3Com 09-1765-001 User Manual

AirConnect
®
®
Site Survey Administrator Guide
Version 1.5
http://www.3com.com/ http://www.3com.com/productreg
3Com Corporation ■
5400 Bayfront Plaza Santa Clara, California 95052-8145
Copyright © 2000, 3Com Corporation. All rights reserved. No part of this documentation may be
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UNITED STATES GOVERNMENT LEGEND
If you are a United States government agency, then this documentation and the software described herein are provided to you subject to the following:
All technical data and computer software are commercial in nature and developed solely at private expense. Software is delivered as “Commercial Computer Software” as defined in DFARS 252.227-7014 (June 1995) or as a “commercial item” as defined in FAR 2.101(a) and as such is provided with only such rights as are provided in 3Com’s standard commercial license for the Software. Technical data is provided with limited rights only as provided in DFAR 252.227-7015 (Nov 1995) or FAR 52.227-14 (June 1987), whichever is applicable. You agree not to remove or deface any portion of any legend provided on any licensed program or documentation contained in, or delivered to you in conjunction with, this User Guide.
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transferred from the U.S. or Canada without an approved U.S. Department of Commerce export license.
This product or software contains encryption code which may not be exported or
ONTENTS
C
P
REPARATION
1
Introduction 5 Inspecting the Survey Area 5
Environmental Considerations 6 Direct-Sequence Considerations 6
Antenna Placement Considerations 6
Site Electrical Considerations 7
Requesting a Site Survey 7
C
2
ONDUCTING A SITE SURVEY
Introduction 8 Site Survey Installation 8
CD-Rom Installation 8 AirConnect Wireless Network Trial 8 Starting the Site Survey Utility 9 Site Survey File Menu 10
Creating a New Site Survey 10
Selecting an Existing Site Survey 10
Defining a New Site Survey Area 10
Save/Save As 10
Upload/Download 10
Importing a Site Survey 10
Displaying Recent Site Surveys 10 Site Survey Edit Menu 11
Editing Site Survey Information 11
Editing Site Survey Area Properties 11
Editing Setup Properties 12
Setup Property Page 12 Meter Settings Property Page 12 Sounds Property Page 12 Logging Property Page 13
Navigating the View Menu 13
Viewing Adapter Info 13
Viewing Site Survey Area Info 13
Viewing Access Point Info 14
Viewing Mobile Unit Noise Info 14
Viewing Mobile Unit Signal Quality Info 14
Navigating the Area Menu 14
Creating a New Survey Area 14 Selecting and Editing an Existing Survey Area 14 Clearing the Text File Log for an Open Survey Area 14 Editing the Note File for an Open Survey Area 15 Running ICMP or WNMP Tests 15
Setting ICMP or WNMP Test Parameters 15 Setting New Test Parameters 16
AIRC
A
ONNECT OVERVIEW
Introduction 17 AirConnect Network Topologies 17
Peer-To-Peer Network 18 Same-Site Separate Networks 18 Single AP Bridge 19 Multiple-AP Full Coverage Network 20
Theory of Operation 20
MAC Layer Bridging 20
Filtering and Access Control 21 DHCP Support 21 Media Types 21 Bridging Support 22
PPP Connection 23 Direct-Sequence Spread Spectrum 24 Wireless Client Association Process 25 Mobile IP 26
Security 27 Supporting CAM and PSP Stations 27 HTTP, HTML Web Server Support 28 Management Options 28
Programmable SNMP Trap Support 29
Using SNMP 29
Increased MIB Support 29
Using the User Interface 30
1
REPARATION
P

Introduction

Inspecting the Survey Area
Installing an AirConnect wireless network begins with conducting a site survey. A site survey involves the use of the AirConnect Site Survey utility to determine the physical requirements for a site-specific AirConnect wireless network. A site survey analyzes the installation environment and provides users with recommendations for equipment and placement. The site may be a warehouse, manufacturing plant, office building, or retail space.
The AirConnect Site Survey utility determines the location of APs, as well as the number necessary to provide optimal coverage. Only qualified site survey technicians should use the AirConnect Site Survey utility to conduct site surveys.
When installing an AirConnect network, complete coverage may require multiple antennas. If the facility is small, or the coverage area is free from physical obstructions, one AP and antenna might be sufficient.
If you are unfamiliar with the AirConnect wireless infrastructure and the components that compose it, refer to Appendix A AirConnect Overview for an overview of AirConnect technology.
During the planning stages of the site survey, a representative from the site survey team will visit the proposed AirConnect radio coverage site. As a standard practice in the site survey consultation, the representative gathers facility drawings and completes a Site Survey Requirements document and a site survey questionnaire. The representative documents the wiring used within the facility (10BaseT, 10Base2, fiber optic) and assesses its applicability to AirConnect components.
Several trial installation areas should be selected. The site survey team analyzes each proposed installation area to document radio transmission constraints and to develop preliminary AP placement alternatives to be tested during the actual site survey. The findings from the initial site inspection should be documented in a Site Survey Request Form and serve as the outline of the site survey.
The following variables should also be considered in the site survey requirements definition:
RF systems already in use
Location of host system(s)
Available AC power
Interfering metal fire breaks and wall structures
Doorways and passages causing RF propagation
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The completion of the RF Site Survey Requirements document is a coordinated effort between the site survey team and the customer management team.
The RF Site Survey Requirements document does not identify potential installation constraints within the customer site, nor does it recommend AP and antenna placement location. The RF Site Survey Requirements document represents a preliminary overview of the customer site, and is used as a baseline for refining site survey requirements.
Environmental
Considerations
Direct-Sequence
Considerations
The site survey team selects trial AirConnect component installation areas away from transformers, heavy-duty motors, fluorescent lights, microwave ovens, refrigerators, and other industrial equipment. Areas with excessive moisture, heat, and dust are inappropriate for installing an AirConnect wireless network.
Signal loss can occur when metal, concrete, walls, or floors block AP transmission areas. AirConnect AP antennas are trial-mounted in open areas or added to an existing AP to boost the AirConnect coverage area.
The positioning of an AP depends on the floor plan of the site. The site survey team makes AP placement recommendations based on the following installation site variables:
Indoor installation site
Large or small proposed radio coverage area
Wide or narrow proposed coverage area
Open coverage area or area with documented obstructions
In a direct-sequence radio coverage cell, APs with identical direct-sequence channels cannot share the same cell. Direct-sequence access points operating on different channels require careful survey area testing to ensure that radio transmissions do not interface.

Antenna Placement Considerations

Radio coverage requirements relate directly to installation site constraints. With an omnidirectional antenna, the radio range of the AP (transmitting at 1Mbps) could have a radius up to 1000 feet (303 meters) in open areas. However, in office or retail environments, obstructions can reduce the coverage to a radius of 180 to 250 feet (54 to 76 meters). The coverage area is also referred to as a cell.
The final location of AP antennas is critical to the successful operation of the system. When conducting the survey, consider the exact conditions in the installation area. These conditions include all losses due to cabling and connectors.
Requesting a Site Survey 7
Site Electrical
Considerations
AirConnect APs draw power from wall outlets or over CAT 5 cabling using the AirConnect PowerBASE-T adapter. AP performance is subject to degradation due to inherent or random electrical problems or site-specific disturbances.
The following AirConnect AP electrical installation alternatives are listed from optimal to preferred for a particular installation area:
Isolated ground circuit with online, uninterruptable power supply (UPS) that also
1
acts as filter and surge suppressor
Isolated ground circuit with surge suppressor
2
Dedicated circuit with UPS
3
Dedicated circuit with surge suppressor
4
3Com recommends using one of the preceding installation alternatives when using a Network Controller Unit. Deviation from theses options can cause data loss and serious transmissions problems.
NOTE:
The AP must be provided with power 24 hours a day. 3Com recommends
that AP power never be provided from an Energy Management System.
If a nondedicated circuit is necessary, 3Com recommends that the circuit does not support the following:
Requesting a Site Survey
Hard wired devices
Devices with components intended or known to produce heat (space heaters,
laser printers, heat guns, soldering irons, etc.)
Single devices drawing more than 20% of the rated value of the circuit
Multiple devices drawing a total of more than 60% of the rated circuit value
The Site Survey Request Form contains detailed information about a customer, the 3Com Sales Associate representing that customer, an updated floor plan of the customer facility, host operating system considerations, and the quantity and type of AirConnect components being installed.
2
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C
S
ITE
URVEY
S

Introduction

Site Survey Installation

CD-ROM Installation

1
2
3
4
5
6
The AirConnect Site Survey utility is used to establish a two-way data network using both stationary and mobile devices at various points within the proposed radio coverage area. Assess AP signal strength using various AP configurations.
The AirConnect Site Survey utility runs under Windows 95/98, and NT.
A site survey requires the AirConnect Site Survey utility be loaded on the wireless clients and the desktop computer used in the survey.
To install the AirConnect Site Survey utility from CD-ROM:
Insert the Administrator CD-ROM in the CD-ROM drive.
Click Start and select Run.
x:\Admin\SSurvey\Disk1\Setup.exe
Enter
where “x” represents the letter assigned to the CD-ROM drive.
Click OK.
Complete the installation following the instructions provided with the AirConnect Site Survey utility.
Select Yes when asked if backup copies of replaced files are required.
Selecting Yes invokes the site survey utility uninstall feature for possible use.

AirConnect Wireless Network Trial

The AirConnect Site Survey utility installation is completed. Launch the site survey utility by clicking on the program icon appearing on the Windows desktop.
Before using the AirConnect Site Survey utility, an AirConnect wireless LAN infrastructure is created to test AirConnect component radio signal strength.
In addition to the AirConnect Site Survey utility, the following equipment is required to create an AirConnect wireless network:
AirConnect Access Points
Laptop computer
PowerBASE-T and AC power supply
CAT 5 cable
Access Point mounting bracket
AirConnect wireless clients with extra batteries
Starting the Site Survey Utility 9
To install a trial AirConnect wireless network, use the following procedure.
Mount the APs.
1
Mount APs at the locations recommended on the floor plan drawing. Start with the most difficult coverage area first. Position the APs so that their antennas are not obstructed.
Power on the APs.
2
Use the PowerBASE-T and interconnecting 8-wire CAT 5 cable if an AC wall socket is not conveniently located.
Observe AP LED behavior.
3
Check the LEDs to verify normal boot operation. After the boot cycle is complete, the STATUS LED flashes approximately once every second to indicate that the AP is operating properly.
Power on the AirConnect wireless clients to be used for the site survey.
4

Starting the Site Survey Utility

NOTE:
AirConnect mobile devices used to perform the survey.
When the device is powered on, a message indicating the AP is not connected to a boot server will be displayed. This is normal, since the AP is not yet connected to an Ethernet network.
Set the AirConnect AP and wireless client Network IDs.
5
Set the wireless client(s) and AP to the same Net ID.
An AirConnect wireless network now exists and can be tested for radio transmission effectiveness with the AirConnect Site Survey utility.
Click the AirConnect Site Survey utility icon from the Windows desktop to launch the utility. The Site Survey utility Welcome dialog box appears.
You can use the Site Survey utility Welcome dialog box to open an existing site survey area workspace, create a new workspace, create a new workspace from an existing site survey area workspace, or open a recently used workspace.
If an existing site survey workspace is opened containing one or more survey areas, the Site Survey Test dialog box displays. Use the Site Survey Test dialog box to specify the ICMP and WNMP test parameters for the survey area. If an existing survey workspace does not have a survey area defined, the Site Survey dialog box displays. Use the Site Survey dialog box for entering the site survey area name, surveyor, and description. The Site Survey Test and Site Survey dialog boxes are described in greater detail in the sections that follow.
The AirConnect Site Survey utility should already be loaded on the
Closing the Welcome dialog box enables the File, Edit, View, Area, and Help pull-down menus. Use these menus to create a new site survey, view radio coverage areas within an existing site survey template, run a ping test for a survey area, display and configure the Edit menu property pages, and display help information for the usage of the utility.
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Site Survey File Menu

Creating a New
Site Survey
Selecting an Existing
Site Survey
Defining a New Site
Survey Area
Use the File menu to create a new survey area workspace, open an existing survey workspace, define a new survey area, save the survey workspace, upload/ download existing survey workspace data, import survey workspace data, and display recent survey information.
Select
New Site Survey
in the File menu to open a Site Survey dialog box. Use the Site Survey dialog box to enter the site name, surveyor, and description. If a workspace is open, the user is prompted to save the existing workspace first. ClickOK to display the new workspace name in the status bar at the bottom of the screen
Select
Open Site Survey
in the
menu to open a dialog box displaying files
File
with the extension “.ssw.” If an invalid file is read, an error message displays; otherwise, a progress dialog box is shown and the workspace is loaded. The Site Survey Test dialog box generates if the workspace has at least one defined area. The Site Survey Area dialog box displays if the existing workspace does not have a defined area. The status bar displays the workspace and area name.
Select
New Area
in the File menu to display a
Site Survey Area
dialog box. Use the Site Survey Area dialog box to enter the area name and description. The Delete button is grayed when defining a survey area. The Test Name field lists the tests defined for that area. Add a new test by clicking the ellipsis () button. An error message displays if the Area Name field is left blank or the name of an existing area is entered. The area name displays at the bottom of the screen.

Save/Save As

Upload/Download

Importing a Site Survey

Displaying Recent
Site Surveys
Select name. Select
Select
in the File menu to save the open survey using the existing survey
Save
in the File menu to save the survey using a different name.
File Save As
dialog box. Use the Save As
Upload
Save As
in the File menu to display a dialog box to indicate the target destination for the site survey workspace files. A pop-up dialog box indicates the results of the file upload.
Select
Download
in the File menu to display a
dialog box. Use the dialog box
File
to navigate to the location of the site survey workspace on the desktop computer. A pop-up dialog box indicate the results of the file download.
Select
in the File menu to display an
Import
Import Areas and Tests
dialog box. Use the Import Areas and Tests dialog box to import survey areas and/or tests from another survey workspace. Select
Import Areas
older survey workspace files with updated ones. Click the
and/or
Import Tests
button to display
Import
to replace
a dialog box displaying files with the extension “.ssw.”
Select
Recent Site Surveys
in the File menu to display the last four site survey workspace files created or accessed. Selecting any workspace in the list loads that workspace. If there is at least one area defined for the workspace, the Site Survey Test dialog box displays it. The status bar at the bottom of the dialog box displays the status, filename, area name, and workspace name. If a workspace is already open, the user is prompted to save the existing workspace first.
Site Survey Edit Menu 11

Site Survey Edit Menu

Editing Site Survey
Information
The Site Survey utility Edit menu contains Site Survey, Area, and Settings pull-down menus.
Use these menus to edit an open AirConnect site survey, display a list of coverage areas within the survey, and use the Setup, Meter Settings, Sounds and Logging property pages to configure surveyor, system sounds, and test data logging information.
Select
Site Survey
in the Edit menu to display the Site Survey dialog box. Use the Site Survey dialog box to enter the site name, surveyor, and description. If a workspace is already open, the user is prompted to save the existing workspace. Click OK to display the new workspace name.
Surveyor. Enter the surveyor name in the
Surveyor
field to automatically update the New Site Survey dialog box. Click OK to save the updated surveyor name in the registry for subsequent surveys.
ICMP Host Addr. Enter an ICMP Host Address in the field provided (not needed for WNMP ping tests). The default address is the default address of the AP.
Ping Count. Enter the number of pings to be transmitted during the ping test in the Ping Count field. The default Ping Count is 100, with a maximum of 2000.
Rerun Count. Enter the number of times the ping test is transmitted in the Rerun Count field. The default Rerun Count is 100. The rerun can be continuous
Editing Site Survey
Area Properties
Packet Size. Enter the packet size transmitted during the ping test in the Packet Size field. The default Packet Size is 128 bytes, with a maximum of 1472 bytes.
Threshold Time. Enter the maximum acceptable time to send out and receive the total number of pings for each test in the Threshold field. Choose a Threshold Time from1 second to 3600 seconds. The default Threshold Time for 100 pings is 13 seconds.
Auto Rerun. If
Auto Rerun
is activated, the Site Survey utility test suite (in either
Automatic or Manual mode) runs continually until the surveyor stops the tests.
Select
in the Edit menu to display the Site Survey Area List dialog box. Use
Area
the Site Survey Area List dialog box to display a list and description of survey areas. Select an area and click
Edit Area
to display the Site Survey Area dialog box. Add new tests and survey area descriptions as needed. Click OK to save the changes to the site survey workspace. Click
to remove the area from the current site
Delete
survey workspace.
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Editing Setup Properties

Select
Settings
in the Edit menu to access the Setup, Meter Settings, Sounds, and Logging tabs. Use these dialog boxes to change default settings for the current site survey workspace.
Setup Property Page
Select the Setup tab to change the following default site survey workspace information:
Edit Note on Error.
Activate
Edit Note on Error
to display a pop-up dialog box for entering notes when an error condition is detected during the site survey ping test. Undocumented physical barriers (metal or block walls) could exist that the surveyor can describe as a possible reason for signal deflection and test failure. The reason for the error is automatically created as part of the note.
Override All Test ICMP Host Addresses.
Check this box to use the ICMP host address entered on this page for all tests. Checking this box does not replace the host address saved for each test
Meter Settings Property Page
Select the
Meter Settings
property page to set bounds (thresholds) for the signal quality gradient bars in the Round Trip, Missed Beacon, and Transmit Retry fields. The circular RTT Avg, Missed %, and Retry % indicators on the Site Survey Test dialog box show green if the average of the previous tests (20 tests for RTT Avg, 40 tests for Retry %, and 20 tests for Missed %) is below the lower threshold.
The circular indicators on the Site Survey Test dialog box show red if the average of the previous 30 tests is above the upper threshold. Test results between the bounds set on the Meter Settings property page result in Yellow displays on the circular indictors on the Site Survey Test dialog box.
Sounds Property Page
Select the
Sounds
property page to change the following default site survey
workspace information:
Play on Timeout.
Select
Play on Timeout
to emit an audible timeout tone every
time a ping test timeout is reached.
Play on Roam.
Select
Play on Roam
to emit an audible roaming tone every time
an wireless client roams between APs.
Play on Threshold.
Select
Play on Threshold
to emit an audible threshold tone
every time the threshold time is met or exceeded.
Play on Test Complete.
Select
Play on Test Complete
to emit an audible test
complete tone every time a suite of ping tests has been transmitted.
The default for the Sounds property page is all sounds enabled. Set the volume level and/or sound by using the Windows Control Panel Volume and Sounds applet or the Sounds task tray applet.
Logging Property Page
Select the workspace logging information.
Logging
property page to change the following default site survey
Navigating the View Menu 13
Enable Logging. Select Detailed Logging Format. If unchecked, no logging takes place during the ping tests. The default is Short Logging Format. Short logging provides an overview of ping transmission test activity. Detailed logging provides a comprehensive review of ping test activity.
Short Logging Format. Select consisting of the site survey workspace and area name, the surveyor name, date, test start and end time, AP BSSID, packet size, ping count, and test totals. The test totals section indicates elapsed test time, the number of retries, roundtrip ping transmission time, and the number of timeouts. If an out-of-range condition exists, it is also logged.
Detailed Logging Format. Select added to the Short Log content. Device roaming information, survey and site area descriptions, and error log notes are included in the Detailed Log.
Clear Log contents before each test. Select test to automatically clear the content of the log before a test suite is run.
Confirm before log contents are cleared. If activated, the surveyor is prompted to decided whether the log file should be cleared before the test suite is run.
Enable Logging
Short Logging Format
to enable Short Logging Format or
to generate a text file
Detailed Logging
to generate a text file
Clear Log
contents before each
Navigating the View Menu

Viewing Adapter Info

Viewing Site Survey
Area Info
The Site Survey utility View menu contains Adapter Info, Areas, Known APs, Noise Meter, and Signal Quality pull-down menus.
Use the pull-down menus to view AirConnect WLAN adapter driver and firmware data, site survey areas, APs within range of a target AirConnect mobile device, or a graph depicting wireless client signal quality. You can also create a text file of the log file.
Select
Adapter Info
box. Use the Adapter Information dialog box to display AirConnect WLAN adapter driver and firmware version, adapter type and firmware type. The information is view only and cannot be modified.
Select the Site Survey Area List dialog box to display a list and description of survey areas. Select an area and click Edit Area to display the Site Survey Area dialog box. Add new tests and survey area descriptions as needed. Click OK to save the changes to the site survey workspace. Click survey workspace.
in the View menu to display the Site Survey Area List dialog box. Use
Areas
in the View menu to display an Adapter Information dialog
to remove the area from the current site
Delete
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Viewing Access
Point Info
Viewing Mobile Unit
Noise Info
Viewing Mobile Unit
Signal Quality Info
Select
Known APs
in the View menu to display APs in range of the target wireless client. Use the Known APs dialog box to view the AP BSSID, number of associated wireless clients, wireless client type, and status and data rate. An icon next to each AP indicates whether the AP is mandatory or preferred and if the AP is associated. A list of APs within range of the wireless client is also shown. Select an AP and right click to change the AP type to Mandatory or Roaming. Click the
Rates
button to display the Transmission Rates dialog box. Use the Transmission Rates dialog box to set the transmission rate to 1Mb, 2Mb, 5.5Mb or 11Mb. Checking multiple rates defaults the wireless client to a lower rate if the higher rate AP association cannot be established. At least one rate is required.
Select
Noise Meter
indicator
(RSSI) values and channel numbers. Use the Noise Meter dialog box to
in the View menu to display a graph of
relative signal strength
view the wireless client BSSID and the RSSI minimum, maximum, and average values. The RSSI values displayed in the graph are continuously updated with the last 6 received values displayed in blue. Click
to reset the graph to zero and
Reset
begin a new display as RSSI values are received.
Select
Signal Quality
in the View menu to display the percentage of missed beacons, the percentage of transmission retries and the percentage of CRC errors logged during the ping test. Use the Signal Quality dialog box to display the strength of the radio signal transmitted by an AP. This information is useful in determining if the trial site survey AP placement locations are effective for providing radio coverage to the proposed radio coverage area.
Navigating the Area Menu
Creating a New
Survey Area
Selecting and Editing an
Existing Survey Area
Clearing the Text File
Log for an Open
Survey Area
The Site Survey utility Area menu contains New, Select, Clear Log Contents, Edit Notes, Run ICMP Test, and Run WNMP Test menu items.
Use the menu items to create and edit a site survey area, view the settings of a survey area, clear a site survey log, edit or delete notes in a survey log, and start and stop ICMP and WNMP tests.
Select
in the Area menu to display a Site Survey Area dialog box. Use the Site
New
Survey dialog box for entering a survey area name and description. If a workspace is already open, you are prompted to save the existing workspace. Click OK to display the new workspace name.
Click
in the Area menu to display the Site Survey Area List dialog box. Use
Select
the Site Survey Area List dialog box to display a list and description of survey areas. Select an area and click Edit Area to display the Site Survey Area dialog box. Add new tests and survey area descriptions as needed. Click OK to save the changes to the site survey workspace. Click
to remove the area from the current site
Delete
survey workspace.
Use the
Clear Log Contents
option to delete the log contents for the active survey
workspace.
Navigating the Area Menu 15
Editing the Note File for
an Open Survey Area
Running ICMP or
WNMP Tests
Select
Edit Note
in the Area menu to display the notes file for the active survey area. Use the Edit Note option to edit or delete the survey test notes entered for the active survey workspace.
Select
Run ICMP Test
or
Run WNMP Test
in the Area menu to display the Site
Survey Test dialog box.
Use the Site Survey Test dialog box to specify ICMP or WNMP test parameters. ICMP and WNMP tests are ping tests assessing radio transmission roundtrip, delay time and transmission signal strength.
Setting ICMP or WNMP Test Parameters
Use the Site Survey Test dialog box to set the following ICMP or WNMP test parameters:
Access Point. the Access Point field of the Site Survey Test dialog box lists the associated AP. Choose a different access point from the list of available APs by clicking the ellipsis () button.
Area. Define a new survey area by clicking the ellipsis button next to the Area pull-down menu.
Tes t. Use the Test pull-down menu to list the tests defined for the active survey area. Use the ellipsis button to open a dialog box or entering new test settings.
Test Statistics Use the Test Statistics field of the Site Survey Test dialog box to view the total ping roundtrip time, the number of tests remaining in the run, the number of test runs remaining, and the ping test transmit data rate.
Four graphs on the bottom of the Site Survey Test dialog box display an average roundtrip time, missed beacon percentage, retry percentage, and threshold percentage. Bounds (thresholds) set in the Meter Settings property page establish the limits for the variables in the graphs.
Results List Box Use the Results List Box to view ping count, errors, retry percentage, roundtrip time, and missed beacons values. Scroll backward or forward in the list. The list displays the last test suite run.
Start. Click
to begin the ICMP or WNMP test. Once started, the Start
Start
button changes to a Stop button.
Edit Note. Click
Edit Note
to display a dialog box for entering notes for the test.
Each note is added to the log file.
Clear List. Use the
Clear List
button in Site Survey Test dialog box the clear the
results list box.
Tes t Totals. Click the
Test Tota l s
button within the Site Survey Test dialog box to
display the Site Survey Totals dialog box.
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Use the Site Survey Totals dialog box to display survey area final test results, including test start time, total number of tests, total number of runs, total test roundtrip time, average test roundtrip time, and total number of timeouts. The two checkboxes indicate if the user cancelled the test run and whether the test was run to completion.
Setting New Test Parameters
Open the New Test Settings dialog box by clicking the ellipsis button next to the Test pull-down menu in the Site Survey Test dialog box.
Use the New Test Settings dialog box to enter a test name, define test packet sizes, select a test ping count, enable the test Auto Rerun, Sounds and Logging features, change host address information and display the Settings property pages.
Test Nam e.
Use the Test Name field in the New Test Settings dialog box to enter
the test for the active survey workspace.
Packet Size.
Use the Packet Size field in the New Test Settings dialog box to
enter a packet size for the ICMP or WNMP test.
Ping Count.
Use the Ping Count field in the New Test Settings dialog box to
type in a ping count value for the ICMP or WNMP test.
Threshold.
Use the Threshold field in the New Test Settings dialog box to type in
threshold value for the ICMP or WNMP test.
Host Address
The host address entered in the Settings Setup property page
displays in the Host Address field. Change the host address value by typing it in.
Auto Rerun.
Select the
Auto Rerun
option in the New Test Settings dialog box
to enable the Auto Rerun test feature.
Enable Sounds.
Select the
Enable Sounds
option in the New Test Settings
dialog box to enable the Sounds feature.
Logging.
Select the
Logging
option in the New Test Settings dialog box to
enable the Logging feature.
Advanced.
Click the
Advanced
button in the New Test Settings dialog box to
access the Settings property pages for the active survey area workspace.
A
AIRC
ONNECT
VERVIEW
O

Introduction

AirConnect Network Topologies

AirConnect from 3Com is made up of a series of products that work together to deliver high-speed digital wireless networking. This technology provides connectivity between wireless clients and network nodes in a variety of indoor environments, and also provides bridging architecture between wired and wireless network segments. AirConnect is based on the IEEE 802.11HR standard, and delivers 11 Mbps data transfer rates.
The core hardware products that make up an AirConnect network include the following:
PC card, installed in a wireless client (laptop or desktop computer)
Access point, or AP, which serves as a wireless network node
PowerBASE-T (optional), which provides bus power to the access point when
connected to an Ethernet network
Also included in your AirConnect kit are an AP mounting bracket and hardware, a serial cable, a power adapter and associated power cables, and two CDs: the AirConnect Administrator CD, and the AirConnect User CD.
To better understand how the various AirConnect products work together to create a wireless network, it might be helpful to depict a few of the possible AirConnect network topologies. The topology used in a particular environment depends on many factors, such as the functionality of the AP in the network, or desired data transfer rates. Your AirConnect network topology will probably resemble one of the following scenarios, or perhaps a combination of two or more.
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Peer-To-Peer Network

The simplest AirConnect topology consists of one AP providing a single-cell network for wireless clients. In this scenario, as shown in the following figure, the wireless clients (laptop and desktop computers with the AirConnect NIC installed) communicate through the AP on a peer-to-peer network. The clients can be moved anywhere within the coverage area of the AP, and still communicate with each other. The AP in this instance serves the same purpose as a stand-alone network hub, and is not connected to any other network segments.
Same-Site Separate
Networks
In this scenario, as shown in the figure below, Multiple APs can coexist as separate networks at the same site without interference using different network identifiers (wireless LAN service areas). The wireless clients can move within the coverage area of one AP and remain connected, or can roam (if configured to do so) to the coverage area of a different AP, and communicate with the wireless clients associated with that AP.
AirConnect Network Topologies 19

Single AP Bridge

Another possible AirConnect topology is a single AP bridging an Ethernet and wireless network. As shown in the next figure, the AP, wired to a network server or LAN through an Ethernet cable, serves as a network node and provides the link between the server and the wireless clients. The wireless clients can move freely throughout the coverage area of the AP while remaining connected to the server.
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Multiple-AP Full
Coverage Network
This network topology will be used in most enterprise environments: multiple APs wired to an existing LAN to provide complete wireless network coverage. In this scenario, as shown in the next figure, wireless clients can roam seamlessly between different coverage areas and remain connected to the network.

Theory of Operation

MAC Layer Bridging

To improve AP management and performance, you should understand basic AP functionality and configuration options. The AP includes features for different interface connections and network management.
The AP provides
MAC layer bridging
between its interfaces. The AP monitors traffic from its interfaces and, based on frame address, forwards the frames to the proper destination. The AP tracks the frames sources and destinations to provide intelligent bridging as wireless clients roam or network topologies change. The AP also handles broadcast and multicast message initiations and responds to wireless client association requests.
The AP listens to all packets on all interfaces and builds an address database using the unique IEEE 48-bit address (MAC address). An address in the database includes the interface media that the device uses to associates with the AP. (The AP internal stack interface handles all messages directed to the AP.) The AP uses the database to forward packets from one interface to another. The bridge forwards packets addressed to unknown systems to the default interface (either Ethernet or PPP).
Each AP stores information on destinations and their interfaces to facilitate
forwarding
. When you send an
Address Resolution Protocol
(ARP) request packet, the AP forwards the request over all enabled interfaces (Ethernet, PPP, or radio), except over the interface on which the ARP request packet was received. (Radio-received ARP request packets echo back to other APs over radio.)
Upon receiving the ARP response packet, the AP database keeps a record of the destination address along with the receiving interface. With this information, the AP forwards any directed packet to the correct destination. The AP forwards packets for unknown destinations to the Ethernet interface.
Theory of Operation 21
The AP removes from its database destinations or interfaces not used for a specified time. The AP refreshes its database when it transmits or receives data from these destinations and interfaces.
Filtering and Access Control
The AP provides facilities to limit the wireless clients that associate with it and the data packets that can forward through it. Filters provide network security or improve performance by eliminating broadcast/multicast packets from the radio network.

DHCP Support

The
Access Control List
(ACL) contains MAC addresses for wireless clients allowed
to associate with the AP. This provides security by preventing unauthorized access.
The AP also uses a
disallowed address
list of destinations. This feature prevents the AP from communicating with specified destinations. This can include network devices that do not require communication with the AP or its wireless clients.
Depending on the setting, the AP can keep a list of frame types that it forwards or discards. The
Type Filtering
option prevents specific frames (indicated by the 16-bit DIX Ethernet Type field) from being processed by the AP. These include certain broadcast frames from devices unimportant to the wireless LAN but which utilize bandwidth. Filtering out unnecessary frames also improve throughput.
The AP uses
Dynamic Host Configuration Protocol
(DHCP) to obtain a leased IP address and network configuration information from a remote server. DHCP is based on BOOTP protocol. DHCP can coexist or interoperate with BOOTP. An AP sends out a
DHCP request
searching for a
DHCP server
to acquire the network configuration and firmware filenames. Because BOOTP and DHCP interoperate, the one that responds first becomes the server that allocates information. The DHCP client automatically sends a DHCP request to renew the IP address lease as long as the AP is running. (This parameter is programmed at the DHCP server. For example, Windows NT servers typically are set for 3 days.)
The AP can optionally download two files when a boot takes place, the firmware file and an HTML file, because firmware versions 4.00-31 and above support Web servers. Users can program the DHCP or BOOTP server to transfer these two files when a DHCP request is made.

Media Types

When the AP receives a network configuration change or is not able to renew the IP address lease the AP sends out an SNMP trap.
The AP supports bridging between Ethernet, radio, and serial media.
The
Ethernet interface
fully complies with Ethernet Rev. 2 and IEEE 802.3 specifications. The AP supports 10BASE-T wired connections and full-speed filtering. The data transfer rate over radio waves is 11 Mbps. The Ethernet interface is optional for single-cell or PPP-connected networks.
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Bridging Support

The
radio interface
conforms to IEEE 802.11 HR specifications. The interface operates at 11 Mbps using direct-sequence radio technology. The AP supports multiple-cell operations with fast, transparent roaming between cells. With the direct-sequence system, each cell operates independently. Each cell provides a 11 Mbps bandwidth. Adding cells to the network provides increased coverage area and total system capacity. The AP supports wireless clients operating in
Save Polling
(PSP) mode or
Continuously Aware Mode
(CAM) without user
Power
intervention.
The
Protocol
DB-9
, 9-pin,
RS-232 serial port
provides a
User Interface
(UI) or a
Point to Point
(PPP) connection. The UI provides basic management tools for the AP. The
PPP provides a link between APs using a serial connection. The serial link supports
short haul
(direct serial) or
Terminal Equipment
long haul
(DTE) device with male pin connectors for the RS-232 port.
(telephone line) connections. The AP is a
Data
Connecting the AP to a PC requires a null-modem cable; connecting the AP to a modem requires a straight-through cable.
The AP PPP interface, accessible from the serial port at the rear of the AP, provides two types of bridging operations:
Internet Protocol
(IP) bridging between an AP and a computer, and between two APs (with one AP connected to a LAN). To establish an Internet Protocol bridge with an AP, ensure that the computer includes the appropriate Telnet software with PPP and TCP/IP protocols. Using Telnet, a remote computer can connect to any AP on an Ethernet network, as long as data transfers through IP packets.
A PPP link provides the option of using a direct serial link or modem to extend wired Ethernet topologies. Once in PPP mode, the AP automatically attempts to communicate with the other device using the
Data-Link Bridging
(DLB) protocol. An AP using DLB communicates on the MAC level, and receives and transmits Ethernet frames.
If the other device does not support DLB, the AP attempts to communicate using
Internet Protocol Control Protocol
(IPCP). An AP using IPCP communicates on the
IP level, and receives and transmits IP packets.
The PPP implementation in the AP uses the
Network Control Protocol
RFC 1171: the Point-to-Point Protocol, July 1990
RFC 1220: PPP Extensions for Bridging, April 1991
RFC 1332: The PPP Internet Protocol Control Protocol, May 1992
RFC 1661: The Point-to-Point Protocol, July 1994
(RFCs are
Requests For Comments
(NCP) as described in:
used in Internet Communities.)
Link Control Protocol
(LCP) and
The AP database dynamically tracks wireless clients and APs on the PPP interface. Packets forward to the PPP link after the AP determines their destination.
Theory of Operation 23
The PPP implementation in the AP uses the NCP as described in RFC 1220: PPP Extensions for Bridging to encapsulate packets at the Ethernet level. The PPP provides IP bridging control as defined by RFC 1172 and MAC-level bridging. The protocol provides support for PPP negotiations conforming to RFC 1661. Users cannot plug a non-AP node directly into the AP serial port, only AP-to-AP PPP links.
For detailed information, refer to
RFC 1171: The Point to Point Protocol and RFC
1220: PPP Extensions for Bridging.
PPP Connection
Connecting an AP and a computer with a direct serial link requires the use of a null-modem serial cable.
Null-modem serial cable pinout:
Connecting an AP and computer with modem devices requires the use of straight-through cables between the APs and modems. Using modems requires a telephone line for as long as the link remains active.
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Straight-through cable pinout:
Direct-Sequence
Spread Spectrum
When using a modem connection, one AP represents the originating AP and the other represents the answering AP. When using a PPP link, do not use the serial port to access the UI. Access to the UI requires establishing a Telnet session with the AP.
Direct Sequence Spread Spectrum
(DSSS) uses a high-speed, non-information bearing signal to spread the transmitted information over a segment of the radio frequency band or spectrum. The AirConnect access point uses DSSS for radio communication.
Direct-sequence systems communicate by continuously transmitting a redundant pattern of bits called a into
by the access point to find the chipping sequence corresponding to the
chips
chipping sequence
. Each bit of transmitted data is mapped
output signal.
Wireless clients receiving a direct-sequence transmission use the same chipping sequence to recreate the original data transmitted by the access point. Intercepting and decoding a direct-sequence transmission requires a predefined algorithm to associate the chipping sequence used by the transmitting access point to the receiving wireless client. This algorithm is established when the access point and wireless client are configured. The bit redundancy within the chipping sequence enables the receiving wireless client to recreate the original data pattern, even if bits in the chipping sequence are corrupted by interference.
Theory of Operation 25
Wireless Client
Association Process
APs recognize wireless clients as they associate with the AP. The AP keeps a list of the wireless clients it services. Wireless clients associate with an AP based on the following conditions:
Signal strength between the AP and wireless client
Wireless clients currently associated with the AP
Wireless client Supported Rate (see the table below)
Positive match between the wireless client and encryption keys (optional)
Positive wireless client authorization by the Access Control List (optional)
The following table gives the wireless client support rates:
Data Rate Requirement
11 Mbps Optional
5.5 Mbps Optional
2 Mbps Optional
1 Mbps Required
Wireless clients perform preemptive roaming by intermittently scanning for APs and associating with the best available AP. Before roaming and associating with APs, wireless clients perform scans to collect AP statistics and determine the direct-sequence channel used by the AP.
Scanning is a periodic process where the wireless client sends out messages on all frequencies defined by the country code. The statistics enable a wireless client to reassociate by synchronizing its frequency to the AP. The wireless client continues communicating with that AP until it needs to switch cells or roam.
Wireless clients perform scans at start-up. In a scan, a wireless client uses a sequential set of channels as the scan range. For each channel in range, the wireless client tests for
Clear Channel Assessment
(CCA). When a transmission-free channel becomes available, the wireless client broadcasts a probe with the wireless LAN service area and the broadcast HSA_ID. An AP-directed probe response generates a wireless client
Acknowledgment
(ACK) 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.
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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.

Mobile IP

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, 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.
Mobile IP 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.
Mobile IP is like giving an individual a local post office forwarding address when leaving home for an extended period. When mail arrives for the individual home address, it is forwarded by the local post office to the current care-of-address. Using this method, only the local post office requires notification of the individual current address. While this example represents the general concept of Mobile IP operation and functionality, it does not represent the implementation of Mobile IP used.
A tunnel is the path taken by the original packet encapsulated within the payload portion of a second packet to some destination on the network.
A
Home Agent
is an AP acting as a router on the wireless client home network. The home agent intercepts packets sent to the wireless client home address and tunnels the message to the wireless client at its current location. This happens as long as the wireless client keeps its home agent informed of its current location on some foreign link.
A
Foreign Agent
is an AP acting as a router at the wireless client location on a foreign link. The foreign agent serves as the default router for packets sent out by the wireless client connected on the same foreign link.
A care-of-address is the IP address used by the wireless client visiting a foreign link. This address changes each time the wireless client moves to another foreign link. It can also be viewed as an exit point of a tunnel between the wireless client home agent and the wireless client itself.
Theory of Operation 27
Supporting CAM and
PSP Stations
The
AirConnect Mobile IP (roaming across routers)
feature enables a wireless client on the Internet to move from one subnet to another while keeping its IP address unchanged. 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.
Set the wireless client for Mobile IP as specified in the
Interface User Guide
.
AirConnect Network
Security
Security involves two distinct areas: authentication and privacy. Authentication ensures that only authorized users access the wireless network. Privacy ensures that communication between authenticated users and the network cannot be intercepted or overheard. The Access Control List provides authentication using the wireless LAN service area and a system administrator-supplied list of all the wireless client MAC addresses authorized to access the Home Service Area. Privacy is ensured by enabling the 40-bit WEP encryption option.
Continuously Aware Mode
(CAM) stations leave their radios on continuously to hear every beacon and message transmitted. These systems operate without any adjustments by the AP.
A
beacon
is a uniframe system packet broadcast by the AP to keep the network synchronized. A beacon includes the wireless LAN service area, the AP address, the Broadcast destination addresses, a time stamp, the
Traffic Indicator Message
Power Save Polling
(PSP) stations power off their radios for long periods. When a
(TIM).
Delivery Traffic Indicator Maps,
and
wireless client in PSP mode associates with an AP, it notifies the AP of its activity status. The AP responds by buffering packets received for the wireless client. The PSP-mode wireless client wakes up to listen to the AP beacon every
Interval
where
is a PSP-mode value from the 1 to 5-range; the
n
th
Beacon
n
Beacon Interval
is set on the wireless client. When the wireless client wakes up and sees its bit set in the TIM, it issues a poll request to the AP for packets stored for it. The AP sends them to the wireless client and the wireless client goes back to sleep. A DTIM field, also called a countdown field, informs wireless clients of the next window for listening to broadcast and multicast messages. The AP sends the messages following the
nth beacon
where n is the DTIM interval defined in the AP. When the AP has buffered broadcast or multicast messages for associated wireless clients, it sends the next DTIM with a
DTIM Interval
value. This value decreases by '1' with each successive beacon. The AP sends broadcast and multicast messages immediately following the beacon where the DTIM value is '0.' To prevent a PSP-mode wireless client from sleeping through a DTIM notification, select a PSP mode value less than or equal to the DTIM value. PSP-mode wireless clients hear the beacons and awaken to receive the broadcast and multicast messages.
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A TIM is a compressed virtual bitmap identifying the AP associated wireless clients in PSP mode that have buffered directed messages. wireless clients issue a poll request when APs issue a TIM. A beacon with the broadcast-indicator bit set causes the wireless client to note wireless client of the beacons remaining before next DTIM. This ensures the wireless client turns on the receiver for the DTIM and the following
transmissions
DTIM Count
field value. The value informs the
BC/MC packet
.
HTTP, HTML Web
Server Support

Management Options

Hypertext Transfer Protocol
(HTTP) is the native language of the World Wide Web. The HTTP protocol makes requests from browsers to servers and responses from servers to browsers. This function provides the user with a Web-based format for configuration and firmware download.
Web pages are written in
Hypertext Markup Language
(HTML). HTML allows the user to create Web pages containing text, graphics, and pointers or links to other Web pages or elsewhere on the page or document. Pointers are known as
Uniform Resource Locators
(URLs). A URL is essentially the name of the Web page.
The URL consists of three parts:
Protocol (or Scheme)
1
Fully Qualified Domain Name (FQDN), the machine where the page is located
2
Local name that identifies the page (usually the HTML file name)
3
The HTML language describes how to format the document, indication which fonts to use, much like a copy editor describes which fonts to use, such as the location, color, header size and text.
Managing AirConnect includes viewing network statistics and setting configuration options. Statistics track the network activity of associated wireless clients and data transfers on the AP interfaces. Configuration involves, among other things, setting system operating parameters and filters used in bridging.
The AP requires one of the following to perform a custom installation or maintain the AirConnect network:
Simple Network Management Protocol
Wired or wireless LAN workstation with a telnet client
Terminal or PC with RS-232 connection and access to ANSI emulation
(SNMP)
Changing one AP does not affect the configuration of other APs on the network. Make configuration changes to APs individually. Each AP requires an individual IP address.
Theory of Operation 29
Programmable SNMP Trap Support
The SNMP protocol defines the method for obtaining information about networks operating characteristics and changing router and gateway parameters. The SNMP protocol consists of three elements:
Management stations
Management information
Management protocol
(MIB)
Nodes can perform as hosts, routers, bridges or other devices that can communicate status information. An
SNMP Agent
is a node that runs the SNMP management process to systematically monitor and manage the network. The management station performs network management by running application management software.
An
SNMP trap
is an alert to all configured management stations of some significant event that occurred on the network. The management station queries all stations for details of each specific event, including what, when and where the event took place and the current status of the node or network. The format or structure is defined in the SNMP protocol. The MIB defines what and who monitors the variables.
Using SNMP
The AP includes
SNMP agent
versions accessible through an SNMP manager application (HP Open View or Cabletron Spectrum MIB browser). The SNMP agent supports SNMP versions 1 and 2, MIB II, 802.11 MIB and one proprietary
Management Information Base
(MIB). The SNMP agent supports read-write,
3Com
read-only or disabled modes. The AP supports traps that return to the SNMP manager when certain events occur. The
Wireless LAN Installation and Utilities
disk
packaged with wireless clients contains the MIB.
Increased MIB Support
The MIB defines what the management station needs to understand and which objects the station manages. The MIB has ten categories defined with approximately 175 variables.
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Using the User Interface
The It provides statistical displays, AP configuration options, and firmware upgrades. Access to the UI requires one of the following:
Method Description
Telnet Client Gain access to the AP built-in Telnet server from any AP
Direct Serial Connection
Dial Up Access The dial-up access method requires a communication program
SNMP Via a MIB Browser
Web Browser Gain access to the AP built-in Web server from any AP interface
User Interface
(UI) is a text-based maintenance tool integrated into the AP.
interface including remote Ethernet connections.
Acts as a DTE device to connect directly to a DTE device with a null-modem serial cable. The direct serial access method requires a communication program with ANSI emulation.
with ANSI emulation on the remote terminal or PC. The terminal or PC dials to an AP with a modem connection. The AP supports connection to a Hayes-compatible 28,800-baud or faster modem.
Gain access to the AP SNMP function via a MIB Browser.
including remote Ethernet connections.
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