Cabletron Systems 3Com manual Overview of Digital Wireless Networking

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22CHAPTER 1: OVERVIEW OF DIGITAL WIRELESS NETWORKING

and the addition of the AP to the AP table with a proximity classification. An unsuccessful AP packet transmission generates another wireless client probe on the same channel. If the wireless client fails to receive a probe response within the time limits, it repeats the probe process on the next channel in the sequence. This process continues through all channels in the range.

A wireless client can roam within the coverage area by switching APs. Roaming is transparent and virtually instantaneous in high-level applications. Roaming occurs when:

■An unassociated wireless client attempts to associate or reassociate with an available AP.

■The supported rate changes or the wireless client finds a better transmit rate with another AP.

■The signal quality of a potential AP exceeds that of the current AP.

■The ratio of good-transmitted packets to attempted-transmitted packets falls below a threshold.

■The wireless client detects an imbalance in the number of wireless clients associated with available APs and roams to a less loaded AP.

A wireless client selects the best available AP and adjusts itself to the AP direct-sequence channel to begin association. Once associated, the AP begins forwarding any frames it receives addressed to the wireless client. Each frame contains fields for the current direct-sequence channel. The wireless client uses these fields to resynchronize to the AP.

Roaming The AirConnect Roaming feature enables a wireless client on the Internet to move from one AP to another within a single subnet. The scanning and associating process continues for active wireless clients. This allows the wireless clients to find new APs and discard out-of-range or deactivated APs. By testing the airwaves, the wireless clients can choose the best network connection available.

Extended Roaming The AirConnect extended roaming (roaming across routers) feature enables a wireless client on the Internet to move from one subnet to another while keeping its IP address unchanged. extended roaming enables a wireless client to communicate with other hosts using only its home IP address after changing its point-of-attachment to the Internet/Intranet.

For extended roaming to work, you must use a static IP address.

The Internet Protocol identifies the wireless client point of attachment to a network through its IP address. The AP routes packets according to the location information contained in the IP header. If the wireless client roams across routers to another subnet with extended roaming disabled, the following situations occur:

■The wireless client changes its point of attachment without changing its IP address, causing forthcoming packets to become undeliverable.

■The wireless client changes its IP address when it moves to a new network, causing it to lose connection.

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Contents AirConnect 11 Mbps Wireless LAN Access Point User Guide VersionClara, California 3Com CorporationBayfront Plaza Santa 95052-8145Contents Installing Access Point Hardware Monitoring Wireless Clients Access Point Installation Configuring the AP Access Point Specifications Technical Support Page AirConnect Network Overview of Digital Wireless NetworkingIntroduction TopologiesOverview of Digital Wireless Networking AirConnect Network Topologies Point AirConnect AccessWireless clients To the Ethernet LANAirConnect Access Point Radio Basics PowerBASE-TWireless clients and APs Results in the original digital dataRadio Basics Wireless LAN Service Area 802.1d Spanning Tree SupportSite Surveys Filtering and Access Control Network Control Protocol NCP as described PPP Connection Data Rate Requirement Overview of Digital Wireless Networking Theory of Operation Simple Network Management Protocol Snmp Management protocol MIB Using SnmpProgrammable Snmp Trap Support Increased MIB SupportUsing the User Interface Method DescriptionPackage Contents Installing Access Point HardwarePrecautions RequirementsRemote power distribution system, Part Number AP-PS-11 Power OptionsStandard power supply 115/230VAC, 50/60Hz, 24V/14 US line cord Part NumberBelow Mounting the APWall Mount To mount an AP on a wall Ceiling Mount To mount an AP on a ceiling Mounting the AP PowerBASE-T UsingPowerBASE-T can be used to power the AP Off Blinking Power No power Power on During boot sequence LED IndicatorsCondition, and other activity Verify AP Operation Troubleshooting3Com Support Center Electrical Management System EMS operating outletVerify Network Wiring Topology Network connection verificationPage Interface Statistics Monitoring StatisticsSystem Properties Forwarding CountsRadio Frequency Ethernet StatisticsStatistics Press Esc or Previous F4 to exit MiscellaneousStatistics window, select Main Menu→Misc Statistics Type Name DefinitionKnown APs Clearing StatisticsSelect Clear All Statistics Help File Access Gaining Access to the User Interface UI Using a Web BrowserGaining access to the User Interface UI Setup Network Web Server Help File AccessSelect Close/Exit Accessing the Web Browser UISelect Virtual Directory Select System ConfigurationSelect Special Functions Select Reset AP Select Save F1 to save the configurationUnder Configuration, select Security Select System Password Type the case sensitive AP nameSelect Easy Setup--Easy Setup Click Add/Delete Gateways Select Easy Setup--Easy SetupParameter Description Adding or Deleting a Range of Allowed Wireless Clients Adding Allowed Wireless ClientsAdding or Deleting Disallowed Wireless Clients Enabling or Disabling Encryption For the Short RF Preamble setting, click DisabledConsiderations Select Configuration--SecurityInterface Description Default Condition Enable or disable interfaces on the APFrequency No. of Channels Country Enter the Multicast Mask data and voice values Select Enabled or Disable All for All Snmp Traps Snmp Trap Description Default ValueConfiguring the Originating Modem Filtering to Forward Packets Configuring the Answering ModemFiltering to Discard Packets Disabling Type Filtering Removing Filtered Packet Types Networking ProtocolsClick Delete Filter Under Configuration, select FirmwareActive. Clear the wireless client association table for Special Function DescriptionWireless Clients Monitoring Wireless ClientsSelect Regular at the Wireless Clients prompt Indicates a 3Com voice-enabled device Latest version. Refer to Manually Updating AP Firmware on Ascii InterfaceVersions Configure the AP for the following Enable serial portArrow/Function Key Control Character To exit from submenus, press Esc Prompt DescriptionTo enable and configure the serial port connection on the AP Select Telnet LoginsPress Tab to select System Password Configuring The Serial PortHanging Up Setting DescriptionConfiguring the Dial-Up System Select Modem HangupInstallation WindowConfiguring the AP That can associate with this AP. The default is Disabled Wsaid Establishing a Connection PPP DirectPPP with Modems Answering AP Set the Connect Mode to AnswerOriginating AP From the answering APs UIFor automatic dial-out, reset the AP Range of Wireless Clients Press up/down arrows to toggle between range and individualEnable/Disable the ACL Removing Allowed Wireless ClientsRemoving All Allowed Wireless Clients Removing Disallowed Wireless Clients Load ACL from Wireless Client ListAdding Disallowed Wireless Clients Address FilteringClients from the AP Clearing WirelessSetting Logging OptionsAP Firmware Manually UpdatingPrevious version of AP firmware Select Alter Filenames/HELP URL/TFTP and press Enter Remainder of this procedure uses Windows 98 as an exampleType the firmware file name in the Download Filename field Select Transfer from the emulation program menu bar Open the Special Functions windowSelect Send File Download is complete when the UI displays Select Alter Filenames/HELP URL/TFTP Server and press EnterPerforming Pings Using MD5Authentication Extended RoamingEncryption Wireless client and the access pointHex-digit sequence Press the Tab key to highlight .Short RF Preamble Enabled Restoring ConfigurationsSelect Restore Factory Configuration Radio Characteristics Frequency No. of Channels Country Access Point SpecificationsPhysical Characteristics Output CharacteristicsNetwork Characteristics Online Technical ServicesTechnical Support World Wide Web SiteLatin America North AmericaTo obtain an RMA number, call or fax Page Index AsciiSnmp agent 3Com Corporation Limited Warranty 3Com AirConnect Access PointObtaining Warranty Regulatory Compliance Information Radio Frequency Interference Requirements CanadaImportant Read Before Using This Product 3Com End User Software License Agreement
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