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Cisco Aironet 802.11a/b/g Wireless LAN Client Adapters (CB21AG and PI21AG) Installation and Configuration Guide
OL-4211-03
Appendix E Configuring the Client Adapter through the Windows XP Operating System
Overview
Overview
This appendix provides instructions for minimally configuring the client adapter through the Microsoft
Wireless Configuration Manager in Windows XP (instead of through ADU) as well as for enabling the
security options that are available for use with this operating system. The “Overview of Security
Features” section below describes each of these options so that you can make an informed decision
before you begin the configuration process.
In addition, this appendix also provides basic information on using Windows XP to specify the networks
to which the client adapter associates and to view the current status of your client adapter.
Note If you require more information about configuring or using your client adapter with Windows XP, refer
to Microsoft’s documentation for Windows XP.
Overview of Security Features
When you use your client adapter with Windows XP, you can protect your data as it is transmitted
through your wireless network by encrypting it through the use of wired equivalent privacy (WEP)
encryption keys. With WEP encryption, the transmitting device encrypts each packet with a WEP key,
and the receiving device uses that same key to decrypt each packet.
The WEP keys used to encrypt and decrypt transmitted data can be statically associated with your
adapter or dynamically created as part of the EAP authentication process. The information in the “Static
WEP Keys” and “EAP (with Dynamic WEP Keys)” sections below can help you to decide which type
of WEP keys you want to use. Dynamic WEP keys with EAP offer a higher degree of security than static
WEP keys.
WEP keys, whether static or dynamic, are either 40 or 128 bits in length. 128-bit WEP keys offer a greater
level of security than 40-bit WEP keys.
Static WEP Keys
Each device within your wireless network can be assigned up to four static WEP keys. If a device
receives a packet that is not encrypted with the appropriate key (as the WEP keys of all devices that are
to communicate with each other must match), the device discards the packet and never delivers it to the
intended receiver.
You do not need to re-enter static WEP keys each time the client adapter is inserted or the Windows
device is rebooted because the keys are stored (in an encrypted format for security reasons) in the
registry of the Windows device. When the driver loads and reads the client adapter’s registry parameters,
it also finds the static WEP keys, unencrypts them, and stores them in volatile memory on the adapter.