CompTIA exam study guide presentations by instructor Brian Ferrill, PACE-IT (Progressive, Accelerated Certifications for Employment in Information Technology) "Funded by the Department of Labor, Employment and Training Administration, Grant #TC-23745-12-60-A-53" Learn more about the PACE-IT Online program: www.edcc.edu/pace-it

1. Wireless LAN
infrastructure II.

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Instructor, PACE-IT Program – Edmonds Community College
Areas of expertise Industry Certifications
 PC Hardware
 Network Administration
 IT Project Management
 Network Design
 User Training
 IT Troubleshooting
Qualifications Summary
Education
 M.B.A., IT Management, Western Governor’s University
 B.S., IT Security, Western Governor’s University
Entrepreneur, executive leader, and proven manger
with 10+ years of experience turning complex issues
into efficient and effective solutions.
Strengths include developing and mentoring diverse
workforces, improving processes, analyzing
business needs and creating the solutions
required— with a focus on technology.

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PACE-IT.
– Basic WLAN topologies.
– WLAN concepts and terms.

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Wireless LAN infrastructure II.

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Wireless LAN infrastructure II.
– Ad hoc topology.
» A very basic wireless local area network (WLAN) that
does not require the use of a wireless access point
(WAP)—also known as an access point (AP).
» Devices negotiate the wireless connection between
themselves (e.g., laptops connect wirelessly without the
use of a WAP).
– Infrastructure topology.
» A more common type of WLAN that uses a WAP or
WAPs to create a connection point for wireless devices.
• Most often connects a WLAN to a more traditional wired
network, but it is not absolutely required.
– Mesh topology.
» A type of infrastructure topology that employs the use of
multiple APs to create a larger seamless network
coverage area.
• Commonly deployed with wireless controllers and
WAPs.

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Something to remember is
that the higher the wireless
device density, the more
WAPs that will be required
to handle the load.
Like any other network device, APs only have a
certain amount of capacity. As the workload
increases, the amount of throughput will decrease
as each device contends for access to the WAP.
Adding more WAPs and/or adding more WAPs and
a wireless controller can greatly ease the load and
increase the efficiency of the network.
Wireless LAN infrastructure II.

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Wireless LAN infrastructure II.

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Wireless LAN infrastructure II.
IBSS.
Independent basic
service set.
An IBSS is created when an ad hoc
network topology is created. The
devices use the IBSS in order to
control the communication that
occurs between connected devices.
BSS.
Basic service set.
When a single WAP is in
infrastructure mode, it will create a
BSS. This means that it can control
the flow of communication between
every device that connects to the
SSIDs under its control.
ESS.
Extended service set.
An ESS is created when two or
more APs share a common SSID
and have overlapping coverage.
Through the ESS, the WAPs will
negotiate how to hand off a wireless
device between them as it roams the
network.

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The service set identifier
(SSID) plays a key role in
the WLAN environment.
All active WAPs will use a beacon transmission to advertise the
networks that they belong to. What they advertise is their
SSIDs—their network names. Those beacons are how devices
know which networks they can connect to.
Even when the AP is set to hide the beacon, the broadcasts are
still occurring. Although hiding the SSID broadcast may make it
more difficult to join a wireless network, it is not a true security
measure.
Wireless LAN infrastructure II.

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Wireless LAN infrastructure II.
– 802.11a-ht and 802.11g-ht.
» Both terms relate to the 802.11n standard.
• Denote the type of connection—high throughput, and the
radio frequency—either 2.4 GHz or 5GHz of the connection.
– Goodput.
» The actual amount of application data passed through a
connection with the overhead removed, measured in bytes per
second.
» It is different than throughput.
• Throughput measures the total amount of data capable of
being passed through a connection.
– Signal strength.
» A measure of the strength of the RF signal from an AP, which
can help to determine coverage area.
• As a general rule, the closer a device is to the WAP, the
stronger the signal received.
» The strength of a signal can be affected by WAP or antenna
placement, type of antenna, and interference sources, etc.

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A wireless site survey with
heat mapping tools can help
in the set up of a WLAN or it
can help to pinpoint problem
areas.
Heat mapping software builds a visual map by
measuring received signal strength indicator (RSSI)
and signal to noise ratio (SNR), which can be
directly correlated to data throughput.
Using these tools allows the administrator to find
gaps in coverage as well as areas where the
coverage extends beyond the desired boundaries.
Wireless LAN infrastructure II.

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Wireless LAN infrastructure II.
In an ad hoc network, wireless devices connect without an AP, using an
IBSS. In an infrastructure network, one or more WAPs control access to the
network through a BSS. A mesh network is a type of infrastructure wireless
network that uses multiple APs to seamlessly provide network coverage
over a larger area through the use of an ESS. As device density increases,
more WAPs can be added to distribute the load.
Topic
Basic WLAN topologies.
Summary
WAPs send out a beacon that contains the SSID (the network name).
Hiding the SSID doesn’t stop the beacon from being broadcast and is not
an effective security measure. Goodput is a measure, in bytes per second,
of actual application data that can be transmitted. The closer to the AP that
a wireless device gets, the stronger the signal. Site surveys and heat maps
can be used to set up efficient wireless networks and to pinpoint problem
areas.
WLAN concepts and terms.

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THANK YOU!

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