Enterasys Networks 802.11 User Manual
ENJOY THE FREEDOM OF WIRELESS NETWORKING
802.11 Wireless Networking Guide
™
ENTERASYS.COM
P/N 9034042-08
NOTICE
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ARISING OUT OF OR RELATED TO THIS DOCUMENT, WEB SITE, OR THE INFORMATION CONTAINED IN
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OF, THE POSSIBILITY OF SUCH DAMAGES.
© June 2002 Entera sy s Netw orks
TM
All Rights Reserved.
Enterasys Networks, Inc.
500 Spaulding Turnpike
Portsmouth, NH 03801
Part Number: 9034042-08
Web Site: http://www.enterasys.com/wireless
Enterasys, Enterasys Networks, RoamAbout, and the RoamAbout logo are t ra demarks of Enterasys Networks, Inc.
Apple, the Apple logo, Macintosh, and PowerBook are trademarks or registered trademarks of Apple Computer, Inc.
IPX/SPX is a trademark of Novell, Inc.
LINUX is a trademark of Linus Torvalds.
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Contents
Preface
Intended Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Associated Documents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xii
Document Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Getting Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
1 Wireless Network Configurations
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
RoamAbout AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
RoamAbout PC Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Operating System Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Wireless Infrastructure Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Single AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Multiple APs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Wireless Client Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
LAN-to-LAN Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Point-to-Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Point-to-Multipoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
RoamAbout R2 Configuration Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
Workgroup Mode (both slots) Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
Workgroup Mode and LAN-to-LAN Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
Ad-Hoc Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15
Optional Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16
Vehicle-Mount Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16
Range Extender Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17
Outdoor Antenna Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-18
iii
Contents
2 Understanding Wireless Network Characteristics
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Wireless Network Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Access Point MAC Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
RoamAbout R2 MAC Addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Channel Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Transmit Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Auto Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Fixed Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Communications Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Signal Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Noise Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Data Throughput Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
AP Density and Roaming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
RTS/CTS Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
RTS Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Hidden Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
802.11 Power Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
RoamAbout AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
RoamAbout Client . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Network Operating System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
RoamAbout AP Secure Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Wired Equivalent Privacy (WEP) Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
Authentication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
802.1X Rapid Rekeying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
SNMP Community Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
Console Port Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
Network Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
Wireless Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
Beacons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
Message Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
Spanning Tree Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Using the Access Point 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Using the RoamAbout R2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
VLANs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
Access Point 2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
R2 Access Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
Network Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24
iv
Static and Dynamic VLANs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25
RoamAbout SNMP Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26
Access Point 2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26
RoamAbout R2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27
3 Designing and Implementing a Wireless Network
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Infrastructure Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Determining the Coverage Area and Supported Users. . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Selecting the Location for a Single AP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Selecting the Locations for Multiple APs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
RoamAbout R2 Mezzanine Special Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Using Multiple Wireless Infrastructure Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Using an Outdoor Antenna. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
LAN-to-LAN Network Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Ad-Hoc Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Wireless Network Hardware Installation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Wireless Infrastructure Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
LAN-to-LAN Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Ad-Hoc Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Contents
4 Wireless Network Tools
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
RoamAbout AP Manager. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Installing the RoamAbout AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Other SNMP Management Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
RoamAbout Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Telnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Web Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
RoamAbout Client Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
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Contents
5 Configuring the Wireless Network
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Configuring APs in an Infrastructure Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Required Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Wireless Parameters Used in an Infrastructure Network . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
Configuring APs in a Point-to-Point Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
Required Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
Wireless Parameters Used in a Point-to-Point Network. . . . . . . . . . . . . . . . . . . . . . . . . 5-9
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Configuring the AP for Point-to-Multipoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13
Required Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13
Wireless Parameters Used in a Point-to-Multipoint Network . . . . . . . . . . . . . . . . . . . 5-14
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Viewing Current AP Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Using the RoamAbout R2 Console. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Using the Access Point 2000 Console . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Modifying the IP Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21
Setting the Cabletron Discovery Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21
Modifying Wireless Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
Using AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Configuring for Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-24
Setting Secure Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-24
Setting Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-25
Configuring the Console Port for Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-28
AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-28
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Contents
RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-28
Access Point 2000 Console Port. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-28
Configuring the R2 for SNMPv1 or SNMPv2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-29
Configuring the AP for Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-30
RADIUS Management Authenticator (AP 2000 Only) . . . . . . . . . . . . . . . . . . . . . . . . 5-30
Configuring the AP for Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-32
Configuring for Rapid Rekeying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-37
Set Up Rapid Rekeying on the Clients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-38
Configuring for VLANs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-40
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-41
Using the RoamAbout R2 Web Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-42
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-42
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-42
Setting Spanning Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43
Using AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43
Filtering Traffic by Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-44
Filtering Traffic by Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-46
Checking the Configuration on Multiple APs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-47
Resetting the RoamAbout AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 48
Using the RoamAbout R2 Web Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-49
Configuring Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-50
6 Maintaining the Wireless Network
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Testing Radio Communications Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Using the RoamAbout Client Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
Optimizing RoamAbout AP Placement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Using the Client Utility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 -5
Using AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
Optimizing RoamAbout Outdoor Antenna Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Logging Measurement Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Checking the Client RoamAbout PC Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9
Monitoring the AP Using RMON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
Monitoring RADIUS Client Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
vii
Contents
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
Checking RoamAbout Product Version Numbers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Using AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Using the Client Utility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Upgrading the RoamAbout AP Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15
Using the AP Hardware Reset Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15
Replacing the PC Card in an AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16
7 Problem Solving
In This Chapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Using the AP LEDs to Determine the Problem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
RoamAbout R2 LEDs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
AP 2000 LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
AP (Classic) LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
Showing Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
Using the AP Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
Using the Access Point 2000 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
Using the RoamAbout R2 Console Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
Displaying Error Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18
RoamAbout PC Card LED Activity in a Client. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-19
Windows Does Not Detect the RoamAbout PC Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-21
Client Cannot Connect to the Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-21
Checking the Network Protocols on a Windows System . . . . . . . . . . . . . . . . . . . . . . . . . . 7-22
Device Conflict on a Windows System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-23
Windows NT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-23
Windows 95 or 98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-24
Changing the ISA Adapter Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-25
Setting SNMP Trap Addresses (Access Point Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-26
Setting Upline Dump (Access Point Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-27
A PC Card Information
Supported Frequency Sub-Bands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3
viii
B Connecting a Device to the Console Port
C ASCII to HEX Conversion
Glossary
Index
Contents
ix
A RoamAbout wireless network consists of RoamAbout wireless p rod ucts , such as the
RoamAbout R2 Wireless Access Platform, RoamAbout Access Point 2000, RoamAbout
PC Card, and other wireless products that use an 802.11 Direct Sequence (DS) compliant
radio.
This manual describes how to design, install, configure and maintain a RoamAbout
wireless network. It also describes how to troubleshoot problems that may arise during
installation or operation.
NOTE: AP refers to the Access Point and the RoamAbout R2 unless
NOTE
otherwise specified in this document.
Intended Audience
This manual is intended for the wireless network manager. You should have a basic
knowledge of Local Area Networks (LANs) and networking functions.
Preface
xi
Associated Documents
Associated Documents
You can download the documentation, drivers, and utilities from the RoamAbout Wireless
web site. Check the RoamAbout Wireless web site regularly for product upgrades:
http://www.enterasys.com/wireless
Component Information Location
RoamAbout AP Manager RoamAbout 802.11 Wireless Networking
Guide and online help
RoamAbout R2 Wireless Access
Platform
RoamAbout Access Point 2000 RoamAbout Access Point 2000 Hardware
RoamAbout 80 2.11 PC Card RoamAbout 802.11 PC Card Drivers and
RoamAbout 80 2.11 PC Card
Drivers
RoamAbout Client Utility RoamAbout 802.11 PC Card Drivers and
RoamAbout Outdoor Solution RoamAbout Outdoor Antenna Site
RoamAbout R2 Wireless Access Platform
Hardware Installation Guide and online help
Installation Guide and online help
Utilities Client CD-ROM Kit
RoamAbout 802.11 PC Card Installation
Guide
RoamAbout 802.11 PC Card Drivers and
Utilities CD-ROM Kit
RoamAbout 802.11 PC Card Drivers and
Utilities Setup and Installation Guide and
online hel p
Utilities CD-ROM Kit
RoamAbout 802.11 PC Card Drivers and
Utilities Setup and Installation Guide and
online hel p
Preparat ion and Ins t al lat i on Gui de
xii
RoamAbout ISA Adapter Card RoamAbout ISA Adapter Installation
RoamAbout PCI Adapter Card RoamAbout PCI Adapter Installation
Document Conventions
The following icons are used in this document:
Icon Meaning
CAUTION: Contains information essential to avoid
personal injury or damage to the equipment.
Document Conventions
NOTE
NOTE: Calls the reader’s att ention to any item of
information that may be of special importance.
xiii
Getting Help
Getting Help
For additional support related to this device or document, contact Enterasys Networks
using one of the following methods:
W or ld Wide Web: http://www.enterasys.com/wireless
Phone: North America: (603) 332-9400
Europe: 353 61 701 910
Asia: +800 8827-2878
Internet mail: support@enterasys.com
To send comments or suggestions concerning this document, contact the Enterasys
Networks Technical Writing Department via the following e-mail
address: TechWriting@enterasys.com
Make sure you include the document Part Number in the e-mail message.
Before calling Enterasys Networks, please have the following information ready:
• Your Enterasys Networks service contract number
• A description of the problem
xiv
• A description of any action(s) already taken to resolve the problem
• The serial and revision numbers of all involved Enterasys Networks products in the
network
• A description of your network environment (for example, layout, cable type)
• Network load and frame size at the time of trouble (if known)
• The device history (for example, have you returned the device before, is this a
recurring problem)
• Any previous Return Material Authorization (RMA) numbers
Chapter 1
Wireless Network Configurations
There are three basic RoamAbout wireless network configurations:
• One or more APs connecting wireless clients to a wired network, using the Workgroup
Bridge mode. A wireless client can be any co mpu ter with an 80 2.1 1 Direct-Seque nce
(DS) compliant radio card. This type of network is referred to as a wireless
infrastructure network.
• Two or more APs used as a wireless link connecting wired networks. This is called a
LAN-to-LAN configuration. There are two variations of the RoamAbout LAN-to-LAN
configurations:
— Point-to-Point which connects two wired networ ks, using the LAN-to-LAN
Endpoint Bridge mode.
— Point-to-Multipoint which can connect multiple wired networks, using the
LAN-to-LAN Multipoint Bridge mode.
• Wireless clients communicating among themselves without a connection to a wired
network. This is called a peer-to-peer or ad-hoc network.
In This Chapter
Information in this chapter is presented as follows:
Topic Page
RoamAbout AP 1-2
RoamAbout PC Card 1-4
Wireless Infrastructure Network 1-6
LAN-to-LAN Configuration 1-9
RoamAbout R2 Configuration Examples 1-13
Ad-Hoc Network 1-15
Optional Antennas 1-16
1-1
RoamAbout AP
RoamAbout AP
This guide addresses the different RoamAbout AP hardware platforms: RoamAbout
Access Point (sometimes referred to as Classic), RoamAbout Access Point 2000, and
RoamAbout R2 Wireless Access Platform. Unless otherwise specified, AP refers to all the
RoamAbout AP platforms.
The RoamAbout Access Point Classic is no longer available; however, a number of the
Access Point 2000 reference information and procedures apply to the Classic platform.
The RoamAbout Access Point 2000 is a wired to wireless bridge. One port connects to an
Ethernet LAN. The other port connects to a wireless network. The wireless connection is
provided by a RoamAbout 802.11 DS compliant PC Card.
The RoamAbout R2 is an expandable wireless access platform designed to support
existing, and future, radio technologies and networking requirements.
The RoamAbout AP provides the following basic bridging services. See Chapter 2 for
descriptions of wireless LAN, security and management features.
• Store-and-forward capability
The AP receives, checks, and transmits frames to other LANs, enabling the
configuration of extended LANs.
• Frame filtering based on address
1-2
Using the address database and the source and destination addresses from incoming
frames, the AP isolates traffic that does not need to be forwarded to, or should not be
allowed on, other LANs. This action reduces the total data traffic on an extended LAN
and thus increases bandwidth efficiency.
• Data Link layer relay
The AP operates at the Data Link layer of the Open System Interconnection (OSI)
model. Operation at this layer makes the AP transparent to the protocols that use the
LAN connectivity service. This protocol transparency is a key factor in the extended
LAN service.
RoamAbout AP
• Dynamic address learning
The forwarding and translating process module automatically adds new source
addresses to the address database while the AP is operating. This reverse learning of
the address and port association allows automatic network configuration without prior
downline loading of configuration data to the AP. Address learning is protocol and
management entity independent.
An Aging Timer determines how long an address remains in the database. The timer
measures the time since data was last addressed to or from a particular node. If the
timer lapses without any traffic, the node’s add ress is removed from the database. The
Aging Timer interval can be modified by a Network Management System.
• Workgroup Bridge mode
In Workgroup Bridge mode, the AP commun icates with wireless clients. The AP on ly
forwards packets to multicast addresses, broadcas t addresses, and known ad dresses on
the wireless LAN.
The RoamAbout Access Point 2000 learns addresses only from the wireless side of the
network. The default Aging Timer interval is 32 minutes.
The RoamAbout R2 learns addresses from both the wired and wireless side. The
default Aging Timer interval is approximately 7 minutes.
• LAN-to-LAN Endpoint Bridge mode
In a Point-to-Point configuration, both APs are configured as Endpoints.
In this mode, the AP filters packets based upon their destination address and forwards
all packets with unknown addresses.
• LAN-to-LAN Multipoint Bridge mode
This mode is used where multiple APs are configured as dedicated wireless links
between LANs in a Point-to-Multipoint configuration . One AP mu st be designated as
the Central AP. The Central AP can communi cate with up to six oth er APs configured
as Endpoints.
In this mode, the AP filters packets based upon their destination address and forwards
all packets with unknown addresses.
NOTE: You must purchase a valid activation key to enable Multipoint
NOTE
bridge mode. Contact your Enterasys Representative.
Refer to the Release Notes that shipped with your AP for a complete list of product features.
1-3
RoamAbout PC Card
RoamAbout PC Card
The RoamAbout PC Card is an IEEE 802.11 Direct Sequence (DS) compliant wireless
network interface card.
The RoamAbout PC Card functions like any standard wired Ethernet card; however, the
RoamAbout PC Card uses radio frequencies instead of a cable for the LAN connection.
When installed in a computer, the PC Card and computer are referred to as a RoamAbout
wireless client.
The RoamAbout PC Card fits into any PC card type II slot and includes the following
features:
• The ability to support desktop PCs, via one of the following adapters:
— RoamAbout ISA Adapter Card option, which allows installation in to computers
that do not have a PC card slot but do have an available ISA bus slot.
— RoamAbout PCI Adapter Card option, which allows installation into computers
that do not have a PC Card slot or an ISA bus slot. The PCI Adapter works with
Microsoft Windows PC99-compliant PCs (PCI-slot-only PCs) that have
BIOS-supported PCI 2.2 or higher.
• An 802.11 DS compliant radio.
1-4
• The ability to communicate with 802.11 DS compliant APs or other 802.11 clients.
• The RoamAbout Client Utility, which allows you to monitor the quality of wireless
communication.
• Support for Wi ndo ws 95, Windows 98, Windows NT, Window s 2000, Windows Me,
Windows XP, MS-DOS, Windows 3.x, Windows CE, Linux, and Apple PowerBook
computers. Refer to the RoamAbout 802.11 PC Card Drivers and Utilities Setup and
Installation Guide for more information.
• 802.11 power management.
• Wired Equivalent Privacy (WEP) security.
• Roaming, where the client can move from one AP to another in the same wireless
network without losing LAN connectivity.
• Roaming over multiple channels. The RoamAbout PC Card automatically uses the
same channel as the associated AP.
• The RoamAbout PC Card is also the means by which a RoamAbout AP communicates
with a wireless network. This manual considers an AP and its installed PC Card(s) as
one unit.
RoamAbout PC Card
Operating System Suppo rt
You can have clients with various ope rating syst ems in the same wireless network. Refer
to the RoamAbout 802.11 PC Card Drivers and Utilities Setup and Ins tall ati on Gui de for
setup and installation information. For the latest version of the RoamAbout drivers, see the
RoamAbout web site: http://www.enterasys.com/wireless.
You may need to install the appropriate networking protocols when installing the
RoamAbout PC Card in the computer. The most common protocols include TCP/IP and
NetBEUI.
1-5
Wireless Infrastructure Network
Wireless Infrastructure Network
In a wireless infrastructure network, wireless clients communicate with an AP to connect
to a wired LAN. A RoamAbout wireless infrastructure net work can support clients with
various operating syste ms.
The area where a client can communicate with the AP is called a cove rage area. To increase
the coverage area, you can add APs to the wireless network.
Single AP
A single AP supports a single wireless infrastructure network. Each wireless client must
communicate with the AP to connect to the wired network.
NOTE: The RoamAbout R2 with the Mezzanine option can support two
NOTE
separate wireless infrastructure netwo rks. Refer to “RoamAbout R2
Configuration Examples” on page 1-13.
You can have multiple wireless infrastructure networks, each with a single AP and different
wireless names. Each network is a separate entity. Clients cannot roam between networks.
Multiple APs
A wireless infrastructure network can consist of multiple APs. This extends the coverage
area of the wireless network. To allow roaming, each AP in th e wireless network mu st use
the same Wireless Network Name.
1-6
NOTE: The RoamAbout R2 with the Mezzanine option can effectively be
NOTE
configured as two APs supporting the same wireless infrastructure network.
Refer to “RoamAbout R2 Configuration Examples” on page 1-13.
In this configuration, the wireless network consists of cells. A cell is a single AP and its
wireless clients within a network of multiple APs.
Figure 1-1 shows two APs in the same wireless network.
Wireless Infrastructure Network
Figure 1-1: Cells Within a Wireless Infrastructure Network
Configuration
AP1
Workgroup
Mode
Coverage
Areas
AP2
Workgroup
Mode
Cell 1 Cell 2
Wireless
Client
To allow wireless clients to physically move within a wireless network, the coverage areas
should overlap. In Figure 1-1, Cell 1 and Cell 2 share overlapping areas of coverage. As a
wireless client moves from Cell 2 to Cell 1, the necessary infrastructure network
information is passed from AP2 to AP1 while maintaining LAN connectivity. The
capability of moving from one AP to another without losing the network connection is
called roaming.
When a wireless client (such as the laptop computer in Figure 1-1) approaches the outside
boundary of a coverage area, the client can sense that another AP using the same Wireless
Network Name is providing a better quality signal. The client then automatically switches
to the other AP. If the other AP is using a different channel, the client automatically
switches to that channel.
1-7
Wireless Infrastructure Network
Wireless Client Behavior
You can configure the wireless client to connect to a specific wireless network or the first
available wireless network.
If you configure the client to connect to a specific wireless network, the client establishes
a radio connection to the AP in the specified wireless network that provides the best
communications quality. APs in a different wireless network are ignored.
If you configure the client to connect to the first available wireless network (the Wireless
Network Name = ANY), the client establishes a radio connection to the AP that provides
the best communications quality. Be aware that if there are multiple wireless networks, the
client could connect to an AP that is not in the network you want to join.
In either configuration, the client automatically matches the radio channel used by the AP.
A wireless client configured to connect to any available network does not automatically
switch networks after it makes a connection to a wireless network; for example:
Your wireless client is configured to connect to the first available wireless network.
The first available network is called SouthSide. Once the connection is made, you
move your client out of range of SouthSide, but in range of another wireless network
called NorthSide. The wireless client loses the connection to SouthSide but does not
make the connection to NorthSide. To connect to NorthSide, you need to restart the
client. After the restart, the wireless client connects to NorthSide since it is the first
available wireless network.
1-8
LAN-to-LAN Configuration
You can connect separate LANs over a wireless link by configuring two or more
RoamAbout APs to communicate with each other. This is called a LAN-to-LAN
configuration.
There are two variations of the RoamAbout LAN-to-LAN configur ation:
• Point-to-Point, using the LAN-to-LAN Endpoint Bridge mode, which connects two
wired networks.
• Point-to-Multipoint, using the LAN-to-LAN Multipoint Brid ge m ode, which can
connect multiple wired networks.
Typically, the APs are configured with outdoor antennas. If you use an outdoor antenna,
you should have a professional antenna installation company perf orm the installation.
Contact your Enterasys sales representative or visit the RoamAbout web site,
www.enterasys.com/wireless, for more information about the outdoor antenna kits.
Point-to-Point
Figure 1-2 shows two APs, configured as LAN-to-LAN Endpoint Bridge mode, in
different buildings using an outdoor antenna to connect the LANs in those buildings. As
shown in the figure, both APs use a directional antenna. You can also configure the APs to
connect two LANs in the same building.
LAN-to-LAN Configuration
Figure 1-2: Point-to-Point Configuration
Endpoint
Mode
Endpoint
Mode
1-9
LAN-to-LAN Configuration
Point-to-Multipoint
You can connect wired LANs in different buildings using the LAN-to-LAN Multipoint
feature. At least one of the APs is configured as a Multipoint AP, called the Central AP.
The Central AP can communicate directly with up to six APs. The six APs are configur ed
as Endpoints, which can only communicate directly to the Central AP. The Central AP
allows the Endpoint APs to communicate with each other through the Central AP.
A Central AP uses an omni-directional antenna so that it can communicate with multiple
APs in different directions. The Endpoint APs usually use a directional antenna pointed at
the Central AP. The directional antenna allows you to increase the distance between APs.
There must be a clear line sight between antennas to avoid a reduction in the s ignal level.
NOTE: The RoamAbout R2 Mezzanine option (slot 2) does not support
NOTE
Configuration Examples
Figure 1-3 provides an example of a Central AP with six Endpoint APs. The Endpoint APs
can only communicate with the Central AP and not directly with each other. Therefore, the
Central AP should be connected to the main wired LAN.
LAN-to-LAN Multipoint. This means that an R2 can use its Slot 2 radio to
participate as an Endpoint AP in a Point-to-Multipoint configuration, but
cannot use its Slot 2 radio to act as a Central AP.
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Figure 1-3: Point-to-Multipoint Configuration
Endpoint Mode
Endpoint Mode
Omni-Directional
Antenna
Multipoint Mode (Central AP)
Endpoint Mode
Endpoint Mode
Endpoint Mode
Endpoint Mode
LAN-to-LAN Configuration
Omni-Directional
Antenna
A5
Endpoint Mode
A3
Endpoint Mode
A1
Endpoint Mode
Building A
Multipoint Mode (Central AP)
A2
Endpoint Mode
A4
Endpoint Mode
Building B
Multipoint Mode
(Central AP)
A4
Endpoint Mode
B5
Endpoint Mode
B2
Endpoint Mode
B3
Endpoint Mode
B4
Endpoint Mode
Building B
Multipoint Mode
(Central AP)
B1
Endpoint Mode
A4
Endpoint Mode
Building B
Multipoint Mode
(Central AP)
Figure 1-4 provides an example of two Central APs in the same Point-to-Multipoint
configuration. In this configuration, six APs are configured to communicate with the same
Central AP. You can configure one or more of those six APs as a Central AP to
communicate with up to five additional APs. If using an Access Point 2000, this
configuration requires the Wireless Relay parameter to be enabled.
Figure 1-4: Point-to-Multipoint-to-Multipoint Configuration
Area 1
A1
Endpoint Mode
Omni-Directional
Antenna
Building A
Multipoint Mode (Central AP)
A2
Endpoint Mode
A4
A3
Endpoint Mode
Endpoint Mode
Area 2
B1
Endpoint Mode
A5
Endpoint Mode
Building B
Multipoint Mode
(Central AP)
B5
Endpoint Mode
B4
Endpoint Mode
B2
B3
Endpoint Mode
Endpoint Mode
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LAN-to-LAN Configuration
In Figure 1-4, Building A is the Central AP for Buildings A1 through A5 and Building
B. However, Building B is also the Central AP for Build ing A and Buildings B1
through B5. You could expand this one further by making Building B3 a Central AP
for five other buildings, although adding additional hops may decrease network
performance.
To avoid bridging problems, d o not conf igure an AP as an Endpoint fo r more than one
Central AP. In Figure1-4, you would not configure Building B1 as an Endpoint to
communicate directly to Building A.
Preventing Network Loops
It is important to avoid Point-to-Multipoint configurations that will cause bridge loops. A
bridge loop occurs when two parallel network paths are created between any two LANs,
causing packets to be continuously regenerated through both parallel paths. This situation
eventually renders the network unusable due to the excessive traff ic that is being generated
by the loop. The AP Spanning Tr ee function corrects t his type of problem by s hutting down
the port and possibly shutting down a segment of the network.
Figure 1-5 provides examples of configurations that cause Network Loops.
Figure 1-5: Network Loops
Building B
Multipoint Mode
Building B
Endpoint Mode
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Building A
Multipoint Mode
Building C
Multipoint Mode
Building A
Multipoint Mode
(Central AP)
Wired or Fiber Link
Building C
Endpoint Mode
RoamAbout R2 Configuration Examples
RoamAbout R2 Configuration Examples
This section provides co nfigur ation ex amples us ing the RoamA bout R 2 (with t he two- slot
option).
Restrictions
• The RoamAbout R2 slot 2 does not support LAN-to-LAN Multipoint.
• If two 802.11b PC Cards are installed in the RoamAbout R2 Wireless Access Platform,
one of the PC Cards must be connected to the Range Extender Antenna to prevent rad io
interference between the two cards. The antenna mus t be placed at least two f eet away
from the RoamAbout R2.
• The 802.11 PC Cards must be at least 5 channels apart from each other.
Workgroup Mode (both slots) Example
Figure 1-6 shows a RoamAbout R2 with both slots configured in Workgroup mode.
Figure 1-6: Workgroup Configuration
R2 With Mezzanine Option
Slot 2
Workgroup
Mode
Slot 1
Workgroup
Mode
WNG_21
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RoamAbout R2 Configuration Examples
Workgroup Mode and LAN-to-LAN Example
Figure1-7 shows two RoamAbout R2 s in different buil dings using an outdo or directional
antenna to connect the LANs in those buildings. Each RoamAbout R2 contains two radio
slots; one slot configured in Workgroup mode, and one slot configured in LAN-to-LAN
Endpoint Bridge mode.
In addition, a RoamAbout R2 can be config ured for mu ltipoint mode (slot 1 o nly), connect
to an omni-directional antenna, and connect to other APs.
Figure 1-7: Workgroup and LAN-to-LAN Endpoint Configuration
Slot 2
Workgroup
Mode
R2
Slot 1
Endpoint
Mode
Slot 2
Endpoint
Mode
R2
Slot 1
Workgroup
Mode
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