Transcript Slide 1

Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Wireless Networking
Chapter 15
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Objectives
• Explain wireless networking standards
• Describe the process for implementing
Wi-Fi networks
• Describe troubleshooting techniques
for wireless networks
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Overview
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Introduction to wireless
networking
• Wireless network uses radio frequency (RF)
waves as the media
–
–
–
–
–
Convenient and sometimes the only option
Same OSI layers as wired networks
Same upper-layer protocols as wired networks
Different methods for accessing the media
Wi-Fi IEEE 802.11 wireless Ethernet standards
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Three parts to Chapter 15
• Wi-Fi standards
• Implementing Wi-Fi
• Troubleshooting Wi-Fi
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Wi-Fi standards
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Wi-Fi IEEE 802.11 standards
– 802.11a
– 802.11b
– 802.11g
– 802.11n
• Certified by 300-member Wi-Fi Alliance
– Members design and manufacture
Wi-Fi products
– Certification should ensure compatibility
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• 802.11
– Standards define how devices communicate
– Some define how to secure communications
– Each sub-standard by a IEEE subcommittee
– Wireless Fidelity (Wi-Fi)
– 802.11 established baseline features
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Hardware
– Adapters
• Wireless Ethernet NICS
• PCI, PC Card, external USB
– Wireless access point (WAP)
• Basic WAP operates like a hub at Layer 1
• Often multiple devices in one box
– High-speed hub or switch
– Bridge
– Router
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.1 Wireless PCIe NIC
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.2 External USB wireless NIC
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.3 Linksys device that acts as wireless
access point, switch, and DSL router
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Software
– Wireless device drivers
– Wireless configuration utilities
– Link state
– Signal strength
– Other settings
• Wireless network modes
• Security
• Power-saving options
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.4 Wireless client configuration utility
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Wireless network modes
– Ad hoc mode
• Also called peer-to-peer mode
• Uses a mesh topology
• Independent Basic Service Set (IBBS)
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.5 Wireless ad hoc mode network
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Wireless network modes (cont.)
– Infrastructure mode
• Uses one or more access points
• 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
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.6 Wireless infrastructure mode network
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Range
– Hard to define
– 802.11 “around 150 feet”
– Affected by environmental factors
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Basic Service Set Identifier (BSSID)
– Most basic infrastructure mode network
– BSS is one WAP and one or more nodes
– BSSID same as the MAC address of WAP
– IBSS nodes (ad hoc mode) 48-bit string
– BSSID in every frame
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Service Set Identifier (SSID)
– Another level of naming
– Standard name applied to BSS or IBSS
– Sometimes called a network name
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Extended Service Set Identifier (ESSID)
– Wi-Fi network with multiple WAPs (ESS)
– Most Wi-Fi devices use term SSID
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Broadcasting frequency
– Potential for interference from other
wireless devices
– Tech must know frequencies of other
wireless devices
– Original 802.11 standards use 2.4-GHz
frequency band
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Broadcast methods
– Original IEEE 802.11 standard used spreadspectrum radio waves
• Broadcasts data in small, discrete chunks
• Used different frequencies within a range
• Three different spread-spectrum broadcasting
methods
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Direct-sequence spread-spectrum (DSSS)
– Sends simultaneously on different
frequencies
– Early 802.11 standards used this
– Uses ~22 MHz of bandwidth
– Capable of greater data throughput
than OFDM
– More prone to interference than FHSS
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Frequency-hopping spread-spectrum
(FHSS)
– Hops from frequency to frequency
– Sends on one frequency at a time
– Uses less bandwidth than DSS (~1MHz)
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Orthogonal frequency-division
multiplexing (OFDM)
– Latest method
– Combines multiple frequencies of DSSS
with FHSS’s hopping capability
– Later 802.11 standards use this
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Channels
– A portion of the spectrum
– 802.11 standard defined 14 channels
– Different countries may limit channels
– In the U.S., WAP may use channels 1 – 11
– There is overlap
– Do not use close channels on nearby WAPs
– Most WAPs default to channel 1, 6, or 11
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• CSMA/CA
– Carrier sense multiple access/collision
avoidance
– Access method
• Allows multiple devices to share network media
– Wireless devices cannot detect collisions
– Two collision avoidance methods
• Distributed Coordination Function (DCF)
• Point Coordination Function (PCF)
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• 802.11b
– Data throughput up to 11 Mbps
– Range up to 300 feet
– Popular
• 2.4-GHz frequency is crowded
• More likely to have interference from other
wireless devices
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• 802.11a
– Devices on market after 802.11b
– Different from all other 802.11 standards
• 5-GHz frequency range
• Up to 54 Mbps
• Short range (~150 feet)
• Never as popular as 802.11b
• Incompatible with 802.11b
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Table 15.1
802.11 Summary
Standard Frequency Spectrum
802.11
Table 15.2
2.4GHz
DSSS
Table 15.3
2.4GHz
DSSS
~300′ 802.11
Speed
Range Compatibility
11 Mbps ~300′ 802.11b
802.11a Summary
Standard Frequency Spectrum
802.11a
2 Mbps
Range Compatibility
802.11b Summary
Standard Frequency Spectrum
802.11b
Speed
5.0GHz
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
DSSS
Speed
Range Compatibility
54 Mbps ~150′ 802.11a
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• 802.11g
– Up to 54 Mbps
– Range of 802.11b (~300 feet)
– Backward compatible with 802.11b
– WAP can service both 802.11b and 802.11g
– All 802.11g network runs in native mode
– Add 802.11b devices
• Mixed mode
• All communications drop to 11 Mbps max
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• 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 use transmit beamforming
– Dual-band WAPs run at 5 GHz and 2.4 GHz
– Some WAPs support 802.11a devices
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Table 15.4
802.11g Summary
Standard Frequency Spectrum Speed
802.11g 2.4GHz
Table 15.5
OFDM
Range Compatibility
54 Mbps ~300′ 802.11b/g
802.11n Summary
Standard Frequency Spectrum
802.11n 2.4GHz1
OFDM
Speed
Range Compatibility
100+Mbps ~300′ 802.11b/g/n2
1 Dual-band 802.11n devices can function simultaneously at both 2.4- and 5.0-GHz bands.
2 Many dual-band 802.11n WAPs support 802.11a devices as well as 802.11b/g/n devices. This is not part of
the standard, but something manufacturers have implemented.
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Wireless networking security
– Problem
• Easy-to-install devices have no default security
• Network data frames are in radio waves
– Three wireless security methods
• MAC address filtering
• Wireless authentication
• Data encryption
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• MAC address filtering
– Limits access to specific NICs
– “Accepted users” list of MAC addresses
– List stored in WAP
– Rejects frames with other MAC addresses
– Alternatively create exclusion list
– Problem: hackers can spoof MAC addresses
– MAC address must be updated for changes
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• 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
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Wireless authentication (cont.)
– RADIUS server
• Provides authentication for network access
• Enables access to user’s rights on network
• Client computer is called a supplicant
• WAP is the Network Access Server (NAS)
• NAS contacts RADIUS server
• RADIUS server checks security database
• User given access if credentials are correct
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.7 Authenticating using RADIUS
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Wireless authentication problem areas
– Connection must be secure
• PPP between supplicant and WAP/NAS
• IPsec between WAP/NAS and RADIUS server
• RADIUS server uses an authentication protocol
– EAP-TLS
– EAP-TTLS
– PEAP
• WAP and wireless NICs must use same
authentication protocol
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.8 Authentication using RADIUS with
protocols in place
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.9 Setting EAP authentication scheme
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Data encryption
– Wired Equivalent Privacy (WEP)
• 64- or 128-bit encryption algorithm (24-bit IV)
• Problems
– Easily cracked
– Size of key is a weakness (40- & 104-bit keys)
– Weak implementation of RC4 protocol
– Key is static and shared between all devices
– No user authentication – only nodes by MAC
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Data encryption (cont.)
– 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
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Data encryption (cont.)
– Wi-Fi Protected Access 2 (WPA2)
• Amendment of 802.11 standard by 802.11i
– Issued per user and per session
• Uses Advanced Encryption Standard (AES)
– 128-bit block cipher
– Not completely hack proof
– Deters casual hackers
• Adding a RADIUS server for authentication enables
WPA2-Enterprise (vs. WPA2-PSK in SOHO networks)
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Power over Ethernet (PoE)
– Power and Ethernet signals via Ethernet
ports
– Good for WAPs far from power outlets
– Both WAP and switch must comply
with PoE
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Implementing Wi-Fi
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Performing a site survey
– What wireless devices are already there?
• Radio bands in use
• Existing SSIDs and channels
• Unique SSIDs
• Separate channels within same radio band
– Locate interference sources
• Create sketch and identify interference sources
• High-interference area may require 802.11n
• May need multiple WAPs to avoid dead zones
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.10 Site survey with interference sources
noted
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Installing the client
– Read instructions with NIC
• Install bus NIC and attach antenna
• Special instructions for USB NIC
– Install drivers and software first
– Then connect NIC
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.11 Wi-Fi NIC installed
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Setting up an ad hoc network
– Set NICs for ad hoc mode
– SSID
– IP addresses
– Channel
– Sharing
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.12 Selecting ad hoc mode in wireless
configuration utility
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Setting up an infrastructure network
– Placing the access point
• Omnidirectional and centered
– Radio waves flow outward
– Standard straight-wire dipole antennas
• Off-center position
• Gaining gain
• Focusing the wave with directional antenna
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.13 Room layout with WAP in the center
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.14 Replacement antenna on a WAP
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Setting up an infrastructure network
(cont.)
– Access point configuration
• Configure the SSID (ESSID) and beacon
• Configure MAC address filtering
• Configure encryption
• Configure channel and frequency
• Configure the client
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.15 Security login for Linksys WAP
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.16 Linksys WAP setup screen
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.17 Setting the beacon interval
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.18 MAC address filtering configuration
screen for a Linksys WAP
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.19 Encryption key configuration screen on
Linksys WAP
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.20 Encryption screen on client wireless
network adapter configuration utility
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.21 Encryption screen with RADIUS option
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.22 Changing the channel
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.23 Selecting frequency
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.24 Typing in an SSID manually
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Extending the network
– Adding a WAP
– Wireless bridges
• Point-to-point
• Point-to-multipoint
– Repeating bridges
– Bridges with access point and router
functions
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Verify the installation
– Move traffic between computers
– Always verify installation before leaving
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.25 Linksys wireless bridge device
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Troubleshooting Wi-Fi
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Logical troubleshooting steps
– What is the scope of the wireless problem?
• Who is affected
– One wireless client?
– All wireless clients?
• What is the nature of the problem?
– Which network services do/don’t work?
– If some work, but others don’t, it is not a network
problem
• When did problem start?
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Hardware troubleshooting
– Like PC troubleshooting
– Detect driver or resource problems with
Device Manager
• If necessary, reinstall the device driver
• If necessary, reset the IRQ resources
• Device not present?
– Check connection on USB
– Restart PC/Laptop to enable detection
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Software troubleshooting
– Wireless adapter configuration
• User vendor’s driver and configuration utility
• Use Device Manager to uninstall and install
vendor driver and utility
– WAP’s firmware version
• Symptom: client connects, but slow speed
• Update access point’s firmware
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Connectivity troubleshooting
– Not connecting automatically and quickly
– Causes
• Incorrect configuration
• Low signal strength or Interference
• Multipath (signal bouncing) causing multipath
null spot
• Overlapping WAP signals when not broadcasting
SSID ( causes SSID mismatch errors)
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Connectivity troubleshooting (cont.)
– Solutions
• Higher-gain antennas
• Move PC or WAP
• Put WAPs on different channels
• Move the interference
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
Figure 15.26 Windows XP Professional’s wireless
configuration utility
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.
Mike Meyers’ CompTIA Network+® Guide to Managing and
Troubleshooting Networks, Third Edition (Exam N10-005)
• Configuration troubleshooting
– Check SSID
• Must be identical on all devices
– Check MAC address filter list for new NICs
– Check security configuration
• All wireless nodes and WAPs must match
• Check for mistyped encryption key
© 2012 The McGraw-Hill Companies, Inc. All rights reserved.