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Aironet Extensions and Centrino

Can anyone tell me if Aironet extensions should or should not be enabled on 1200 AP's. All of our clients are IBM/Lenovo using Intel Centrino.

Thanks,

Bob

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Hall of Fame Super Red

Re: Aironet Extensions and Centrino

Hi Bob,

From everything I know about "Aironet Extensions" they should be disabled in your environment. They are primarily used with Cisco Aironet Wireless adaptors and aren't going to help you here. Have a look;

Disabling and Enabling Aironet Extensions

By default, the access point uses Cisco Aironet 802.11 extensions to detect the capabilities of Cisco Aironet client devices and to support features that require specific interaction between the access point and associated client devices. Aironet extensions must be enabled to support these features:

Load balancing The access point uses Aironet extensions to direct client devices to an access point that provides the best connection to the network based on factors such as number of users, bit error rates, and signal strength.

Message Integrity Check (MIC) MIC is an additional WEP security feature that prevents attacks on encrypted packets called bit-flip attacks. The MIC, implemented on both the access point and all associated client devices, adds a few bytes to each packet to make the packets tamper-proof.

Cisco Key Integrity Protocol (CKIP) Cisco's WEP key permutation technique based on an early algorithm presented by the IEEE 802.11i security task group. The standards-based algorithm, TKIP, does not require Aironet extensions to be enabled.

Repeater mode Aironet extensions must be enabled on repeater access points and on the root access points to which they associate.

World mode (legacy only) Client devices with legacy world mode enabled receive carrier set information from the access point and adjust their settings automatically. Aironet extensions are not required for 802.11d world mode operation.

Limiting the power level on associated client devices When a client device associates to the access point, the access point sends the maximum allowed power level setting to the client.

Disabling Aironet extensions disables the features listed above, ***but it sometimes improves the ability of non-Cisco client devices to associate to the access point.

Aironet extensions are enabled by default.

From this doc;

http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo1100/accsspts/i12215ja/i12215sc/s15rf.htm#wp1038065

Hope this helps!

Rob

4 REPLIES
Hall of Fame Super Red

Re: Aironet Extensions and Centrino

Hi Bob,

From everything I know about "Aironet Extensions" they should be disabled in your environment. They are primarily used with Cisco Aironet Wireless adaptors and aren't going to help you here. Have a look;

Disabling and Enabling Aironet Extensions

By default, the access point uses Cisco Aironet 802.11 extensions to detect the capabilities of Cisco Aironet client devices and to support features that require specific interaction between the access point and associated client devices. Aironet extensions must be enabled to support these features:

Load balancing The access point uses Aironet extensions to direct client devices to an access point that provides the best connection to the network based on factors such as number of users, bit error rates, and signal strength.

Message Integrity Check (MIC) MIC is an additional WEP security feature that prevents attacks on encrypted packets called bit-flip attacks. The MIC, implemented on both the access point and all associated client devices, adds a few bytes to each packet to make the packets tamper-proof.

Cisco Key Integrity Protocol (CKIP) Cisco's WEP key permutation technique based on an early algorithm presented by the IEEE 802.11i security task group. The standards-based algorithm, TKIP, does not require Aironet extensions to be enabled.

Repeater mode Aironet extensions must be enabled on repeater access points and on the root access points to which they associate.

World mode (legacy only) Client devices with legacy world mode enabled receive carrier set information from the access point and adjust their settings automatically. Aironet extensions are not required for 802.11d world mode operation.

Limiting the power level on associated client devices When a client device associates to the access point, the access point sends the maximum allowed power level setting to the client.

Disabling Aironet extensions disables the features listed above, ***but it sometimes improves the ability of non-Cisco client devices to associate to the access point.

Aironet extensions are enabled by default.

From this doc;

http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo1100/accsspts/i12215ja/i12215sc/s15rf.htm#wp1038065

Hope this helps!

Rob

Community Member

Re: Aironet Extensions and Centrino

Thanks for the information. The information provided makes sense..Bob

Bronze

Re: Aironet Extensions and Centrino

Is the "Aironet IE" in LWAPP APs the same as "Aironet Extensions" in autonomous APs? I think "Aironet IE" works with all CCX cards, not just Cisco Aironet cards. Should we disable "Aironet IE" on WLCs when working with Intel Centrino cards?

Thanks

Zhenning

Hall of Fame Super Red

Re: Aironet Extensions and Centrino

Hi Zhenning (How are things in Guelph),

I am sure that you are correct here in that Aironet IE (LWAPP) differs from Aironet Extensions (IOS) quite a bit. The IE (Information Element) provides support for various features for user machines running CCX (Cisco Compatible Extensions) I don't think that you should disable Aironet IE on the WLC. Have a look :)

Configuring Cisco Client Extensions

Cisco Client Extensions (CCX) software is licensed to manufacturers and vendors of third-party client devices. The CCX code resident on these clients enables them to communicate wirelessly with Cisco access points and to support Cisco features that other client devices do not, including those related to increased security, enhanced performance, fast roaming, and superior power management.

The 4.0 release of controller software supports CCX versions 1 through 4, which enables controllers and their access points to communicate wirelessly with third-party client devices that support CCX. CCX support is enabled automatically for every WLAN on the controller and cannot be disabled. However, you can configure a specific CCX feature per WLAN. This feature is Aironet information elements (IEs).

If Aironet IE support is enabled, the access point sends an Aironet IE 0x85 (which contains the access point name, load, number of associated clients, and so on) in the beacon and probe responses of this WLAN, and the controller sends Aironet IEs 0x85 and 0x95 (which contains the management IP address of the controller and the IP address of the access point) in the reassociation response if it receives Aironet IE 0x85 in the reassociation request.

A client device sends its CCX version in association request packets to the access point. The controller then stores the client's CCX version in its database and uses it to limit the features for this client. For example, if a client supports CCX version 2, the controller does not allow the client to use CCX version 4 features.

From this doc;

http://www.cisco.com/en/US/products/ps6366/products_configuration_guide_chapter09186a008076cbfd.html#wp1093368

Hope this helps!

Rob

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