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Wireless Network
Access Point Tips and Advise !
Wireless
Network Access Point
A wireless access point (WAP or AP) is a device
that "connects" wireless communication devices together to create
a wireless network. A wireless access point acts as the network's
arbitrator, negotiating when each nearby client device can
transmit. The WAP is also usually connected to a wired network,
and can relay data between devices on each side. Many access
points can be connected together to create a larger network that
allows "roaming" where a person using the network can move from
the communication range of one WAP to another and experience no
data loss. One of the most common AP types is the 802.11 or
"Wireless Ethernet" access point connecting an Ethernet network to
so-called "Wi-Fi" devices, but other devices (such as those
connecting mobile phones to wired phone networks) can also be
considered WAPs. In Wi-Fi parlance, a network with at least one
active wireless access point doing its duty is said to be a
managed network or an inf rastructure
network. In contrast, a network where the client devices manage
themselves is called an ad-hoc network.
Wireless access points with easy installation and low cost (at
first glance) rapidly grew in popularity in the late 1990s and
early 2000s. These devices offered a way to avoid tangled messes
of Category 5 cable associated with typical Ethernet networks of
the day. While wiring a business, home, or school often requires
stringing many cables through walls and ceilings, wireless
networking offers the ability to cut down on the number of cables
strung or, in some cases, remove them entirely. Wireless networks
also give users greater mobility freeing individuals from the need
to be stuck at a computer tied to the wall. On the industrial and
commercial side, wireless networking has had a big impact on
operations: employees are often armed with Portable Data Terminals
having barcode scanners and wireless links, allowing them to
update work progress and inventory in real-time.
One 802.11 access point can typically communicate with 30 client
systems within a radius of anywhere from 50 to 300 feet. However,
communication range varies a lot in the wireless world. General
placement (indoor, outdoor, height above ground, nearby
obstructions, etc.) is one very major variable. Other issues
include the type of antenna, the current weather, operating radio
frequency, and power output of the device. Some experiments have
been carried out to allow computer networking over distances of
several miles or more (though such placement is not unusual for
cellular systems).
A typical corporate use of WAPs is to attach one to the wired
network and then provide wireless client adapters for users who
need them. Within the range of the access point, the wireless
end-user has a full network connection with the benefit of
mobility. In this instance, the access point is a gateway for
clients to access the network. Another use is to bridge two wired
networks where cable is not appropriate; for example, a
manufacturer can connect a remote warehouse (within line of sight)
by radio, with a wired network in each facility.
Another topography is called a lily pad network: a series of
access points spread over a large area, each connected to a
different network, providing hot spots where wireless clients can
connect to the Internet without regard for the particular networks
to which it's attached at the moment. The concept is somewhat
accidental in large cities, where a combination of coffeehouses,
libraries, and other public spaces offering wireless access allow
clients to roam over a large area (i.e., hopping from lily pad to
lily pad), staying more or less continually connected.
Additionally, the range of wireless access points can be extended
through the use of repeaters and reflectors, which can bounce
and/or amplify radio signals that ordinarily couldn't be received.
Usually, adjacent access points will use different frequencies to
communicate with their clients. This avoids interference between
the two nearby systems. However, wireless devices often take time
to "listen" for other data traffic in the area on different
frequencies, and are able to rapidly switch from one frequency to
another when moving into an area that has better reception on a
different AP. Unfortunately, this becomes problematic in crowded
areas such as downtown areas with tall buildings. There can be
enough overlap between the wireless networks of several businesses
to cause interference because there just aren't any more
frequencies available.
Wireless networking is far behind wired networking in terms of
bandwidth and throughput. While (as of 2004) typical wireless
devices for the consumer market can reach speeds of 11 (802.11b)
or 54 megabits per second (802.11a, 802.11g), wired hardware of
similar cost reaches 1000Mbps (Gigabit Ethernet). Networks that
existed before the advent of wireless still remain, or have even
been upgraded to higher bitrates, and there is desire to see
wireless networks increase in speed to keep up.
Another issue with wireless access in general is the need for
security. Many early access points did not have very good
abilities to discern if a particular user was authorized to access
the network or not. This problem reflects issues that have long
troubled many types of wired networks. It has been possible in the
past for individuals to plug computers into random available
Ethernet jacks and get access to the network. This was usually not
much of a problem, though, since many businesses had reasonably
good physical security. However, the fact that radio signals bleed
outside buildings and across property lines means that the
physical security aspect is not as much of a deterrent.
In response, several new security technologies have emerged. One
of the simplest techniques involves only allowing access from
certain MAC addresses, which works well in many cases. However,
MAC addresses can be easily spoofed, leading to the development of
more advanced measures. Many access points incorporate Wired
Equivalent Privacy encryption, but that has been decried by many
security analysts as not quite good enough (one common complaint
is: "Wired Equivalent Privacy isn't"). A newer system for
authentication is 802.1x, which promises to enhance security on
both wired and wireless networks. Access points that incorporate
technologies like these often also have routers built in, so they
are somewhat more accurately described as wireless gateways.
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