- What is wireless networking?
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.
- What is a wireless network made up of?
There are two kinds of wireless networks:
- 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")
Figure 1: Ad-Hoc or Peer-to Peer Networking.
Each computer with a wireless interface can communicate directly
with all of the others.
-
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:
-
Dedicated hardware access points (HAP) such as Lucent's
WaveLAN, Apple's Airport Base Station or WebGear's AviatorPRO.
(See Figure 2). Hardware
access points offer comprehensive support of most wireless
features, but check your requirements carefully.
-
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
Figure 3) The Vicomsoft InterGate suites are software
routers that can be used as a basic Software Access Point,
and include features not commonly found in hardware solutions,
such as Direct PPPoE support and extensive configuration flexibility,
but may not offer the full range of wireless features defined
in the 802.11 standard.
With appropriate networking software support, users
on the wireless LAN can share files and printers located on the wired
LAN and vice versa. Vicomsoft's solutions support file sharing using
TCP/IP.
Figure 2: Hardware Access
Point.
Wireless connected computers using a Hardware Access Point.
Figure 3: Software Access
Point.
Wireless connected computers using a Software Access Point.
- What is IEEE 802.11?
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.
- Can I mix wireless equipment from different vendors?
Because most wireless networking hardware vendors support the 802.11
standard they can inter operate. However, we recommend 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 InterGate 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.
- If my computer is connected to a wireless LAN, can
it communicate with computers on a wired LAN as well?
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.
- What is the range of a wireless network?
Each access point has a finite range within which a wireless connection
can be maintained between the client computer and the access point.
The actual distance varies depending upon the environment; manufacturers
typically state both indoor and outdoor ranges to give a reasonable
indication of reliable performance. Also it should be noted that when
operating at the limits of range the performance may drop, as the
quality of connection deteriorates and the system compensates.
Typical indoor ranges are 150-300 feet, but can be shorter if the
building construction interferes with radio transmissions. Longer
ranges are possible, but performance will degrade with distance.
Outdoor ranges are quoted up to 1000 feet, but again this depends
upon the environment.
There are ways to extend the basic operating range of Wireless communications,
by using more than a single access point or using a wireless relay
/extension point. See Question
8 for further information.
- How many wireless networked computers can use a single
access point?
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.
- Can I have more than one access point?
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
Figure 4)
Figure 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)
Some manufacturers produce extension points, which act as wireless
relays, extending the range of a single access point. Multiple extension
points can be strung together to provide wireless access to far away
locations from the central access point. (See
Figure 5)
Figure 5: Extension Point.
Wireless connected computers using an Access Point with an Extension
Point.
- What is Roaming?
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:
Figure 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.
- Can I use a wireless network to interconnect two LANs?
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.
Figure 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.
- Is it true that wireless networking is only good for
laptop computers?
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.
- What about security?
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.
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