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Configuring Fast Roaming for Wireless Clients

Instant supports the following features that enable fast roaming of clients:

Opportunistic Key Caching
Fast BSS Transition (802.11r Roaming)
Radio Resource Management (802.11k)
BSS Transition Management (802.11v)

Opportunistic Key Caching

Instant now supports opportunistic key caching (OKC) based roaming. In the OKC based roaming, the AP stores one pairwise master key (PMK) per client, which is derived from last 802.1x authentication completed by the client in the network. The cached PMK is used when a client roams to a new AP. This allows faster roaming of clients between the IAPs in a cluster, without requiring a complete 802.1X authentication.

 

OKC roaming (when configured in the 802.1x Authentication profile) is supported on WPA2 clients. If the wireless client (the 802.1X supplicant) does not support this feature, a complete 802.1X authentication is required whenever a client roams to a new AP.

Configuring an IAP for OKC Roaming

You can enable OKC roaming for WLAN SSID by using Instant UI or CLI.

In the Instant UI

1. Navigate to the WLAN wizard (click Network>New or Network> Select the WLAN SSID>edit).
2. Click the Security tab.
3. Slide to Enterprise security level. On selecting a security level, the authentication options applicable to Enterprise network are displayed.

4. Select the WPA-2 Enterprise or Both (WPA-2 & WPA) option from the Key management drop-down list. When any of these encryption types is selected, Opportunistic Key Caching (OKC) is enabled by default.
5. Click Next and then click Finish.

In the CLI

To disable OKC roaming on a WLAN SSID:

(Instant AP)(config)# wlan ssid-profile <name>

(Instant AP)(SSID Profile <name>)# opmode {wpa2-aes|wpa-tkip,wpa-aes,wpa2-tkip,wpa2-aes}

(Instant AP)(SSID Profile <name>)# okc-disable

(Instant AP)(config)# end

(Instant AP)# commit apply

To enable OKC roaming on a WLAN SSID:

(Instant AP)(config)# wlan ssid-profile <name>

(Instant AP)(SSID Profile <name>)# opmode {wpa2-aes| wpa-tkip,wpa-aes,wpa2-tkip,wpa2-aes}

(Instant AP)(SSID Profile <name>)# no okc-disable

(Instant AP)(config)# end

(Instant AP)# commit apply

Fast BSS Transition (802.11r Roaming)

802.11r is a roaming standard defined by IEEE. When enabled, 802.11r reduces roaming delay by pre-authenticating clients with multiple target APs before a client roams to an AP. With 802.11r implementation, clients pre-authenticate with multiple APs in a cluster.

As part of the 802.11r implementation, Instant supports the Fast BSS Transition protocol. The Fast BSS Transition mechanism reduces client roaming delay when a client transitions from one BSS to another within the same cluster. This minimizes the time required to resume data connectivity when a BSS transition happens.

 

Fast BSS Transition is operational only if the wireless client supports 802.11r standard. If the client does not support 802.11r standard, it falls back to the normal WPA2 authentication method.

Configuring an IAP for 802.11r support

You can configure 802.11r support for a WLAN SSID by using the Instant UI or CLI.

In the Instant UI

1. Navigate to the WLAN wizard (click Network>New or Network> Select the WLAN SSID>edit).
2. Click the Security tab.
3. Under Fast Roaming, select the 802.11r checkbox.
4. Click Next and then click Finish.

In the CLI

To enable 802.11r roaming on a WLAN SSID:

(Instant AP)(config)# wlan ssid-profile <name>

(Instant AP)(SSID Profile <name>)# dot11r

(Instant AP)(config)# end

(Instant AP)# commit apply

Example

(Instant AP)(config)# wlan ssid-profile dot11r-profile

(Instant AP)(SSID Profile "dot11r-profile")# dot11r

(Instant AP)(config)# end

(Instant AP)# commit apply

Radio Resource Management (802.11k)

The 802.11k protocol provides mechanisms for APs and clients to dynamically measure the available radio resources and enables stations to query and manage their radio resources. In an 802.11k enabled network, APs and clients can share radio and link measurement information, neighbor reports, and beacon reports with each other. This allows the WLAN network infrastructural elements and clients to assess resources and make optimal mobility decisions to ensure Quality of Service (QoS) and seamless continuity.

Instant supports the following radio resource management information elements with 802.11k support enabled:

Power Constraint IE—The power constraint element contains the information necessary to allow a client to determine the local maximum transmit power in the current channel.
AP Channel Report IE—The AP channel report element contains a list of channels in a regulatory class where a client is likely to find an AP, including the AP transmitting the AP channel report.
RRM Enabled Capabilities IE—The RRM Enabled Capabilities element signals support for radio measurements in a device. The clients use this IE to specify their radio measurement capabilities.
BSS Load Element: The BSS Load element contains information on the density of clients and traffic levels in the QBSS.
Transmit Power Control (TPC) Report IE: The TPC IE contains transmit power and link margin information.
Quiet IE: The Quiet IE defines an interval during which no transmission occurs in the current channel. This interval may be used to assist in making channel measurements without interference from other stations in the BSS.
Extended Capabilities IE - The extended capabilities IE carries information about the capabilities of an IEEE 802.11 station.

Beacon Report Requests and Probe Responses

The beacon request frame is sent by an AP to request a client to report the list of beacons heard by the client on all channels.

The beacon request is sent using the radio measurement request action frame.
It is sent only to those clients that have the capability to generate beacon reports. The clients indicate their capabilities through the RRM enabled capabilities IE sent in the association request frames.
By default, the beacon request frames are sent at a periodicity of 60 seconds.

Configuring a WLAN SSID for 802.11k Support

You can enable 802.11k support on a WLAN SSID by using the Instant UI or CLI.

In the Instant UI

1. Navigate to the WLAN wizard (click Network>New or Network> Select the WLAN SSID>edit).
2. Click the Security tab.
3. Under Fast Roaming, Select the 802.11k checkbox.
4. Click Next and then click Finish.

 

To allow the AP and clients to exchange neighbor reports, ensure that the Client match is enabled through RF > ARM > Client match > Enabled in the UI or by executing the client-match command in the arm configuration sub-mode.

In the CLI

To enable 802.11k profile:

(Instant AP)(config)# wlan ssid-profile <name>

(Instant AP)(SSID Profile <name>)# dot11k

(Instant AP)(config)# end

(Instant AP)# commit apply

To view the beacon report details:

show ap dot11k-beacon-report <mac>

To view the neighbor details:

show ap dot11k-nbrs

Example

(Instant AP)(config)# wlan ssid-profile dot11k-profile

(Instant AP)(SSID Profile "dot11k-profile")# dot11k

(Instant AP)(config)# end

(Instant AP)# commit apply

BSS Transition Management (802.11v)

The 802.11v standard provides Wireless Network Management enhancements to the IEEE 802.11 MAC and PHY. It extends radio measurements to define mechanisms for wireless network management of stations including BSS transition management.

IAPs support the generation of the BSS transition management request frames to the 802.11k clients when a suitable AP is identified for a client through client match.

Configuring a WLAN SSID for 802.11v Support

You can enable 802.11v support on a WLAN SSID by using the Instant UI or CLI.

In the Instant UI

1. Navigate to the WLAN wizard (click Network>New or Network> Select the WLAN SSID>edit).
2. Click the Security tab.
3. Under Fast Roaming, Select the 802.11v checkbox.
4. Click Next and then click Finish.

In the CLI

To enable 802.11v profile:

(Instant AP)(config)# wlan ssid-profile <name>

(Instant AP)(SSID Profile <name>)# dot11v

(Instant AP)(config)# end

(Instant AP)# commit apply

Example

(Instant AP)(config)# wlan ssid-profile dot11v-profile

(Instant AP)(SSID Profile "dot11v-profile")# dot11v

(Instant AP)(config)# end

(Instant AP)# commit apply