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Wi-Fi Devices:
Wireless Access Point (WAP)
A wireless access point (AP)
connects a group of wireless stations to an adjacent wired local area network
(LAN). An access point is similar to an ethernet hub or switch, but instead of
relaying LAN data only to other LAN stations, an access point can relay
wireless data to all other compatible wireless devices as well as to a single
(usually) connected LAN device, in most cases an ethernet hub or switch,
allowing wireless devices to communicate with any other device on the LAN.
Wireless Routers
A wireless router integrates a
wireless access point with an IP router and an ethernet switch . The integrated
switch connects the integrated access point and the integrated ethernet router
internally, and allows for external wired ethernet LAN devices to be connected
as well as a (usually) single WAN device such as cable modem or DSL modem . A
wireless router advantageously allows all three devices (mainly the access
point and router) to be configured through one central configuration utility,
usually through an integrated web server .
Wireless Ethernet
Bridge
A wireless Ethernet bridge
connects a wired network to a wireless network. This is different from an
access point in the sense that an access point connects wireless devices to a
wired network at the data-link layer . Two wireless bridges may be used to
connect two wired networks over a wireless link, useful in situations where a
wired connection may be unavailable, such as between two separate homes.
Advantages of Wi-Fi
Allows LANs to be deployed
without cabling, typically reducing the costs of network deployment and
expansion. Spaces where cables cannot be run, such as outdoor areas and
historical buildings, can host wireless LANs.
Wi-Fi silicon pricing continues
to come down, making Wi-Fi a very economical networking option and driving
inclusion of Wi-Fi in an ever-widening array of devices.
Wi-Fi products are widely
available in the market. Different brands of access points and client network
interfaces are interoperable at a basic level of service. Products designated
as Wi-Fi CERTIFIED by the Wi-Fi Alliance are interoperable and include WPA2
security.
Wi-Fi networks support roaming,
in which a mobile client station such as a laptop computer can move from one
access point to another as the user moves around a building or area.
Wi-Fi networks support roaming,
in which a mobile client station such as a laptop computer can move from one
access point to another as the user moves around a building or area.
Wi-Fi is a global set of
standards. Unlike cellular carriers, the same Wi-Fi client works in different
countries around the world.
Disadvantages of Wi-Fi
Wi-Fi can be interrupted by other
devices, notably 2.4 GHz cordless phones and microwave ovens.
Power consumption is fairly high
compared to some other standards, making battery life and heat a concern.
The most common wireless
encryption standard, Wired Equivalent Privacy or WEP, has been shown to be
breakable even when correctly configured.
Wi-Fi Access Points typically
default to an open ( encryption -free) mode. Novice users benefit from a zero
configuration device that works out of the box but might not intend to provide
open wireless access to their LAN.
Wi-Fi networks have limited
range. A typical Wi-Fi home router using 802.11b or 802.11g with a stock
antenna might have a range of 45 m (150 ft) indoors and 90 m (300 ft) outdoors.
Range also varies with frequency band, as Wi-Fi is no exception to the physics
of radio wave propagation. Wi-Fi in the 2.4 GHz frequency block has better
range than Wi-Fi in the 5 GHz frequency block, and less range than the oldest
Wi-Fi (and pre-Wi-Fi) 900 MHz block. Outdoor range with improved antennas can
be several kilometres or more with line-of-sight.
Wi-Fi networks can be monitored
and used to read and copy data (including personal information) transmitted
over the network when no encryption such as VPN is used.