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3Com 3CRWE920G73 Quick Start Manual


Made by: 3Com
Type: Quick Start Guide
Category: Network Hardware
Pages: 13
Size: 0.38 MB


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Quick Start Guide


802.11g 54Mbps WLAN Building to Building 




Outdoor: 3CRWEASYG73 




















Published July 2005 

Quick Start guide version2.0.1 


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3Com Corporation 


Page 1 


1 Introduction 

Thank you for choosing the 3Com Corporation 802.11g 54Mbps Wireless LAN Building to Building Bridge.   

The outdoor version of 3Com 802.11g Wireless Bridge is ideal for rough outdoor environments and covering long 
distances, whereas the indoor version has a smaller profile to be unobtrusive and can be customized to the application 
with a variety of antenna selections. They can be configured as an inter-building wireless bridge with maximum 54Mbps 
transmission rate. 

This manual will give you a short introduction to the device(s) and will help you to start the Wireless Bridge step by step 
quickly. To install and manage this product, you will need a working knowledge of network structures, terms and concepts, 
and a professional level of experience in installation procedures for network operation systems under Microsoft Windows. 

In this Quick Start Guide you will find just the most basic information needed to install your Wireless Bridge, and get it up 
and running. For more detailed installation and configuration please consult the ‘‘3Com 802.11g 54Mbps Wireless 
Building to Building Bridge User’s Guide’’. 


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3Com Corporation 


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2 Package 


Please ensure that the package is complete before beginning with the installation. The package should include the 
following components:   


Indoor 802.11g 54Mbps Building to Building Bridge



Outdoor 802.11g 54Mbps Building to Building Bridge





3Com 802.11g Wireless indoor Bridge 


Mounting kit for wall or ceiling mount 


CD-ROM containing software and documentation 


Single-Port PoE Feeder.



Note: Indoor Bridge does not ship with an antenna. 


 or your reseller for antenna 




3Com 802.11g Wireless Outdoor Bridge 


Mounting kit for wall or mast mount 


CD-ROM containing software and documentation 


Single-Port PoE Feeder.



Lightning arrestor




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3Com Corporation 


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3 Hardware 


Installing the 3CRWE920G73 Indoor Wireless Bridge


On a flat surface 

1    Find a surface that is clear of debris. 

2    Set the bridge down on its four rubber feet. 


On a wall 

1    Use the mounting template as a guide to make two marks 7.40cm (2.91 inches) apart on the wall.


Use the vertical line on the template to ensure that the placement of the marks is plumb to the wall. 

2    Drill holes at the marks.


Use a 5-mm (3/16-inch) drill bit if using the provided screw anchors; use a 3-mm (1/8-inich) drill bit if using the screws 


3    Install the two flathead screws at the marks on the wall.


Leave the screw heads protruding 6-mm (1/4 inch) from the surface of the wall. 

4    Hang the bridge on the screws, using the mounting holes on the back of the bridge. 




On an acoustical ceiling


1    Attach the mounting bracket to the back of the bridge with two number 6 panhead screws. 

2    Align the T-rail grips with the ceiling T-rail, and adjust them so that they grip the T-rails securely. 

3    Tighten the screws on each T-rail grip. 

After installation, there may be some play in the fit of the T-rail grips if the T-rails are very narrow. If necessary, add a 
shim to achieve a secure grip. 




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3Com Corporation 


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Connect the antenna


1    Connect one end of the antenna cable to the antenna. 

2    Connect the free end of the antenna cable to the connection on the bridge.




Follow the instructions that come with the antenna and follow these general guidelines: 



For best performance, place the antenna using the mounting hardware provided with the antenna. Outdoor 
placement is especially important if the building is of metal construction or has metal siding. If necessary, you can 
mount an antenna inside a building; however, indoor placement reduces the antenna’s effective range.     



To ensure the physical safety of anyone near the antenna and to prevent damage to the bridge, follow the building 
codes for antenna installations in your area. 



Position the antenna so that there are minimal obstacles between it and any other antenna with which it will 
communicate. While maintaining a direct line of sight between antennas is not strictly necessary, such an 
arrangement helps to ensure a strong signal. Ensure that access is available for routing the antenna cable from the 
antenna to the bridge. When mounting an antenna indoors, best performance can be achieved by mounting the 
antenna near a window facing the opposite bridge. 



Make certain that the antenna and antenna mast are appropriately grounded. Proper grounding prevents injury or 
damage from lightning strikes. 



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3Com Corporation 


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Installing the 3CRWEASYG73 Outdoor Wireless Bridge


Mount the Unit to a Mast


Follow the instructions that come with the bridge mounting hardware and follow the general guidelines listed below. 


Mast should extend above 
bridge 1 meter (3 ft) 
Recommended Pole Diameter = 
2’’ --- 2.5’’ 
Maximum Pole Diameter =    3’’ 
Bridge may be installed to 
freestanding or roof mounted 



For best performance, place the antenna outdoors using the mounting hardware provided with the antenna. 
Placement is especially important if the building is of metal construction or has metal siding. If necessary, you can 
mount an antenna inside a building; however, indoor placement reduces the antenna’s effective range. 



To ensure the physical safety of anyone near the antenna and to prevent damage to the bridge, follow the building 
codes for antenna installations in your area. This is another good reason to make sure that only a professional 
performs the installation. 



Keep in mind that in order to comply with FCC radio-frequency radiation exposure guidelines, a minimum body to 
antenna distance of 2 meters (6 feet) must be maintained while operating this device. 



Ensure that access is available for routing the Ethernet cable from the bridge to the Ethernet connection inside. 



Make certain that the antenna mast is appropriately grounded. Proper grounding can prevent injury or damage from 
lightning strikes. 



After installing the bridge, the highest allowable power level is automatically set when country selection is 
configured. Adhering to this configuration ensures compliance with national laws. 



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3Com Corporation 


Page 6 


Align and Polarize the Units


For optimal performance, position the antenna so that there are minimal obstacles between it and any other antenna with 
which it will communicate. While maintaining a direct line of sight between antennas is not strictly necessary, such a 
configuration helps to ensure a strong signal. As mentioned earlier, this is not always possible in long distance 

Any two bridge units that are to communicate with each other must be set for the same polarization, either horizontally or 
vertically. If cross-polarization occurs, the link with either work poorly or not at all. Please refer to the ‘‘Polarization’’ 
section of the User Guide for further details. The following illustration shows proper alignment, orientation and 
polarization for optimal performance. 





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3Com Corporation 


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Antenna Specification


The following antennas and cables are available from 3Com Corporation: 


3CWE591 - 6/8dBi Dual-Band 

Omni directional Antenna



3CWE598 - 8/10dBi Dual-Band Panel 



3CWE495 13 dBi Sector-Panel 












3CWE596 - 18/20dBi Dual-Band 

Panel Antenna



Ultra Low Loss Coaxial 
Antenna Cables: 





3CWE580 (6 foot) 
3CWE581 (20 foot) 
3CWE582 (50 foot)












 Because of power level restrictions, use of the 3CWE495 13dBi and 3CWE596 18dBi antennas is not 

allowed in some countries.


The highest allowable power level is set automatically when you configure antenna selection after installing the bridge. 

To comply with power restrictions, identical antennas using 6-foot cable must be separated by at lease the minimum 
distances shown below: 



Minimum Distance for Full Throughput (approximate)


Antenna (dBi)






18 200 218 

13 50 55 

8 10 11 

4 2 2 



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3Com Corporation 


Page 8 


Connect to the Power Source and the Local Network 


Connect a twisted pair CAT5 Ethernet cable from 
the ’’To Hub/Switch’’ port of the PoE Adapter to a 
free port on the hub or switch within the local 

3CRWE920G73 Indoor Wireless Bridge 



3CRWEASYG73 Outdoor Wireless Bridge 



NOTE: 3Com recommends that you use a weatherproof and shielded CAT5 cable to help protect the Bridge and your 
network equipment from lightning and power surges. 

If the Bridge failed to power on or if it lost power, the automatic shutdown feature that is built into the PoE injector may have been 
activated to protect the Bridge from power surges. Try resetting the PoE injector. 
To reset the PoE injector: 



On the PoE injector, unplug the CAT5 cables that connect to the Bridge and the Switch. 



Unplug the power cord, and then wait for the PoE injector to automatically reset itself back to default. The reset process 
normally takes about five minutes. 



Reconnect the power and CAT5 cables to the PoE injector, and then wait for the Bridge to complete its startup process. This 
normally takes about one minute. 

To verify that you have successfully reconnected the Bridge to the network, use WIDMAN to search for the Bridge. It should appear in 
the list of detected network devices. If WIDMAN cannot detect the Bridge, please contact 3Com Customer Support. 


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3Com Corporation 


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LED Indicators


After the correct connection, the Power LED and the Ethernet link LED of the 3CRWE920G73 indoor bridge should light 
up. On the front of the Wireless Bridge you will find three LEDs 











Off: Power supply connection not available or broken   

On: Power supply connection OK   

WIRELESS activity LED 


Off: No activity 

Blinking: Sending and receiving data 



Off: No LAN connection available 

On: LAN connection OK 


4. Software 


Insert the installation CD-ROM delivered with the 3Com WLAN Building to Building Bridge into your CD-ROM drive   

The installation wizard starts automatically and will guide you through the rest of the installation process. If the installation 
wizard does not start automatically, run ‘‘setup.exe’’ from the root directory of the installation CD. Then choose to install 
the 3Com Wireless Infrastructure Device Manager (WIDMAN) utility for helping you find the Bridge and configure its IP 

The 3Com Installation CD contains the following tools and utilities: 

3Com Wireless Infrastructure Device Manager (WIDMAN) 

 an administration tool that helps you selects 3Com 

wireless LAN devices and launches their configurations in your Web browser. 

3Com 3CDaemon Server Tool ---

 a firmware upgrade tool that can act in four different capacities: 



As a TFTP Server, necessary for firmware upgrades, and backup and restore functions. Use this option if you do not 
have a TFTP server set up. 



As a SysLog Server, which is necessary to view SysLog messages. 



As an optional TFTP Client. 



As an optional FTP Server. 

[NOTE: It is recommended that you install the 3CDaemon Server tool if you do not already have a firmware tool for 
upgrades on your computer.]



To install one of the tools on your computer:


1  Turn on the computer; 

2    Insert the 3Com Installation CD in the CD-ROM drive; 

The setup menu appears. If it does not appear, you can start the setup menu from the Windows Start menu. For 
example: Start > Run > d:setup.exe . 

3    In the menu, click Tools and Utilities. 

4    In the next screen, click the tool you want to install. 

5    Follow the instructions on the screens to complete the installation. 

Reboot the computer if prompted to do so. 

6    Launch the tool from the Windows Start menu. 



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3Com Corporation 


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Find your New Wireless Bridge 

To find your new Wireless Bridge you will need to connect the Wireless Bridge to the same physical LAN network as your 
PC. By default, the Wireless Bridge will use DHCP Client mode to get an IP address from a DHCP Server. If your network 
does not have a DHCP server, the Bridge uses a default IP address of 169.254.X.Y, where the X and Y is the last two bytes 
of the MAC address in decimal value respectively. You can use that default IP address to configure the Wireless Bridge 
through a web browser directly. 

To find your new Wireless Bridge, open the 3Com Wireless Infrastructure Device Manager (WIDMAN) utility. On start up, 
the dialog box will look like the figure below: 


Click the ‘Refresh’ button and the 3Com Wireless Infrastructure Device Manager (WIDMAN) utility will begin to discover 
devices. After finding the new Wireless Bridge, it will list it in the list box. 

Choose the Wireless Bridge in the list box, and then click the ‘Configure…’ button. The web browser wills pop-up, and it 
will bring you to the WEB UI of the Wireless Bridge. 


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If 3Com Wireless Infrastructure Device Manager (WIDMAN) finds that your PC cannot connect to the Wireless Bridge by IP, 
it would pop-up a dialog requesting that you change the IP address of the device. Then the utility will prompt you to enter 
the password of the bridge.

 [Note: default password is ‘‘blank’’] 


If the password is correct, you will be able to configure it through the WEB UI.



[NOTE: It can take up to 60 seconds for the 3Com Building to Building Bridge to boot up after power has been 
connected. The Bridge will not appear in the WIDMAN utility unit boot up is complete. Click the REFRESH button 
occasionally until the Bridge appears.] 


The first time you configure the Wireless Bridge, you will see an initial Settings page. In this page, you will setup the 
username/password for administrator access. On international versions of the Bridge, you will select Country Settings on 
this page as well. 












For more detailed settings of the Wireless Bridge, please refer to ‘‘3Com 802.11g 54Mbps


Wireless Building to Building 

Bridge User’s Guide’’.


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6 Default 




Default Setting


Device Name 

3Com Building-to-Building Bridge 


For U.S. version, United States 


For non-U.S version, set by the user 

IP Network Setting 

Obtain IP address automatically 

IP Address 

Obtained automatically (with a DHCP server) 


169.254.X.Y (without a DHCP server) 

Subnet Mask 

Obtained automatically (with a DHCP server) (without a DHCP server) 

Default Gateway 

Obtained automatically (with a DHCP server) (without a DHCP server) 

DHCP Server 


DHCP Client 


Spanning Tree Protocol 


SNMP Read only Community 


SNMP Read Write Community 


TFTP Server 

Time Settings 


Wireless Network Name (SSID) 



2.4Ghz Mixed (Allow both 11b and 11g) 

Radio Channel 


Broadcast SSID 


Wireless Security 



7 Contents 



The CD-ROM which is enclosed in the package should include the following contents: 



3Com 802.11g 54Mbps Wireless LAN Building to Building Bridge User Guide 



MIB Directory 

Includes 3Com MIBs for Network Management usage 



Diagnostic Utility 



3Com 3CDaemon Server Tool 



3Com Wireless Infrastructure Device Manager 



Readme file 






Copyright © 2005 3Com Corporation. All rights reserved. 3Com and the 3Com logo are registered trademarks of 3Com 
Corporation. All other company and product names may be trademarks of the respective companies with which they are 


Published July 2005