3Com 3CRWE875075A, 3CRWE725075, 3CRWE825075A, 3CRWE885075A User Manual

Configuration Guide

WDS Bridging and Antenna Installation

3CRWE725075
3CRWE825075A
3CRWE875075A
3CRWE885075A

The 3Com Access Point 7250/8250/8750/8850 supports WDS Bridging, which provides a flexible way to
extend a wireless network. With WDS Bridging, you can increase your network to large, open locations
where pulling wire is cost-prohibitive, restricted, or physically impossible.

This guide explains how to configure a WDS link between two 3Com access points, and describes some
common installation scenarios for using WDS Bridging.

NOTE: For more information on the access points, including complete installation and
configuration instructions, see the Wireless
product CD in PDF format.

Understanding WDS Bridging Support

A Distribution System (DS) is a network (typically a wired network) that interconnects separate access
points into a single LAN. With WDS, the interconnection no longer needs to be physically wired.

uses the wireless medium to interconnect separate access points, thereby eliminating the cost and

WDS
inconvenience that may hinder wire installations.

A WDS link can be used in a simple point-to-point link, a complex point-to-multipoint link, or a
multilayer topology.

LAN Access Points User Guide included on the

Point-to-Point WDS Link

The following example shows a point-to-point WDS link configured between two access points.

Wireless Desktops Wireless Desktops

WDS Link

1

Point-to-Multipoint WDS Link

W

The following example shows point-to-multipoint WDS links configured between multiple access points.

Wireless Desktops

Point-to-Point WDS Link

ireless Desktops

WDS Link

Wireless Desktops

WDS Link

WDS Security and Spanning Tree Support

For added security, the AP 8250 supports AES encryption over the WDS link. Additionally, Spanning Tree
Protocol (STP) support prevents loops from being formed on the network. For more information on these
items, see the Wireless LAN Access Points User Guide.

Configuring WDS Bridging

WDS Bridging can be configured in numerous ways. This section describes two common installation
scenarios and the equipment required to complete the configurations:

 Remote building wireless access with the AP8850

 Remote building wireless access with the AP8250 and 802.11g Upgrade Kit

Configuration Guidelines

Before configuring the WDS settings, review the following guidelines:

 The WDS link can be set up between 3Com access points only.

 The pair of access points to be configured with a WDS link must be set to the same

radio channel and SSID, and the link must be set up between 802.11a radios or

802.11g radios (that is, 802.11a to 802.11a or 802.11g to 802.11g).

 The access points must be configured with security and standard access point settings

before configuring the WDS link(s).

 A Root Bridge can have a maximum of six Child Bridges assigned to it.

 A Child Bridge can have a maximum of five Child Bridges assigned to it.

Antenna Guidelines

The 802.11a and 802.11g radios can be used with the following antennas in a bridging application:

 802.11a radio: 3CWE591, 3CWE598, 3CWE596

 802.11g radio: 3CWE491, 3CWE495, 3CWE498

2

Safety Guidelines

Only a licensed electrician with expert knowledge of outdoor installation and weather proofing
techniques should perform an outdoor installation. Professional network personnel should oversee the
entire installation. The importance of this is paramount, for the sake of compliance with local building
codes, regulatory issues, and for the safety of people and equipment.

CAUTION: Review the safety notices on page 9 before continuing.

!

Remote Building Wireless Access with the AP8850

This installation scenario describes one layer of bridging with one Root-Bridge and one Child Bridge. This
scenario is common, for example, in schools or universities where students or professionals in remote
buildings need secure, high-bandwidth wireless access.

In this configuration, an AP 8850 is installed and connected to the wired LAN and at each of the desired
remote locations.

 The bridge at the center of the network is configured as the Root Bridge with an

omnidirectional antenna.

 The remote bridges are configured as Child Bridges and use directional antennas, which

are aimed at the Root Bridge antenna.

T
M

T
M

Child Bridge 1

Root Bridge

T
M

T
M

T
M

Child Bridge 2

The 802.11g radio at the remote location can be configured with any security configuration desired,
including open security or full WPA security with 802.1X client authentication and AES encryption.

3