or infrared beams that they exchange must be
defined so that they can be translated into meaningful, unambiguous
bits and bytes.
When groups of people get together to seek agreement on these details,
they produce "Protocol Documents" that serve as guidelines for others.
The most successful protocols are generally sponsored by influential
trade associations or governments.
Since the early days of the "Aloha" network, the Wireless Networking
industry has seen the rise of several protocols that have become
popular, and as the science of computer networking has evolved, the
most important and popular protocols have coalesced into a rich group
of technologies that can interoperate with one another to varying
degrees. These are generally known as the "WiFi" protocols.
The earliest "WiFi" networks used a protocol from the Institute of
Electrical and Electronic Engineers (IEEE). The committee responsible
for that work named it "Protocol 802.11" back in 1997, but it didn't
become popular until 1999, when two newer, enhanced versions were
created. These were named "802.11A" and "802.11B".
The "B" variant began to dominate, but as vendors began developing and
selling related equipment, they found that consumers were reluctant to
buy their devices until they were assured of compatibility across
brands. Nobody wanted to buy network equipment without assurance that
it would be supported into the future and that it would continue to
work as other vendors entered the marketplace. An industry alliance was
formed to evaluate and publish compatibility. The group felt that the
old protocol names were too complicated, so they chose the nickname
"WiFi", and they began to publish lists of equipment that could
As technology has advanced, newer versions of the 802.11 protocol
family have been published. Today's networks, based on Protocols
802.11g and 802.11n, can exchange information much faster and farther
than the originals. The committees responsible for these new protocols
made sure that they included provisions for communicating with older
equipment by "falling back" to older, slower technologies when they
encountered them on the same network. Thus the new 802.11n protocol
knows how to slow down and communicate with older 802.11g equipment,
and 802.11g equipment knows how, in turn, to slow down and communicate
with 802.11b equipment.
Today, the "WiFi" logo enjoys a very good reputation. When present on a
piece of network equipment, it indicates that the vendor has paid the
WiFi Alliance to test and certify that the equipment works as
advertised, and that it can be used with other WiFi equipment from
other vendors. As a general rule today, consumers trust that any
network equipment advertising "WiFi" compatibility can be purchased,
installed, configured, and used with confidence in combination with
other WiFi equipment, regardless of the underlying protocol details.
However, today's consumers will find 802.11b, 802.11g, and 802.11n
equipment for sale on the same store shelves. Some vendors don't pay
for WiFi certification, so the WiFi logo may not be present, even on
good equipment that will interoperate according to the standards.
Informed consumers can make better purchase decisions if they are aware
of these basic protocol details.
802.11a: This older protocol isn't used very much, and there is little
guarantee that newer equipment will interoperate with it. It also
suffers from limited range (about 50 feet indoors). Some businesses
actually LIKE that because it can contribute to privacy and eliminate
certain problems related to radio interference, but there is little
reason for today's consumers to purchase this equipment.
802.11b: This older, slower, limited-range protocol remains very
popular, and it's the only popular wireless protocol that is compatible
with virtually everything. Speeds range between 1 and 11 million bits
per second, over distances of about 100 feet indoors or 300 feet
line-of-site. You won't find very much new network equipment that's
advertised as "802.11b" nowadays, but all of the newer items know how
to slow down to use it. If you have an old 802.11b laptop computer or
network adapter, you'll be able to use it at all public wireless
"hotspots" whenever you are within about 100 feet of the hotspot
antenna. Although 802.11 speed is too slow for High Definition local
video between your TV and adjacent PC, it's fast enough to fully
exploit your Internet connection. If you are just surfing the web or
exchanging email, you'll be fine with this. Skype telephony, and even
YouTube and Hulu video can be acceptable if you don't frustrate easily.
802.11g: This is similar to 802.11b, but it's 4 or 5 times as fast,
delivering up to 54 million bits per second over the same distances.
This is the dominant WiFi protocol at the time of this writing in 2009,
and equipment prices have fallen dramatically. With a carefully located
central antenna, a typical 802.11g router can serve the needs of most
consumers, reaching even the remote corners of a large American home
with performance that can fully exploit your Internet connection. Over
short distances (50 feet or so) it can deliver acceptable performance
between your TV, network disk drives, and PCs for audio and
standard-def video applications. Internet telephony and compressed,
Internet-based video services like YouTube and Hulu will probably be
fine all throughout your house at standard definition.
802.11n: Scientists have discovered that they can put multiple WiFi
transmitters and receivers into a single box, with multiple antennas,
and that they can even take advantage of radio "echos" and
"reflections" to transmit at higher speeds and over greater distances.
802.11n equipment takes advantage of this technology to achieve speeds
up to 10 times as fast as 802.11g, with distances that range up to 300
feet indoors or 600 feet line-of-site. At the time of this
writing in 2009, the WiFi alliance is certifying interoperability of
equipment from several vendors, based on a preliminary ("draft")
standard document that is pending final approval by the relevant IEEE
committees. Equipment prices are considerably higher than older
equipment, but because this effort has been so popular, it is likely
that future wireless equipment will continue to support that draft
standard, and it is generally considered safe and prudent to purchase
this equipment as part of a consumer network. With a carefully located
central antenna, a typical 802.11n router can serve high-definition
video and audio to TVs and PCs all throughout a large American home,
and Internet applications can be accessed throughout adjacent yards and
buildings at distances of 300 to 500 feet or beyond.
WiFi Network Equipment Types
If you go into any large technology retail store, you'll find shelves
loaded with various types of network equipment. As of this writing in
2009, the industry has reached general agreement on the names that they
apply to most of these items, based on either formal or informal
definitions of functions. Most of today's equipment combines several
separate functions into multiple-purpose boxes, but it's easier to
understand the situation if we first think about simple,
single-function devices. You'll find some of those too. Let's consider
those single-function devices first. You may find these items:
Broadband Modems: A - "Broadband Modem" - converts a DSL or Cable
Internet signal from a telephone or TV cable to computer-compatible
Ethernet. In its most basic sense, a Broadband Modem makes just ONE
Internet address available for use by a single computer in your home or
Routers: Routers are used to share a single Internet connection with
multiple computers. The most basic, single-function "Router" has 2
separate Ethernet Interfaces on 2 separate network segments. It uses
one of these 2 network segments to create a new, local, private LAN
subnet that can be expanded to connect with several computers in your
home or small office. It uses the other network segment to communicate
with your ISP on a Wide Area Network (WAN) through a single IP address. It multiplexes all outbound
Internet traffic from all of the local computers into that single ISP
IP address so that your Internet Service Provider thinks you have only
one computer sending data to the Internet, and when Internet traffic
comes back in response to that outbound traffic, the router
demultiplexes it and sends it back to the appropriate computer on the
LAN subnet. You can learn a lot more about Routers from videos in the
"Networking Fundamentals" section at AskMisterWizard.com. Pay
particular attention to the two videos entitled "NAT Routers Part 1"
and "NAT Routers Part 2".
Ethernet Switches: Ethernet Switches are used to expand a LAN subnet
for use with additional PCs. The most common, basic, single-function Ethernet
Switch has 5 or more Ethernet connectors, and each can be connected,
via an Ethernet Cable, to a separate computer, or to additional
Ethernet Switches for further expansion in - "daisy chain" -
fashion. All of the computers thus interconnected can then use
Ethernet protocols to exchange information. If those computers also
understand a higher-level networking protocol like IP, then their
Ethernet messages can also contain distinct IP addresses and IP
messages that a router can multiplex onto the Internet. Ethernet
Switches are closely related to Ethernet Hubs, and both technologies
can be used for the same purposes. You can learn a lot more about
Ethernet Hubs and Switches from additional videos, using those titles,
in our "Networking Fundamentals" section.
Wireless Access Points: A Wireless Access Point Receives Ethernet
traffic from a LAN segment and broadcasts it over radio waves, where it
can be picked up by computers equipped with Wireless Network
Adapters. A Wireless Access Point also receives radio messages
from those PCs, converting them into Ethernet messages and applying
them to the LAN segment. If those computers also understand a
higher-level networking protocol like IP, then their Ethernet messages
can also contain distinct IP addresses and IP messages that a router
can multiplex onto the Internet. Thus a Wireless Access Point is very
similar to an Ethernet Hub. You can see how we installed, configured,
and used a Wireless Access Point by watching the video entitled "Adding
a Wireless Access Point or 'Wireless Hub' to a wired Ethernet", which
is available in our "Networking Fundamentals" section.
Wireless Network Adapters: A Wireless Network Adapter contains WiFi
compatible radio transmitters and receivers, and converts those radio
signals to and from USB or PCI signals that are compatible with modern
personal computers. Sometimes these adapters are called "NICs", where
"NIC" stands for "Network Interface Card". Without some kind of
Wireless Network Adapters, a computer can't use a wireless network.
Most modern PCs come with Wireless Network adapters built-in. At the
time of this writing in 2009, most of these built-in, preconfigured
NICs are based on 802.11g technology, so if you want to use 802.11n
you'll probably need to pay extra for an external device. Operating
system compatibility can be an issue here, so be sure that the device
you purchase clearly advertises support for your chosen operating
system! You can see how we used a built-in Wireless Network Adapter in
a McDonald's fast-food restaurant to access a WiFi Hotspot by watching
the video entitled "McWireless: Wireless Internet Access at McDonalds",
which is available in our "Networking Fundamentals" section.
Wireless Ethernet Bridges: Wireless Ethernet Bridges, operating in
pairs or in conjunction with a Wireless Access Point, can interconnect
two separate Ethernet LAN segments.
For example, suppose a DSL Internet
connection enters a home office equipped with an appropriate router and
Ethernet Switch, where a printer and three separate computers reside:
Suppose that a distant bedroom at the opposite end of the same house
has 2 more computers and another printer, all plugged into a separate
We would say that this home has 2 separate Ethernet
LAN segments. The 2 computers in the bedroom could both use the bedroom
computer, but they couldn't use the office printer, or share its
It is possible to string a long Ethernet cable
between the office Ethernet Switch and the bedroom Ethernet Switch, but
usually it is more convenient to do this without wires.
By installing a
Wireless Access Point in the office and a Wireless Ethernet
Bridge in the bedroom, both LAN segments are joined.
Once the bedroom's
Wireless Ethernet bridge and the office's Access Point are configured
to communicate with one another, all 5 of the computers and both
printers can be given IP addresses from the same subnet and shared,
along with the Internet connection. Because modern console gaming
hardware like "X-Box" and "Playstation" generally contain wired
Ethernet connectors without any provision for WiFi, it is commonplace
to use them with a Wireless Ethernet Bridge. This functionality is
sometimes marketed as a "Wireless Game Adapter". Some Wireless Game
Adapters are specifically "crippled" with technology that prevents
their general-purpose use by PCs and other Ethernet devices, but most
are fully compatible and can bridge Ethernet LAN segments for use by
any kind of Ethernet equipment, in spite of their game-oriented names.
Wireless Print Servers: A Wireless Print Server allows you to share and
access your printer without wires. The most basic Wireless Print Server
would have a single USB or Parallel Printer port for connection with a
single, nearby printer, and a radio transceiver with antenna for
connection to a WiFi LAN through a nearby Wireless Access Point. It
converts the appropriate radio signals into printer commands and data
so that the printer can be located at any convenient place within WiFi
radio range of the Wireless Access Point. Today's basic Printer Servers
understand the IP protocol and are able to receive and interpret IP
messages containing printer data so that IP-equipped computers
throughout the home or small office can share the printer, even if the
printer was not originally designed with WiFi in mind. If the home or
small office router is appropriately enhanced with "Port Forwarding",
it is even possible for the printer to receive and handle printing
instructions from all over the Internet. You can learn a lot more about
"Port Forwarding" from the video segment entitled "NAT Routers Part 3:
Port Forwarding", which is available in the "Networking Fundamentals"
section at AskMisterWizard.com.
It is commonplace to combine two or more of the individual functions
described above into a single box. When manufacturers do this, the
functional lines often overlap or blur, resulting in the possibility of
confusion when they choose names for the resulting equipment.
Unfortunately, manufacturers tend to use the simple term "Router" for
most of these combinations, so you'll need to study the published
details to figure out the exact combination they are offering. A
careful reading of the retail packaging is generally sufficient. Here
are some of the combinations in common use today:
Router and Ethernet Switch: Almost all consumer-grade routers today
include an Ethernet Switch with 4 or more Ethernet connectors. Thus, at
the back of the router, you'll generally see 5 Ethernet jacks. One will
be labeled separately, and it will reference an "Internet" or
"Internet-Facing" or "Upstream" or "Wide Area" connection. Connect that
to your Broadband modem. The others will be grouped together, and an
associated label will reference "LAN" or "Local" or "Downstream"
connections. Use Ethernet cables to connect those to one or more PCs,
printers, etc. Manufacturers will almost always use the name "Router"
to describe this combination, and the general expectation is that any
basic router will include a basic Ethernet Switch.
Router, Ethernet Switch, and Wireless Access Point: This combination is
the same as "Router and Ethernet Switch", but it adds a Wireless Access
Point so that you can connect one or more computers via WiFi in
addition to those connected with Ethernet. You can use any practical
combination of Ethernet and/or WiFi connections. Manufacturers
generally use the name "WiFi Router" to describe this combination. It
is also possible to bypass the Router portion of this kind of
equipment, if you only need Ethernet Switch and/or Wireless Access
Modem, Router, and Switch: If you obtain your basic router from your
Internet Service Provider, it will probably include modem logic that's
compatible with their DSL or Cable connection. Like other routers, this
logic almost always includes a 4-port Ethernet Switch, so you can
connect it with 4 computers before you'll need to expand your Ethernet
LAN subnet. This combination doesn't include a Wireless Access point,
so every connection will be wired. Manufacturers are split on the name
of this combination: sometimes they call it a "Broadband Modem", and
sometimes they call it a "Router". Sometimes they call it a
Modem, Router, Ethernet Switch, and Wireless Access Point: If you pay a
premium to your Internet Service Provider you can get this
all-inclusive combination. The modem logic will be compatible with the
particular broadband technology supported by your ISP (DSL or Coaxial
Cable). The Router will create a new IP subnet on which you can share
your single Internet Address with several computers. The Ethernet
Switch will expand that new subnet with several physical Ethernet
connectors for wired PCs, and the Wireless Access Point will allow
shared radio access to the resulting LAN segment. You can also buy
these devices from retailers, but be sure to check the specs on the
modem. Some support Cable only, some support DSL only, and some support
both. Most manufacturers describe this combination as a "WiFi Router".
Sometimes they call it a "Wireless Residential Gateway".
Combining or "Daisy-Chaining" - Multiple Devices
It's commonplace to - "Daisy Chain" - several of these devices in
series. For example, if you were to obtain single-function boxes for
all of the above functions, you could hook them all to one another like
basic, logical flow (Modem, Router, Ethernet Switch, WiFi Access Point)
is retained regardless of whether the functional lines are contained
within 4 separate network boxes, or in a single box.
Here's an example of that same functionality housed in 2 separate boxes:
1- Modem, Router, and Ethernet Switch
2- Wireless Access Point.
Here's an implementation of the identical WiFi distribution architechture in 3 boxes:
2- Router and Ethernet Switch
3- Wireless Access Point
It is even commonplace to double-up some of those functions in the chain, like this:
1- Modem, Router, Ethernet Switch
2- Router, Ethernet Switch, Wireless Access Point
In this two-box case, TWO distinct, new subnets are created, and one is
logically closer to the Internet than the other. The innermost new
subnet, closer to the Internet, has wired access only, while the outer
subnet has both wired access (through the Ethernet Switch in the second
box) and WiFi Access. Managing two distinct IP subnets creates some
interesting security implications: Internet traffic from BOTH subnets
flows through the innermost one, and it can all be monitored by
sophisticated technicians attached to that innermost LAN. The outermost
LAN, however, never sees Internet traffic to or from the innermost LAN
(but both segments can see any traffic exchanged between the Inner LAN
and the outer LAN). You can learn a lot more about subnets and routers
from the video clips in our Networking Fundamentals section.