Transcript New Kids on the Block: Linux

Wireless LAN Technology for
SOHO
Instructor: Professor Mort Anvari
Presented by: Yanfeng Wang
Jie Lin
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Road Map
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What is a wireless LAN
Advantage of wireless LAN
Hardware Requirement
WLAN Model
Standards
Issues to Be Solved
Future
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What Is A Wireless LAN (WLAN)?
• A Wireless LAN is a LAN without
conventional network cabling.
• It is a flexible network that can either
replace or extend a wired LAN to provide
added functionality.
• It relies on radio frequencies (RF) to
transmit and receive data between
computers.
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Advantages of WLAN---Mobility
• Users can move around and still
remain connected to the network
– It gives users greater flexibility to move
computers anywhere in home or office and still
have them be networked.
– Networking computers in different rooms or on
different floors might need the convenience of a
WLAN.
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Advantages of WLAN: Reliability
• Cable fault is completely eliminated!
– Wired network maybe reliable, but cable faults
is still a problem, which can cripple network
traffic, and tracking them down can take many
hours.
• Cables break makes metallic conductors rust or
allow water to enter
• Staff members accidentally cut cables
• Workers do a shoddy job of splicing
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Advantages of WLAN: Cost
• Sometimes cabling is too costly or
impossible
– cabling between buildings can be expensive
– impossible due to structural hurdles or digging
restrictions
• Long-term cost concerns: Recabling can be
expensive, time-consuming, disruptive.
– Company Reorganization moves employee around,
reconfigure offices, and add new buildings.
– Home Renovation:Children move out, Adult switch
around, add rooms or initiate remodeling projects.
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A Wireless LAN
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Hardware Requirement
• Wireless NIC and PCMCIA
• Wireless Hub (Access Point)
• Wireless Bridge
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Wireless NIC/PCMCIA
– Wireless adapters are made in the same form
factors as their wired counterparts - PCI,
PCMCIA, and USB.
– Adapters for wired LAN provide the interface
between the network operating system and the
wire.
– Adapters for WLAN provide the interface
between the network operating system and an
antenna, to create a transparent connection to
the network.
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Wireless NIC/PCMCIA
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Wireless Hub (Access Point)
• Access Point is the wireless equivalent of a
LAN hub.
• It use antenna to receive, buffer and
transmit data among the member computers
of a WLAN
• An Access Point can be connected with the
wired backbone through standard Ethernet
cable.
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Wireless Hub (Access Point )
• Like the cells in a cellular phone network,
multiple Access Points can support roaming
from one Access Point to another as the user
moves from area to area
• Access Points have ranges from 20
meters to 500 meters
• A single Access Point can support 15 to
250 users, depending on the technology
and configuration.
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Wireless Hub (Access Point)
• It is easy to scale up WLANs by adding
more Access Points, which decreases
network congestion and enlarges the
coverage area.
• Large facilities require deployment of
multiple Access Points to create
overlapping cells for constant
connectivity to the network.
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A Wireless Hub (Access Point)
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Wireless LAN Bridge
• Outdoor LAN bridges connect LANs in
different buildings.
– highways
– bodies of water
• It provides a less expensive alternative to
recurring leased-line charges.
– It supports fairly high data rates and ranges of several
miles with the use of line-of-sight directional antennas.
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Wireless LAN Bridges
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WLAN-Peer to Peer Model
• It consists of two or more PCs equipped
with wireless NICs, but with no connection
to a wired network.
• It is principally used to quickly and easily
set up a WLAN where no infrastructure is
available
– a convention center
– a trade fair
• No Access Point is needed.
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Peer to Peer Model
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WLAN-Client/Server Model
• It typically consists of multiple computers
(both the servers and the clients) equipped
with wireless NICs and an Access Point that
acts as a traffic center of the WLAN
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Client/Server Model
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Mixed Model
• Wired LAN and wireless LAN are not
mutually exclusive.
• Wired LANs and wireless LANs can join
seamlessly.
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Mixed Model
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Price: Current Not for shallow pockets
• Expensive compared to wired LAN
– Wireless NIC:
$40 up
– Wireless PCMCIA: $100 up
– Wireless Hub:
$200 up
• Don’t worry, it is quickly dropping!
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Where To Buy?
• Electric Appliance Retailers:
– BestBuy, Circuit City, CompUSA
• Online Retail Stores:
– buy.com, egghead.com
• Manufacturer’s Online Store
– sohoware.com, cisco.com
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Major Hardware Manufacturers
Intel
Cisco
3Com
Lucent
Netgear
SOHOWare
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Standards---802.11
• Like all IEEE 802 standards, the 802.11
standard focuses on the bottom two levels
of the ISO model, the physical layer and
data link layer.
• Any LAN application, network operating
system or protocol, including TCP/IP, will
run on 802.11 compliant WLANs as easily
as they run over Ethernet.
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Potential for Improvement
• Predictability:
– Walls, large appliances, and other obstacles can
interfere with the propagation of radio waves,
degrading the network’s performance.
• Security:
– with the network access code, anyone within the
broadcast area can eavesdrop on network
communications.
• Speed:
– The current speed of 1Mbps to 11Mbps makes it
difficult to stream video across wireless network and
get good results.
– Results with audio are better, but still not optimum.
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Future Growth
• 75 percent of large organizations are evaluating
WLANs
• More than 90 percent of all communications
traffic consists of data and not voice, which
represents a huge potential of growth for wireless
data communication.
• Laptops now make up about 25 percent of
corporate purchases (Intel Corporate Market
Research, 2000).
• Analysts agree that the WLAN market is set to
reach $1.6 to $2.2 billion by 2005.
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Summary
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It is there!
It is nice!
It’s cost is quickly dropping!
It’s the direction of the future!
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