This document provides information on the most frequently asked
questions (FAQ) asked about Cisco Aironet Client Adapters used with Microsoft
Windows operating systems.
Technical Tips Conventions for more information on document
Where can I find the latest utilities, drivers, and firmware for my
A. Cisco Aironet equipment operates best when all components are loaded
with the most current version of the software. You can download the latest
software and drivers at
registered customers only)
At what frequency does a client card
A. The 802.11b and 802.11g standards define a total of 14 frequency
channels in the 2.4 GHz band. The 802.11a standard defines 12 channels in the 5
GHz band for UNII-1 communications.
In 802.11b/g installations, channels 1 through 11 can be used within
the United States. These are public frequencies and are unlicensed by the
Federal Communications Commission (FCC). Most of Europe can use channels 1
through 13. Channels 1 through 14 are allowed in Japan.
In 802.11a access point/client installations, channels 36, 40, 44, 48,
52, 56, 60 and 64 can be used in the United States. These are public UNII-1
frequencies and are unlicensed by the FCC. Most of Europe can use these same
channels. Channels 34, 38, 42 and 46 are allowed in Japan.
What is the typical range for a client card?
A. The typical range for a client card depends on many factors. Among them
are data rate (bandwidth) desired, antenna type and cable length (where
applicable), and the device that sends and receives the transmission. In an
optimal installation, the range can be up to 300 feet.
Due to the reduced maximum allowable transmit power on the 802.11a
band, the range for 802.11a installations is less.
The best estimates of performance and range for a given install site
come from a presales site survey. Contact your Cisco Systems Engineer (SE),
Cisco account team or Cisco authorized wireless reseller for assistance in the
coordination of a site survey by a qualified survey partner.
Are the 340 and 350 Series products
A. Yes. The major difference between the two product lines is the power of
the radio. The 350 Series has the stronger radio at 100 milliwatts. In a mixed
installation, the shorter range of the 340 Series prevails. Both series operate
only in the 802.11b frequency band.
The CB20A Card operates in the 802.11a band, and the CB21AG or PI21AG
Cards can operate in any of the three bands (802.11a, b or g), but only in one
band at a time.
What is Wireless Zero Configuration (WZC)?
A. The WZC service is built into the Windows XP operating system. The
Microsoft WZC service is designed to dynamically select the wireless network to
which it will attempt a connection, based either on your preferences or on
default settings. This includes the automatic selection and connection to a
more preferable wireless network when it becomes available.
The WZC service is not installed by default during a Windows XP
Complete these steps in order to install the WZC service on your
Click Start, then click Control
In the Control Panel window under Pick a Category, double-click the
Network and Internet Connections icon.
In the Network and Internet Connections window under or pick a
Control Panel icon, double-click the Network Connections
In the Network Connections window under LAN or High Speed Internet,
click to select the Local Area Connection icon.
On the menu bar, click File.
On the File menu, click Properties.
In the Local Area Connections Properties window, on the General
tab, click Install.
In the Select Network Component Type window, in the type of
network... box, click to select the Service icon.
In the Select Network Service window, click Have
In the Install From Disk window, click Browse....
In the Locate File window, browse to the C:WindowsInf folder (this
is a hidden folder).
Click to select NETWZC.INF.
In the Install From Disk window, click
In the Select Network Service window, in the Network Service box,
click to select Wireless Zero
At this point, you need to reboot your PC. With that completed, you
should find that the WZC service has been successfully installed on your
system, and you should now have access to the Windows Network tab.
Note: If you do not see the Wireless Network tab when you go back into
the Network Properties page, then the problem might be that the service did not
Complete these steps in order to start the service:
Open Administrative Tools in the Control Panel
and select Services.
Scroll down to Wireless Zero Configuration, right-click on it and
The service is now enabled. If the USB adapter had been
successfully configured, then the Wireless Network tab will be visible under
New notebooks that are equipped with wireless network adapters
from the manufacturer usually have WZC pre-installed.
In order to make use of the WZC service, you must use a
compatible wireless network adapter, such as a Cisco adapter. The wireless
network adapter scans for available wireless networks and passes the network
names (also known as Service Set Identifiers or SSIDs) to the WZC
Zero - Auto configuration from Microsoft explains how to configure the
Note: However, make sure that you do not run a third party wireless
client utility, such as Cisco's Aironet Desktop Utility (ADU), as well as WZC
service simultaneously on your computer. This can lead to an inconsistent
client connectivity issue. In such cases, you can disable the WZC service on
Complete these steps in order to disable WZC on your
Click Start, then click Control
Click Performance and Maintenance, click
Administrative Tools, and then click
Double-click the Wireless Zero Configuration
On the General tab, click
In the Startup type list, click Disabled, then
The WZC is now disabled and does not reload when you restart your
Can I run two computers together without an access
A. From the Aironet Client Utility (ACU) or Aironet Desktop Utility (ADU),
configure the clients to run in ad-hoc mode. This is only a
peer-to-peer connection. One PC becomes the parent, while the other becomes the
The CB20A does not support ad-hoc mode. However, the CB21AG or PI21AG
does, but only in the 802.11b mode.
How do I make a client card work with a non-Cisco access
A. The access point, not the client, controls interoperability. Make sure
that the access point does not use any proprietary extensions or require
firmware specific to the products of the manufacturer. Also, ensure that the
access point is 802.11-compliant for the frequency band desired.
I am working a new install of WLC4402 and have found that the wireless
handheld devices work fine. However, if they go into hybernation,
authentication is lost and they have to reauthenticate all over again. Is this
an expected behavior?
A. It is normal behavior for any client (laptop/scanner/pda) to
reauthenticate after power-save mode if it had been asleep for more than the
WLAN session timeout and User Idle timeout periods.
Can a Windows Zero Configuration (WZC) supplicant support fast roaming
with an access point (AP)?
A. No, in order for a wireless client or a supplicant to support fast
roaming, it must support Cisco Centralized Key Management (CCKM). A WZC does
not support CCKM.
When you use CCKM, authenticated client devices can roam from one AP to
another without any perceptible delay during reassociation. An AP on your
network provides wireless domain services (WDS) and creates a cache of security
credentials for CCKM-enabled client devices on the subnet. The WDS AP cache of
credentials dramatically reduces the time required for reassociation when a
CCKM-enabled client device roams to a new AP.
Can I remove the PC Memory Card International Association (PCMCIA) card
radio module from an Aironet PCI client adapter and use it as a PCMCIA client
A. No, this is not supported in any version of the hardware. Because the
radio card is set to a different I/O mode, the operating system does not
recognize the card. There is no known method to bypass this problem.
What is the Cisco Compatible Extensions (CCX)
A. The CCX program ensures the widespread availability of client devices
that are interoperable with a Cisco Wireless LAN (WLAN) infrastructure and take
advantage of Cisco innovations for enhanced security, mobility, quality of
service, and network management. Cisco does not sell or support Cisco
Compatible client devices, but the device manufacturers do. Refer to
Compatible Client Devices and
Compatible Extensions - Versions and Features for information on Cisco
How do I know if a client device is interoperable with a Cisco Wireless
LAN (WLAN) infrastructure and supports the latest WLAN standards and Cisco
A. Look for the Cisco Compatible logo, which is earned through the Cisco
Compatible Extensions (CCX) program for WLAN client devices. In the program,
Cisco licenses a specification with the latest WLAN standards and Cisco
innovations. A program participant, such as the maker of a WLAN client adapter
or client device, implements support for all features and then submits the
product to an independent lab for rigorous testing. The device can earn the
right to be called Cisco Compatible only if the device passes all the tests.
Refer to Cisco
Compatible Extensions Program Brochure for more information on the CCX
My 350 adapter uses Cisco Centralized Key Management (CCKM) to associate.
Why does the adapter not use fast roaming?
A. The 350 cards use fast roaming if they use Lightweight Extensible
Authentication Protocol (LEAP) or Extensible Authentication Protocol (EAP)-FAST
with CCKM. Although the 350 associates with other EAP types through CCKM, the
fast roaming feature is not supported with those EAP types.
How do I configure the Aironet Client Utility (ACU) or Aironet Desktop
Utility (ADU) so that the radio icon appears in the system tray
A. When you install the client driver and utilities for a Cisco Aironet
340, 350, and CB20A Wireless LAN Client Adapters, a utility called Aironet
Client Monitor (ACM) also is installed. ACM is an optional application that
provides a small subset of the features available through ACU. Specifically,
ACM enables you to access status information about your client adapter and
perform basic tasks. ACM is accessible from an icon in the Windows system tray,
which makes ACM easily accessible and convenient to use. Refer to
the Aironet Client Monitor (ACM) for information on ACM and the
For Cisco Aironet 802.11a/b/g Wireless LAN Client Adapters (CB21AG and
PI21AG), a utility called Aironet System Tray utility (ASTU) is installed with
the other client utilities. ASTU is an optional application that provides a
small subset of the features available through ADU. Specifically, ASTU enables
you to access status information about your client adapter and perform basic
tasks. ASTU is accessible from an icon in the Windows system tray, which makes
ASTU easily accessible and convenient to use. The ASTU icon appears only if a
client adapter is installed into your computer and you have not disabled ASTU.
the Aironet System Tray Utility (ASTU) for more information on ASTU and
the features supported
Note: Sometimes, you need to select the utilities that you want to install
during the client software installation.
How many profiles can I create with the help of the Aironet Desktop
A. The ADU profile manager feature enables you to create and manage up to
16 profiles or saved configurations for your client adapter. When you try to
add more than 16 profiles, this message appears:
These profiles enable you to use your client adapter in different
locations, each of which requires different configuration settings. For
example, you can set up profiles to use your client adapter at the office, at
home, and in public areas such as airports. After you create the profiles, you
can easily switch between the profiles without a need to reconfigure your
client adapter each time you enter a new location.
Profiles reside in the registry. You lose any saved profiles if you
uninstall the software on the client adapter. In order to prevent the loss of
your profiles, Cisco recommends that you back up your profiles through the
import/export feature in Profile Manager.
Rather than attempt to reauthenticate when an Extensible Authentication
Protocol (EAP)-FAST authentication fails with one profile, can I configure
Aironet Desktop Utility (ADU) in such a way that it automatically moves to the
A. No, this cannot be accomplished with ADU profiles. You can configure
mulitple Service Set Identifiers (SSIDs) on the access point so that the
clients with different SSIDs can connect to the access point.
Is there a way to configure the Request To Send (RTS) and Clear To Send
(CTS) values with Aironet Desktop Utility (ADU) and CB21AG? This was possible
with Aironet Client Utility (ACU) and 350 cards. If there is not a way, then
what are the default values used by the client
A. The default value of the RTS threshold is 2346 in CB21AG. This is the
max. There is no such threshold for CTS because it is sent as a response to
incoming CTS. You can add a key in the driver hive registry in order to adjust
The RTS threshold equals your desired value.
This registry key that manipulates the RTS threshold value is provided
for Wi-Fi and other tests. Cisco recommends that you do not change this value
for general deployment because it can interfere with the rate adaptation
Can I configure Wi-Fi Protected Access-Pre-Shared Key (WPA-PSK) with the
help of the Aironet Client Utility (ACU)?
A. WPA provides a PSK version that is intended for use in small office,
home office (SOHO) or home wireless networks. Cisco ACU does not support
WPA-PSK. The Wireless Zero Configuration utility from Microsoft Windows
supports WPA-PSK for most wireless cards.
In WLC v4.1 (and later), do the client roaming parameters available from
the Wireless > 802.11x > Client Roaming page apply only to CCXv4 clients
(i.e., "directed roaming")? Do these parameters have any impact on non-CCXv4
A. Directed roaming is supported in CCXv4 and later. Cisco does not really
do directed roaming (the controller does not tell client to roam to a specific
access point) but does send these parameters to clients for clients to make
roaming decisions. These are only for CCXv4 and later clients. This will not
affect clients which have a CCX version earlier than 4.
Association and IP Addressing
The access point has an entry in the association table for my PC Memory
Card International Association (PCMCIA) card, but I cannot get a dynamic IP
address. What is the problem?
A. The most common cause of this behavior is the inability of the PC to
communicate with the card through the PCMCIA socket. Check the driver for your
PC card socket. If the driver is a CardBus driver, check whether it is 32-bit
only. The Cisco Aironet card requires 16-bit access. If the driver for the
socket only works in 32-bit mode, you must contact the manufacturer of the
computer for a 16-bit version. If the manufacturer cannot provide you with one,
there are third-party PCMCIA card and socket service manufacturers who sell
products that support 16-bit access.
The CB20A and CB21AG Cards are CardBus compliant, and only work with
hardware sockets and drivers that supply 32-bit access. The PI21AG is a PCI
card, so other problems can contribute.
What devices can associate with a client card?
Refer to the
Aironet Hardware Association Matrix for more details.
How many clients can associate to an access
A. An access point has the physical capacity to handle 2,048 MAC
addresses. However, the access point is a shared medium and acts as a wireless
hub. Therefore, a large number of users on an individual access point degrades
The best estimates of potential client population for a given install
site come from a presales site survey. Contact your Cisco Systems Engineer
(SE), Cisco account team or Cisco authorized wireless reseller for assistance
in the coordination of a site survey by a qualified survey partner.
Why does my client card not associate to the closest access
A. If you have multiple access points in your wireless topology, your
client maintains an association with the access point with which the client
originally associated. The association remains until the client loses keepalive
beacons from that access point. The client then seeks out another access point
and attempts to associate to that access point, if the client has sufficient
rights and authorization on the new access point.
Make sure that available configured data rates match between a given
client and the access point desired. An auto setting on the client card does
not automatically match everything, but allows the client card to rate shift
among available rates that the access point advertises.
Where can I find help to install my client
A. Refer to
Aironet Wireless LAN Client Adapters Installation and Configuration Guide for
Aironet 802.11a/b/g Wireless LAN Client Adapters Installation and Configuration
Guide. Refer to the
Devices Technical Support page for additional information, which
includes installation-related documents.
How do I update the software for my Windows
A. There are three pieces of client software:
The radio firmware on the card
The client driver for the operating system
The Aironet Client Utility (ACU)
The radio firmware resides on the client device, and in the case of the
PC card, is removed when the card is removed.
The client driver is the software that manages interactions between
Windows (or another operating system) and the hardware.
The ACU is a utility to manage the card and the radio.
These three pieces of software have different functions, but work
together to provide wireless connectivity to your client. You must always use
the most recent versions of the software available. These three pieces of
software have been combined into the Cisco Aironet Client Adapter Installation
Wizard for Windows available at
registered customers only)
How do I install the PC card drivers on my Windows NT 4.0-based
A. Windows NT 4.0 does not support Plug-and-Play. Therefore, check the
available Interrupt Request (IRQ) and I/O ports. In order to do this, choose
Programs > Administrative Tools > Windows NT
Try IRQ port 10 and I/O port 100 first. Then choose Control
Panel > Network > Adapter > Add.
Pick the right driver from the installation diskette. In NT, look at
the interrupt settings I/O base 64 k contiguous I/O block. Do not select
obvious I/O blocks.
In order to find out which interrupts are in use, choose
Programs > Administrative Tools > NT Diagnostics, then
click the Resource tab.
This information is what NT reports, and is not set in the registry. Do
not select obvious I/O bases, such as I/O bases, that sound cards use. NT then
copies and binds the files.
How do I remove the PC card drivers on my Windows-based
A. In Windows 95 and Windows ME, remove these files:
In Windows 98, remove the files listed for Windows 95 and Windows ME
and this additional file:
In Windows 2000, make sure the card is inserted, then remove these
The Aironet card copies protocols from other network cards.
Current versions of the Aironet Client Adapter software put an entry in
the Add/Remove Programs panel of Windows.
After I insert my PCI card and boot my PC, the Cisco Aironet installation
software indicates that the card is not installed. What is the
A. Sometimes when a new PCI card is installed in a PC, the BIOS/CMOS does
not reread the PCI bus and recognize that a new card has been inserted. Reboot
the computer and enter your CMOS setup program. Some computers require you to
press Delete, F2, F10, or
other keys. Some computers require you to boot with a special boot utility
disk. Have the CMOS reset configuration data or refresh hardware configuration.
This wording can be different and depends on the manufacturer of the BIOS. If
there is no option of this nature, change the date/time, or some other minor
BIOS setting. Then, save the changes and exit.
The fact is that something in CMOS changed must trigger a re-read of
the PCI bus and make sure the hardware recognizes the PCI card so that Windows
also recognizes the card. If you are unable to get the BIOS to see the card at
this level, contact technical support for assistance on your PC.
Do I require Windows 98 driver for my AIR-PI21AG-A-K9 802.11 a/b/g PCI
adapter? I cannot find the driver in the Wireless Downloads page.
A. The Windows 98 platform does not support the AIR-CB21AG cards and
AIR-PI21AG cards. These cards are developed only for Windows XP and Windows
2000 platforms. You can use the 350 Series Client Cards with 802.11b radio or
the Cisco Aironet 5 GHz Wireless LAN Client Adapter (CB20A). The Windows 98
platform supports these client cards. Drivers for these cards are available at
registered customers only)
What are the Cisco Client Adapters and Utilities supported on Windows
A. Currently,Cisco Aironet 802.11a/b/g Cardbus Wireless LAN Client Adapter
(CB21AG) and Cisco Aironet 802.11 a/b/g PCI Wireless LAN Client adapter
(PI21AG) are supported on Windows Vista. Refer to
Notes for Cisco Aironet 802.11a/b/g Client Adapters (CB21AG and PI21AG) for
Windows Vista 1.0 for more information about Vista support on Wireless
Cisco Aironet Desktop Utility (ADU) and Cisco Aironet Client Utility
are not supported on Windows Vista.
How do I set the client card back to the factory default
A. Launch the Aironet Client Utility (ACU) or Aironet Desktop Utility
(ADU) and click Commands, then click Edit
Properties. On each tab, click Defaults.
Do I need special hardware to support
A. The specific hardware model determines the level of encryption for the
The 342 and 352 models support both 40- and 128-bit
The 341 and 351 models support only 40-bit
The CB20A and CB21AG models support both 40- and 128-bit
The CB21AG model supports AES encryption, as well.
PI21AG supports for static and dynamic IEEE 802.11 WEP keys of 40 and
How do I secure the data across the radio link of a client
A. Enable Wired Equivalent Privacy (WEP) to encrypt packets sent across a
radio link. Refer to
Equivalent Privacy (WEP) on Aironet Access Points and Bridges Configuration
Example for more information.
Miscellaneous Problems and Errors
When my PC card passes traffic, the speakers in my laptop buzz. What is
A. This problem comes from inadequate shielding around the PCMCIA socket.
The radio energy of the card that passes traffic leaks over into the speakers
(because the energy is not sufficiently contained in the card socket) and
manifests as a buzz in the speakers. Therefore, this buzz is not a problem with
the card, but with the socket. Resolution must come from the laptop
manufacturer that chose not to shield the socket.
What are possible sources of interference for the radio frequency (RF)
link of my client card?
A. Interference can come from a number of sources, including 2.4 GHz
cordless phones, improperly shielded microwave ovens, and wireless equipment
manufactured by other companies. Police radar, electrical motors, and moving
metal parts of machinery can also cause interference. Refer to
Problems Affecting Radio Frequency Communication for more
Do autonomous access points (APs) support load balancing with all
Wireless client adapters?
A. Autonomous APs support load balancing only with Cisco 350 Wireless
Cards with Aironet extensions enabled. Because this is not included in the
Cisco Compatible Extensions (CCX) program, it does not work with any other
How do you turn on logging in Windows Zero Config (WZC) in Windows
A. On the client, turn on the EAPOL and RASTLS logs with these
In order to disable the logs, run the same commands, but replace
enable with disable. For XP, all logs are
located in %systemroot%\windows\tracing.
I configured a Windows Zero Config (WZC) supplicant with a SSID name. I
have SSID broadcast disabled in the access point (AP). It is configured for
static Wired Equivalent Privacy (WEP). Association with the AP is fine when
this SSID is used. However, once I disconnect the wireless connection from the
wireless network list (windows), it is removed from the network list. Why is
A. The WZC supplicant configuration needs to have the broadcast SSID
enabled for this to work as expected. If broadcast SSID is not enabled, the
utility runs into issues of the network disappearing from the list.
I configured two networks with SSID broadcast enabled in the access point
(AP). However, I can only see one network in the wireless network list
(windows). Is this normal and is there any workaround to see
A. If you use Multiple Basic Service Set Identifier (MBSSID) on the AP,
then the AP uses an offset MAC address to broadcast both SSIDs. Because any
broadcast SSID requires the MAC address of the AP, without MBSSID enabled, you
will only see one.
When a client comes back from sleep mode, the client does not get
reauthenticated automatically to the access point (AP). It requires the entire
authenticating process to be restarted. Is this
A. It is normal that a client adapter has problems re-authenticating to
the AP once it comes back from sleep mode. The AP has an inactivity timeout.
Therefore, when an adapter goes in to sleep mode the AP de-authenticates the
client. When the client resumes the session, it keeps the status of
authenticated. Because of this, it does not re-send the probe request in order
to start the whole process over again. This is why if they boot or restart the
authentication process, the client is able to authenticate.
What does error message mean: "Packet to client xxxx
reached max retries, removing the
A. The Packet to client xxxx reached max retries, removing
the client error message means that the AP disassociates the
client because the client did not respond to max keep-alive messages sent by
the AP. This can be an indication of a bad RF. Configure this command on the AP
in order to eliminate this issue and to enable the client to not lose the
packet retries 128 drop-packet
The increase of packet re-tries to 128 with the drop-packet option is a
workaround for the bad RF problem. Refer to
the Maximum Data Retries for more information on this command.
Is it possible to dynamically manage client bandwidth via the RADIUS
server and BBSM?
A. Yes. This can be achieved by using the Cisco Building Broadband Service
Manager (BBSM) with RADIUS server.
Cisco BBSM provides public and guest Internet access management
features and functionality to wired and wireless networks. It works with Cisco
access-layer LAN products like access layer switches. Refer to
BBSM documentation for more information.
BBSM performs RADIUS authentication and authorization of end users (of
a specific VLAN). Each time the end user attempts to connect to the Internet,
BBSM prompts for a username and password. The values entered are used in the
Access-Request packet to the RADIUS authentication server. Upon successful
authentication, the RADIUS server sends a vendor-specific attribute that
contains a bandwidth kbps value in the Access-Accept packet.
When the RADIUS server sends this vendor-specific attribute that
contains a bandwidth kbps value, BBSM throttles the bandwidth of the end user
session to the kbps value specified. In order to use this feature,
administrators need to configure their RADIUS server to send the
vendor-specific attribute to transmit a Vendor ID of 5263, a Vendor type of 1,
and the integer value of the bandwidth kbps desired for the user
BBSM - Using RADIUS Authentication, Authorization, and Accounting for
more information on how BBSM works with a RADIUS server for user authentication
and bandwidth management.
BBSM Bandwidth Management on how to control a users bandwidth in
Also, refer to
Cisco 2900XL/3500XL Switches with VLANs to Use Cisco BBSM 5.0 for
detailed information on how to configure the upstream switches of a client with
VLANs in order to work with BBSM.