What is Wireless Networking?
What is a wireless network made up of?
What is IEEE 802.11?
Can I mix wireless equipment from different
vendors?
If my computer is connected to a wireless LAN, can
it communicate with computers on a wired LAN as well?
How many wireless networked computers can use a
single access point?
Can I have more than one access point?
What is Roaming?
Can I use a wireless network to interconnect two
LANs?
Is it true that wireless networking is only good
for laptop computers?
What about security?
How can I use a wireless network to share an
Internet connection?
If I have more than one hardware access point,
how can I share a single Internet connection?
If I use a wireless network to connect to the
Internet does my ISP need a wireless network too?
The term wireless networking refers to technology that enables two or
more computers to communicate using standard network protocols, but without
network cabling. Strictly speaking, any technology that does this could be
called wireless networking. The current buzzword however generally refers to
wireless LANs. This technology, fuelled by the emergence of cross-vendor
industry standards such as IEEE 802.11, has produced a number of affordable
wireless solutions that are growing in popularity with business and schools
as well as sophisticated applications where network wiring is impossible,
such as in warehousing or point-of-sale handheld equipment.
References:
802.11 Tutorial
Back to Top
There are two kinds of wireless
networks:
1) An ad-hoc, or peer-to-peer wireless network consists of a number
of computers each equipped with a wireless networking interface card.
Each computer can communicate directly with all of the other wireless
enabled computers. They can share files and printers this way, but may
not be able to access wired LAN resources, unless one of the computers
acts as a bridge to the wired LAN using special software. (This is
called "bridging")
Picture 1: Ad-Hoc or Peer-to Peer Networking.
Each computer with a wireless interface can communicate directly with
all of the others.
2) A wireless network can also use an access point, or base station.
In this type of network the access point acts like a hub, providing
connectivity for the wireless computers. It can connect (or "bridge")
the wireless LAN to a wired LAN, allowing wireless computer access to
LAN resources, such as file servers or existing Internet Connectivity.
There are two types of access points:
a. Dedicated hardware access points such as
Proxim,
Colubris,
Alvarion,
Cisco,
Zyxel. (See
Picture 2). Hardware access points offer comprehensive
support of most wireless features, but check your requirements
carefully.
b. Software Access Points which run on a computer equipped with a
wireless network interface card as used in an ad-hoc or peer-to-peer
wireless network. (See Picture 3)
With appropriate networking software support, users on the wireless
LAN can share files and printers located on the wired LAN and vice
versa.
Picture 2: Hardware Access Point.
Wireless connected computers using a Hardware Access Point.
Picture 3: Software Access Point.
Wireless connected computers using a Software Access Point.
Back to Top
Wireless networking hardware requires the use of
underlying technology that deals with radio frequencies as well as data
transmission. The most widely used standard is 802.11 produced by the
Institute of Electrical and Electronic Engineers (IEEE). This is a standard
defining all aspects of Radio Frequency Wireless networking.
Back to Top
Because most wireless networking hardware vendors support the 802.11
standard they can inter operate. However, it''''s recommended verification as the
standard is a fairly recent one, and does specify two different methods for
wireless communications; Frequency Hopping (FH) and Direct Sequence Spread
Spectrum (DSSS or DS), which are not interoperable.
When purchasing wireless networking hardware from separate vendors be
sure to obtain guarantees from the vendors that the hardware will
interoperate and follows the standards.
Within a short time we expect all new wireless cards, like ethernet
cards, to become inexpensive, ubiquitous and totally interoperable.
Also of note is that the latest version of the standard defines 11mbps
and 5.5mbps networking, with support for the older standard 1mbps and 2mbps
speeds. This provides some compatibility with different or older equipment.
Note that this new standard covers DS-type Networks, not FH types.
Software access points such as the Internet Gateway which uses the
wireless interface of the host computer should have no compatibility issues
with third party wireless hardware, as long as standards are followed.
Typically wireless hardware is identified to the software as a network
interface, and therefore can be used in the same way as any other network
card.
Back to Top
To do this you will need some sort of bridge between the wireless and
wired network. This can be accomplished either with a hardware access point
or a software access point. Hardware access points are available with
various types of network interfaces, such as Ethernet or Token Ring, but
typically require extra hardware to be purchased if your networking
requirements change.
If networking requirements go beyond just interconnecting a wired network
network to a small wireless network, a software access point may be the best
solution.
A software access point does not limit the type or number of network
interfaces you use. It may also allow considerable flexibility in providing
access to different network types, such as different types of Ethernet,
Wireless and Token Ring networks. Such connections are only limited by the
number of slots or interfaces in the computer used for this task.
Further to this the software access point may include significant
additional features such as shared Internet access, web caching or content
filtering, providing significant benefits to users and administrators.
Back to Top
This depends upon the manufacturer. Some hardware access points have a
recommended limit of 10, with other more expensive access points supporting
up to 100 wireless connections. Using more computers than recommended will
cause performance and reliability to suffer.
Software access points may also impose user limitations, but this depends
upon the specific software, and the host computer''''s ability to process the
required information.
Back to Top
Yes, multiple access points can be connected to a wired LAN, or sometimes
even to a second wireless LAN if the access point supports this.
In most cases, separate access points are interconnected via a wired LAN,
providing wireless connectivity in specific areas such as offices or
classrooms, but connected to a main wired LAN for access to network
resources, such as file servers. (See Picture 4)
Picture 4: Multiple Access Points.
Wireless connected computers using Multiple Access Points.
If a single area is too large to be covered by a single access point,
then multiple access points or extension points can be used. -- Note that an
"extension point" is not defined in the wireless standard, but have been
developed by some manufacturers. When using multiple access points, each
access point wireless area should overlap its neighbors. This provides a
seamless area for users to move around in using a feature called "roaming. "
(See the next question for an explanation of Roaming)
Back to Top
A wireless computer can "roam" from one access point to another, with the
software and hardware maintaining a steady network connection by monitoring
the signal strength from in-range access points and locking on to the one
with the best quality. Usually this is completely transparent to the user;
they are not aware that a different access point is being used from area to
area. Some access point configurations require security authentication when
swapping access points, usually in the form of a password dialog box.
Access points are required to have overlapping wireless areas to achieve
this as can be seen in the following diagram:
Picture 6: Roaming.
A user can move from Area 1 to Area 2 transparently. The Wireless networking
hardware automatically swaps to the Access Point with the best signal.
Not all access points are capable of being configured to support roaming.
Also of note is that any access points for a single vendor should be used
when implementing roaming, as there is no official standard for this
feature.
Back to Top
Yes. Wireless networking offers a cost-effective solution to users with
difficult physical installations such as campuses, hospitals or businesses
with more than one location in immediate proximity but separated by public
thoroughfare. This type of installation requires two access points. Each
access point acts as a bridge or router connecting its own LAN to the
wireless connection. The wireless connection allows the two access points to
communicate with each other, and therefore interconnect the two LAN''''s.
Picture 7: LAN to LAN Wireless Communications
A Hardware Access Point providing wireless connectivity to local computers
and a software access point. The software access point provides Wired
Ethernet network 2 computers access to Wired Network 1.
Note that not all hardware access points have the ability to directly
interconnect to another hardware access point, and that the subject of
interconnecting LAN''''s over wireless connections is a large and complex one,
and is beyond the scope of this introduction. See the reference links at the
end of this section if you require further information.
Back to Top
Although wireless networking offers obvious benefits to users of laptops
who move from location to location throughout the day, there are benefits
for users of fixed position computers as well:
Many schools and businesses have unsuitable building layouts or walls
that cannot be wired for various reasons making it difficult or impossible
to build a wired network. Wireless networking in these environments is a
very cost effective alternative also providing future flexibility.
In cases where a small number of computers are separated from a main
network a wireless link may be more cost effective than network cabling
although the latter is perfectly feasible.
Temporary wireless LANs can easily be created for exhibitions, school or
business projects, all without any trailing cabling.
Back to Top
Wireless communications obviously provide potential security issues, as
an intruder does not need physical access to the traditional wired network
in order to gain access to data communications. However, 802.11 wireless
communications cannot be received --much less decoded-- by simple scanners,
short wave receivers etc. This has led to the common misconception that
wireless communications cannot be eavesdropped at all. However,
eavesdropping is possible using specialist equipment.
To protect against any potential security issues, 802.11 wireless
communications have a function called WEP (Wired Equivalent Privacy), a form
of encryption which provides privacy comparable to that of a traditional
wired network. If the wireless network has information that should be secure
then WEP should be used, ensuring the data is protected at traditional wired
network levels.
Also it should be noted that traditional Virtual Private Networking (VPN)
techniques will work over wireless networks in the same way as traditional
wired networks.
References:
Wireless LAN security
Back to Top
Wireless Networking and the Internet
Once you realise that wireless cards are analogous to ethernet cards and
that empty space is analogous to ethernet cabling, the answer to this
question becomes clear. To share an Internet connection across a LAN you
need two things:
- an Internet sharing hardware device or software program
- a LAN
If your LAN is wireless, the same criteria apply. You need a hardware or
software access point and a wireless LAN. Any computer equipped with a
wireless network card running suitable Internet sharing software can be used
as a software access point. (See Picture 8) A number of vendors offer
hardware access points.
A hardware access point may provide Internet Sharing capabilities to
Wired LAN computers, but does not usually provide much flexibility beyond
very simple configurations. (See Picture 9)
Picture 8: Software Access Point.
Wireless connected computers using a Software Access Point for shared
Internet access.
Picture 9: Hardware Access Point.
Wireless connected computers using a Hardware Access Point for shared
Internet access.
Back to Top
If an existing wired LAN already has an Internet connection, then the
hardware access points simply connect to your LAN and allow wireless
computers to access the existing Internet connection in the same way as
wired LAN computers.
Picture 10: Multiple Access Points.
Wireless connected computers using Multiple Access Points.
If there is no existing Internet connection, then this depends on the
access point:
Picture 11: Software Access Point sharing one Internet connection.
Wireless connected computers using Multiple Access Points. All wired and
wireless computers access the Internet through a single software access
point.
If an access point provides some form of Internet sharing itself, then
having multiple such access points connected to a wired LAN may require some
special configuration, or possibly may require an additional Internet
sharing device or software program.
Back to Top
If you use a wireless network to connect to the Internet, the wireless
part only concerns your LAN. The communications link from your LAN to your
Internet service provider (ISP) would be identical whether or not you had a
wireless network. For example, if you connected an Ethernet network to the
Internet via a 56K modem, when you upgraded your network to use wireless,
you would still use the same 56K modem to connect to the Internet.
Back to Top
Wireless cards look just like Ethernet cards to your network drivers. In
fact, wireless networking cards have unique MAC hardware addresses that are
formatted like Ethernet hardware addresses allocated from the same standards
organization.
Back to Top