The animated TECHTip tutorial available here.

With fast secure roaming, authenticated client devices can roam securely at L2-Layer 2 Datalink from one access point to another without any perceptible delay during reassociation. FSR is designed for latency-sensitive applications such as WVoIP [Wireless Voice Over Internet Protocol], transaction processing, or other low-latency (no delay - real-time applications). WDS provides fast, secure handoff services to access points, without dropping connections, for fewer than 150ms roaming within a LAN [Local Area Network] subnet.

Cisco FSR [Fast Secure Roaming] reduces to as little as 150 milliseconds reconnection of Wi-Fi devices from one AP [Access Point] to another. Designed for use with WVoIP, FSR provides fast and secure handoff (also known as handover) services without dropping connections. Here’s how FSR works:

1. Access Point must now 802.1x authenticate with the Cisco WDS [Wireless Domain Service] AP (1) to establish a secure session.

2. Initial client 802.1x authentication goes to the central AAA [Authentication Authorization Accounting] server (~500 ms-milliseconds).
3. Client roams to new AP (2). WDS will send the client’s base key to AP (2).
4. Overall re-authentication has been reduced to 100-150 ms. Because the WDS has processed authentication, WAN link is not used.

Not to be confused with MobileIP at Layer 3 Network, FSR is a Layer 2 Datalink function. In addition, FSR support many of the key security systems such as CCKM [Cisco Client Key Management], LEAP, MIC [Message Integrity Check] (also known as MIChael), TKIP [Temporal Key Integrity Protocol]. FSR is supported by Cisco Aironet 1200 and 1100 Series AP.

We conclude with a site planning TECHTip. The 802.1b standard provides for three non-interfering channels: 1, 6, and 11. APs within range of each other should always be set to non-interfering channels to maximize the capacity and performance of the Wi-Fi network. This approach makes designing your Wi-Fi network for WVoIP and other wireless devices easy.

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