Implementing Wireless and WLAN
Chapter 19
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Chapter Objectives
Describe standards associated with wireless media
Identify and describe the purpose of the components in a small wireless network
Identify common issues with implementing wireless networks
At the end of this Chapter you will be
able to:
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Introduction to Wireless Technology Transmitting a signal using the typical 802.11 specifications works
a lot like it does with a basic Ethernet hub: They’re both two-way forms of communication, and they both use the same frequency to both transmit and receive, often referred to as half-duplex. Wireless LANs (WLANs) use radio frequencies (RFs) that are radiated into the air from an antenna that creates radio waves
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The 802.11 StandardsCommittee Purpose
IEEE 802.11a 54Mbps, 5GHz standardIEEE 802.11b Enhancements to 802.11 to support 5.5 and
11MbpsIEEE 802.11c Bridge operation procedures; included in the
IEEE 802.1D standardIEEE 802.11d International roaming extensionsIEEE 802.11e Quality of serviceIEEE 802.11F Inter-Access Point ProtocolIEEE 802.11g 54Mbps, 2.4GHz standard (backward
compatible with 802.11b)IEEE 802.11h Dynamic Frequency Selection (DFS) and
Transmit Power Control (TPC) at 5GhzIEEE 802.11i Enhanced securityIEEE 802.11j Extensions for Japan and U.S. public safetyIEEE 802.11k Radio resource measurement enhancements
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Conti... IEEE 802.11m Maintenance of the standard; odds and ends
IEEE 802.11n Higher throughput improvements using MIMO (multiple input, multiple output antennas)
IEEE 802.11p Wireless Access for the Vehicular Environment (WAVE)
IEEE 802.11r Fast roaming
IEEE 802.11s Extended Service Set (ESS) Mesh Networking
IEEE 802.11T Wireless Performance Prediction (WPP)
IEEE 802.11u Internetworking with non-802 networks (cellular, for example)
IEEE 802.11v Wireless network management
IEEE 802.11w Protected management frames
IEEE 802.11y 3650–3700 operation in the U.S
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Comparing 802.11
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Wireless Topologies Wireless topologies are:
Ad-hoc Topology
Infrastructure Topology
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Ad-hoc Topology
Ad hoc wireless networks technically use an Independent Basic Service Set (IBSS) topology.
This means that each wireless device independently manages the wireless network. This type of wireless network originates from and includes the wireless device, as shown in Figure.
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Infrastructure Topology involves using a dedicated piece of equipment (typically a wireless
access point) to initiate and manage the wireless network.
Wireless access points can be configured to use one of two infrastructure modes: Basic Service Set (BSS) or Extended Service Set (ESS). The BSS is the simplest form of wireless network. It includes a single wireless access point managing a group of clients, as shown in Figure.
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Single basic service set designpowered by DJ 11
An extended service set designpowered by DJ 12
Wireless Security Wireless Security – A Brief Overview
Points:- SSIDs, WEP, and MAC Address Authentication
SSID is a common network name for the devices in a WLAN system that creates the wireless LAN. An SSID prevents access by any client device that doesn’t have the SSID.
Two types of authentication were specified by the IEEE 802.11 committee: open and shared-key authentication. Open authentication involves little more than supplying the correct SSID—but it’s the most common method in use today.
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Conti.. With shared-key authentication, the access point sends the client
device a challenge-text packet that the client must then encrypt with the correct Wired Equivalency Protocol (WEP) key and return to the access point. Without the correct key, authentication will fail and the client won’t be allowed to associate with the access point
MAC addresses can be statically typed into each access point, and any of them that show up without that MAC addresses in the filter table would be denied access.
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WPA or WPA 2 Pre-Shared Key WPA or WPA2 Pre-Shared Key (PSK) is a better form of wireless
security than any other basic wireless security method mentioned so far.
Wi-Fi Protected Access (WPA) is a standard developed in 2003 by the Wi-Fi Alliance, formerly known as WECA. WPA provides a standard for authentication and encryption of WLANs that’s intended to solve known security problems existing up to and including the year 2003.
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Configuring Our Wireless Internetwork
Interface and Connectionspowered by DJ 16
Conti..
Edit Interface Connectionpowered by DJ 17
Conti..
Wireless Express Setuppowered by DJ 18
Conti..
SSID Configurationpowered by DJ 19
Conti..
Network Interface Radio Settingspowered by DJ 20
Conti..
Wireless Setting Configurationpowered by DJ 21
Conti..
Security Summarypowered by DJ 22
Conti..
Express Setup Screenpowered by DJ 23
Wireless TroubleshootingClient Troubleshooting
Most wireless issues are related to the client:
Verify that the wireless card is enabled: Most new laptops have a button or switch that disables the wireless card to save battery life.
Move to a “known good” region of the building: Do your testing in an area known to have a strong wireless signal. This may require using multiple wireless devices.
Verify that the client can identify the wireless network using the installed wireless utility: If you are unable to identify wireless SSID(s) in your vicinity, the client’s wireless card may be disabled, or the wireless access point may not be working.
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Conti.. Ensure that the wireless client has the correct wireless security
information and supports your security standards: You may need to re-enter the pre shared key to ensure that you entered it correctly. Likewise, the wireless card may not support the wireless security on your network. Try connecting to an SSID that does not use security from the wireless device.
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Wireless Access Point Troubleshooting
Most troubleshooting that deals with the wireless access point focuses on physical considerations:
Verify that the wireless access point is running the latest firmware version: Nothing is worse than spending hours on a problem that is related to a bug in the wireless firmware.
Test the wireless reception radius at different times of the day: Because of the varying degrees of interference that may occur over time, it is best to run multiple tests on your signal strength. You can do this simply and inexpensively by carrying around a laptop and observing the reception at differing locations.
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Conti.. Verify your wireless channel configuration: If you have multiple
wireless access points or are in an area where other access points may interfere, verify (using wireless software) the most saturated and unsaturated channels. For 802.11b/g, use channels 1, 6, or 11 in the U.S. For 802.11a, many more channels are available, and you should test for the cleanest frequency.
Consider the materials around and close to the access point: Try to avoid installing the access point near metal objects, which reflect the signal. Realize that a concrete block wall will absorb much more signal than a drywall barrier.
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THANK YOU
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