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  • Implementing Wireless and WLANChapter 19powered by DJ*

    powered by DJ

  • Chapter ObjectivesDescribe standards associated with wireless media Identify and describe the purpose of the components in a small wireless networkIdentify common issues with implementing wireless networks

    At the end of this Chapter you will be able to:powered by DJ*

    powered by DJ

  • Introduction to Wireless TechnologyTransmitting a signal using the typical 802.11 specifications works a lot like it does with a basic Ethernet hub: Theyre 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 wavespowered by DJ*

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  • The 802.11 StandardsCommittee PurposeIEEE 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 802.11mMaintenance of the standard; odds and endsIEEE 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 roamingIEEE 802.11s Extended Service Set (ESS) Mesh NetworkingIEEE 802.11T Wireless Performance Prediction (WPP)IEEE 802.11u Internetworking with non-802 networks (cellular, for example)IEEE 802.11v Wireless network managementIEEE 802.11w Protected management framesIEEE 802.11y 36503700 operation in the U.S

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  • Comparing 802.11

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  • Wireless TopologiesWireless topologies are:Ad-hoc TopologyInfrastructure 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 Topologyinvolves 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*

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  • An extended service set designpowered by DJ*

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  • Wireless SecurityWireless Security A Brief OverviewPoints:- SSIDs, WEP, and MAC Address AuthenticationSSID 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 doesnt 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 SSIDbut its 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 wont be allowed to associate with the access pointMAC 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 KeyWPA 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 thats intended to solve known security problems existing up to and including the year 2003.powered by DJ*

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  • Configuring Our Wireless InternetworkInterface and Connectionspowered by DJ*

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  • Conti..Edit Interface Connectionpowered by DJ*

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  • Conti..Wireless Express Setuppowered by DJ*

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  • Conti..SSID Configurationpowered by DJ*

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  • Conti..Network Interface Radio Settingspowered by DJ*

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  • Conti..Wireless Setting Configurationpowered by DJ*

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  • Conti..Security Summarypowered by DJ*

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  • Conti..Express Setup Screenpowered by DJ*

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  • Wireless TroubleshootingClient TroubleshootingMost 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 clients 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.powered by DJ*

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  • THANK YOUpowered by DJ*

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