Download Wireless Networking

Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Networking
Chapter 15
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Objectives
• Explain wireless networking standards
• Describe the process for implementing Wi-Fi
networks
• Describe troubleshooting techniques
for wireless networks
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Historical/Conceptual
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Introduction to Wireless Networking
• Wireless network uses radio frequency (RF)
waves to communicate between devices
– Enables flexibility and mobility
– Uses the same OSI layers as wired networks
• Except first two OSI layers
– Differs from wired networking in type of media
and protocols for transmitting and accessing data
– The dominant wireless implementation is Wi-Fi
• IEEE 802.11 wireless Ethernet standard
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Test Specific
Wi-Fi Standards
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wi-Fi Standards
• Wi-Fi is by far the most widely adopted
wireless networking type today
• Wi-Fi technologies have been around since
the late 1990s
– Supported and standardized under the umbrella
IEEE 802.11 standard
– Examples of 802.11 amendments: 802.11g and
802.11 ac
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
802.11
• Standards define how wireless devices
communicate
– Also address communication security
• 802.11 established the baseline features
common to all Wi-Fi standards
– Wireless network cards, configuration software,
capability to run in multiple network styles
– How transmissions work
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Hardware
• Wireless Ethernet NICs
– Same function as wired, except transmission uses
radio waves
• Networking capabilities are built into many
modern devices
– Can add an expansion card to desktop computers
• USB NICs are placeable
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.1 Wireless PCIe NIC
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.2 External USB wireless NIC
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Access Point (WAP)
• Interconnects wireless network nodes with
wired networks
• A basic WAP operates like a hub at Layer 1
• Often multiple devices combined in one box
– Built-in switch and/or router
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.3 Linksys device that acts as wireless
access point, switch, and DSL router
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Software
• Wireless device drivers
– Consult your vendor’s instructions
• Wireless configuration utility settings
– Link state
– Signal strength
– Wireless network modes
– Security encryption
– Power-saving options
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.4 Wireless client configuration utility
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Network Modes
• Ad hoc mode
– Also called peer-to-peer mode
– Uses a mesh topology
– Works well for small groups of computers or
temporary networks
• Independent Basic Service Set (IBBS)
– Two or more wireless nodes communicating in ad
hoc form
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.5 Wireless ad hoc mode network
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Network Modes (cont’d.)
• Infrastructure mode
– Uses one or more WAPs to connect the wireless
network nodes centrally
– Similar to a wired star topology
• Basic service set (BSS)
– Serviced by a single WAP
• Extended service set (ESS)
– Serviced by two or more WAPs
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.6 Wireless infrastructure mode network
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Range
• Wireless networking range is hard to define
– Greatly affected by environmental factors
• Qualifiers such as around 150 feet and about
300 feet
• Actual range is about half of manufacturer’s
listed maximum range
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Basic Service Set Identifier (BSSID)
• The most basic infrastructure mode network
• A BSS of one WAP and one or more wireless
clients
• The BSSID is the same as the MAC address of
the WAP
• IBSS nodes (ad hoc mode) generate a 48-bit
string as the BSSID
– BSSID is added in every frame
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Service Set Identifier (SSID)
•
•
•
•
Another level of naming
Standard name applied to the BSS or IBSS
Sometimes called a network name
32-bit identification string
– In the header of each frame processed by a WAP
• Every Wi-Fi device must share the same SSID
to communicate in a network
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Extended Service Set Identifier (ESSID)
• A Wi-Fi network with multiple WAPs (ESS)
• Each WAP is connected to a central switch or
switches to become part of a single broadcast
domain
• Clients connect to whichever WAP has the
strongest signal
– Roaming: process of changing WAP connections
• Most Wi-Fi devices use the term SSID
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Broadcasting Frequency
• Potential for interference from other wireless
devices
– Wireless devices must operate in specific
broadcasting frequencies
– A tech must know frequencies of other wireless
devices in troubleshooting interference issues
• Original 802.11 standards use 2.4-GHz or 5.0GHz frequencies
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Broadcasting Methods
• Original IEEE 802.11 standard used spreadspectrum radio waves
– Broadcasts data in small, discrete chunks
– Uses different frequencies within a range
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Spread-Spectrum Broadcasting
Methods
• Direct-sequence spread-spectrum (DSSS)
• Frequency-hopping spread-spectrum (FHSS)
• Orthogonal frequency-division multiplexing
(OFDM).
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Direct-Sequence Spread-Spectrum
(DSSS)
•
•
•
•
Sends simultaneously on different frequencies
Used by early 802.11 standards
Uses about 22 MHz of bandwidth
Capable of greater data throughput than
OFDM
• More prone to interference than FHSS
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Frequency-Hopping Spread-Spectrum
(FHSS)
• Constantly shifts (hops) from frequency to
frequency
• Sends on one frequency at a time
• Uses less bandwidth than DSSS (~1MHz)
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Orthogonal Frequency-Division
Multiplexing (OFDM)
• Latest method
• Combines multiple frequencies of DSSS
with FHSS’s hopping capability
• Used on all but the earliest 802.11 networks
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Channels
• A channel is a portion of the spectrum
• 802.11 standard defined 14 channels of
20MHz each
– Different countries may limit channels
– In the U.S., WAP may use channels 1 through 11
• Do not use adjacent channels on nearby WAPs
• Most WAPs use channels 1, 6, or 11
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Channels (cont’d.)
• The 5.0-GHz band offers many more channels
than the 2.4-GHz band
• There are 40 different channels in the
spectrum
• 802.11 versions that use the 5.0-GHz band use
automatic channel switching
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Carrier Sense Multiple Access/Collision
Avoidance (CSMA/CA)
• Wireless devices cannot detect collisions
– Cannot listen and send at the same time
– If two clients were to collide, there is no simpleto-detect electrical peak
• Two collision avoidance methods
– Distributed Coordination Function (DCF)
– Point Coordination Function (PCF)
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
DCF and PCF
• Only DCF is implemented
• DCF specifies rules for sending data onto the
network media
– Defines a backoff period in addition to the normal
interframe gap (IFG) wait period
– Requires an ACK from receiving nodes
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
802.11b
•
•
•
•
Data throughput up to 11 Mbps
Range up to 300 feet
Popular
Uses the crowded 2.4-GHz frequency
– More likely to have interference from other
wireless devices
– Signal interference can increase latency
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
802.11a
• Devices on market after 802.11b
• Different from all other 802.11 standards
– 5-GHz frequency range
– Speeds up to 54 Mbps
– Short range: about 150 feet
– Never as popular as 802.11b
– Incompatible with 802.11b
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
802.11g
•
•
•
•
•
•
Up to 54 Mbps
Range of 802.11b: about 300 feet
Backward compatible with 802.11b
WAP can service both 802.11b and 802.11g
All 802.11g network runs in native mode
Runs in mixed mode if 802.11b devices added
– Communications drop to 11 Mbps max
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
802.11n
•
•
•
•
•
•
•
Faster and newer antenna technology
Most devices must use multiple antennas
Multiple in/multiple out (MIMO)
Up to 600 Mbps theoretically
Many WAPs employ transmit beamforming
Dual-band WAPs run at 2.4- and 5.0 GHz
WAPs support 802.11b/g/n devices
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
802.11ac
•
•
•
•
•
•
Expansion of the 802.11n standard
Incorporates additional streams
Wider bandwidth
Better speed
Only operates in the 5.0 GHz band
Multiuser Mimo (MU-MIMO)
– Can broadcast to multiple users simultaneously
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wi-Fi Protected Setup (WPS)
• A special standard created by the wireless
industry to makes configuration easier
• Works in two modes
– Push button
– PIN method
• Easy to use
• Susceptible to various WPS attacks
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wi-Fi Security
• Problem
– Easy-to-install devices have no default security
– Network data frames are in radio waves
• Three wireless security methods
– MAC address filtering
– Authentication
– Data encryption
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
MAC Address Filtering
• Limits access to specific NICs
• Lists MAC addresses for accepted users
– The list is stored in a table in the WAP
•
•
•
•
Rejects frames with other MAC addresses
Alternatively create an exclusion list
Not scalable on a modern network
Problem: hackers can spoof MAC addresses
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Authentication
•
•
•
•
Users with proper credentials get access
Can use a centralized security database
Requires extra steps for wireless users
802.1X standard
– RADIUS server
– Extensible Authentication Protocol (EAP)
password encryption
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Authentication (cont’d.)
• RADIUS server
– Provides authentication for network access
– Enables access to user’s rights on the network
– Client wireless computer is called a supplicant
– WAP is the Network Access Server (NAS)
– NAS contacts the RADIUS server
– RADIUS server checks the security database
– User is given access if credentials are correct
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.7 Authenticating using RADIUS
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wireless Authentication
Problem Areas
• Connection between devices must be secure
– PPP between supplicant and WAP/NAS
– IPsec between NAS and RADIUS server
– RADIUS server uses an authentication protocol
(EAP)
– WAP and wireless NICs must use the same
authentication scheme
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.8 Authentication using RADIUS with protocols in place
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.9 Setting EAP authentication scheme
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Data Encryption
• Encryption electronically scrambles data
packets
– The receiving network device requires the
encryption key to unscramble the packet
• WPA2 provides a good level of security to data
packets in transit
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Data Encryption Using WEP
• Wired Equivalent Privacy (WEP)
– 64- or 128-bit encryption algorithm called RC4
– Uses an initialization vector (IV) of 24 bits
• Issues with WEP
– IV length uses 24 of the 64 (or 128) bits
– Encryption key is static and shared
– No user authentication
– Outdated and easily cracked
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wi-Fi Protected Access (WPA)
• Dynamic encryption key generation
– Issued per user and per session
• Temporal Key Integrity Protocol (TKIP)
• 128-bit encryption key
• Problem: key can be broken
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Wi-Fi Protected Access 2 (WPA2)
• Uses Advanced Encryption Standard (AES)
– 128-bit block cipher
– Not completely hack proof
– Difficult enough to deter casual hackers
• Adding a RADIUS server for authentication
enables WPA2-Enterprise
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Enterprise Wireless
• Enterprise devices differ from SOHO devices
– Robust construction
– Centralized management
– VLAN pooling
– Power over Ethernet
– Bringing personal wireless devices into the
enterprise environment
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Robust Device Construction
• Enterprise WAP is made of better materials
• More configurable
• Can swap out antennas and radios making it
possible to upgrade to the latest technologies
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.10 Cisco Enterprise WAP
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Enterprise Wireless Administration
• Large number of WAPs
– Offload configuration job to a wireless controller
– Switch designed to handle multiple WAPs
• Thick client: configurable via its own interface
• Thin clients: configurable by a wireless
controller
• Standard protocol: Lightweight Access Point
Protocol (LWAPP)
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.11 Configuring WAPs
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.12 Wireless Controller
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
VLAN Pooling
• A large number of clients may be on a single
SSID at a given moment
• Traditional solution
– Divide the WLAN into multiple broadcast domains
– Use routers to interconnect the domains
• VLAN pooling
– Create a pool of VLANs for a single SSID
– Randomly assign wireless clients to one VLAN
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Power over Ethernet (PoE)
• Power and Ethernet signals via Ethernet
cables
• Good for WAPs far from power outlets
• The WAP and the switches must support PoE
• 2003: original PoE standard 802.3af
– Supported a maximum 15.4 watts of DC power
– Revised in 2009 to support 25.5 watts
– New amendment called 802.3at or PoE+
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Bring Your Own Device
• Integrating personal mobile devices into a
corporate network
• Network administrators can allow or deny
mobile devices access to network resources
– On- and off-boarding mobile devices
• Mobile device management solutions
– Provide robust security without compromising
connectivity
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
WLAN vs. PAN
• Wireless LAN (WLAN)
– Always an 802.11-based network and able to
serve multiple clients
• Personal Area Networks (PAN)
– Point-to-point over short distances
– Examples: Bluetooth, infrared, and NFC
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Implementing Wi-Fi
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Steps for Installing a Wireless Network
• Perform a site survey
• Install one or more access points
• Configure the access point(s) and wireless
clients
• Test the network to verify that it works as
intended
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Performing a Site Survey
• Reveals obstacles and determine best
locations for access points
• Main components for crating a site survey
– Floor plan of the area
– Wireless survey tools
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Performing a Site Survey
• What wireless is already there?
– Discover wireless networks in the same area
– Today’s challenge is the preexistence of high
device density environments
– Tools are available to assist with the survey
• Interference sources
– Create a sketch of potential interference sources
– Plan the network to eliminate dead zones
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.13 AirMagnet Survey Pro
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.14 Acrylic Wi-Fi
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.15 Site survey with heat map
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.16 Site survey with interference sources noted
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Installing the Client
• Install Wi-Fi hardware and software
• PCIe NIC
– Install the NIC onto a free slot on the
motherboard
– May need to attach the antenna
• USB NIC
– Install drivers and software before you connect
the NIC to the computer
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.17 Wi-Fi NIC installed
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Setting Up an Ad Hoc Network
• Set NICs for ad hoc mode
• SSID
– Each wireless node must use the same network
name
• IP addresses
– No two nodes can use the same IP address
• Ensure the File and Printer Sharing service is
running on all nodes
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.18 Selecting ad hoc mode in a
wireless configuration utility
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Setting Up an Infrastructure Network
• Determine the optimal location for the WAP
• Configure the WAP
• Configure any clients to access the WAP
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Placing the Access Points/Antennas
• Omnidirectional antenna
– Radiates outward from the WAP in all directions
– Antenna is place the in the center of the area
– Standard straight-wire dipole antennas are used
• Omnidirectional and centered does not work
for every network
• The gain from a typical WAP is 2 dB
– Increase gain with one or more bigger antennas
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.19 WRT54G showing two antennas
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.20 Room layout with WAP in the center
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.23 Dipole radiation pattern
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.24 Replacement antenna on a WAP
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Placing the Access Points/Antennas
(cont’d.)
• A unidirectional antenna focuses a radio wave
into a beam
– Various types: parabolic, dish, and Yagi
• Patch antennas work well for a strong signal
within a room
• Optimal placement depends on space needs
and security concerns
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Configuring the Access Point
•
•
•
•
•
•
Log in to the browser-based setup utility
Configure the SSID (ESSID) and beacon
Configure MAC address filtering
Configure encryption
Configure channel and frequency
Configure the client
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.27 Security login for Linksys WAP
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.28 Linksys WAP setup screen
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.29 Setting the beacon interval
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.30 MAC address filtering
configuration screen for a Linksys WAP
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.31 Encryption key configuration screen on
Linksys WAP
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.32 Encryption screen on client wireless
network adapter configuration utility
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.33 Encryption screen with RADIUS option
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.34 Changing the channel
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.35 Selecting frequency
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.36 Typing in an SSID manually
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Extending the Network
• Add a WAP to create an Extended Service Set
• Install a wireless bridge
– Connect two wireless networks; or join a wireless
and a wired network together
– Types of wireless bridges: point-to-point and
point-to-multipoint
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.37 Linksys wireless bridge device
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Verify the Installation
• Move traffic between computers using the
wireless connection
• Always verify installation before leaving
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Troubleshooting Wi-Fi
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Logical Troubleshooting Steps
• Three types of symptoms
– Cannot get on the wireless network
– Wireless connections are way too slow
– Wireless connection is doing weird things
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
No Connection
• Channel problems
– Overlapping channels
– Mismatched channels
• Wrong encryption
– Entered the wrong encryption key
– Symptoms: not on network, continual prompting
for password, APIPA address
– Solution: enter the correct password
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
No Connection (cont’d.)
• Signal/power issues
– Symptoms: signal loss, not able to connect
– Solutions:
• Move closer to the WAP and avoid dead spots
• Turn up the power
• Replace the omnidirectional antenna with a
unidirectional antenna
• Upgrade to newer 802.11n or 802.11ac
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.38 Increasing power on a Cisco WAP
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Slow Wireless Connections
• Clear connection to an SSID
• Good IP address
• Potential causes of slowness
– Too many devices overworking WAPs
– Too much RF interference on the network
– Insufficient RAM
– Malware
– Other non-wireless specific issues
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Overworked WAPs
• Device saturation
– Too many devices attaching to a single SSID over
time
• Bandwidth saturation
• Bounce
• Solutions: add extra WAPs, upgrade hardware
to 802.11ac
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Interference
• Sources of radio frequency interference (RFI)
– Non-Wi-Fi sources including lighting, Bluetooth,
wireless phones, and microwaves
– Wi-Fi networks
• Solution: abandon the 2.4-GHz channel
• Scan for RF sources using some type of RF
scanner/analyzer
Copyright © 2015 by McGraw-Hill Education. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Figure 15.39 SNR on AirMagnet
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Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Fourth Edition (Exam N10-006)
Weird Connection
•
•
•
•
Open (non-encrypted) 802.11 networks
Wrong SSID
Untested updates/incompatibilities
Rogue access point (rogue AP): an
unauthorized access point
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