Building a Wi-Fi network that delivers uninterrupted coverage to roaming devices can be a significant challenge—especially as coverage requirements increase.
Basic roaming occurs when a wireless client device moves outside the usable range of one wireless access point (AP) and connects to another AP—usually one with a stronger signal. The challenge comes during the actual “hand-off ” process, which, according to the IEEE 802.11 standard , is dictated by the client device. The hand-off is the process of the client device disconnecting from one AP and then re-associating with another. This process consists of three phases:
- Scanning: As the device moves away from the AP to which it is connected and the RSSI values begin to drop, the client device sends packets to identify AP alternatives. Upon discovery of accessible APs, the device then selects its next AP based on specific criteria.
- Authentication: During this phase, the client device sends an authentication request to the new AP and waits for a response from the AP to approve or reject the request.
- Re-association: Upon approval by the new AP, the client sends a re-association request and waits for a response. Once the re-association is complete, the new AP sends out a disassociation packet to the old AP so that the routing tables can be updated.
Basic Roaming can take as many as 10 seconds.
IGX Lightening Advanced-Roaming few as 100 ms.
Intelligraphics Advanced Roaming incorporates heuristic roaming methods with a pre-determined model that calculates roaming conditions, solving major portions of necessary analysis long before the actual roam decision.
- Pre-scan occurs before the actual roam phase
- Candidate AP selection as part of pre-roam algorithm
- AP ranking occurs within the pre-roam algorithm
- All roaming independent of infrastructure and AP configuration
- Optimized BG scan and BG scan parameters
- Full scan channel selection and control
- Prevents loss of connection to upper stack during the advanced roaming phase
- Uses multiple triggers as source for roaming, including RSSI, signal, rate error, and beacon miss
- Adjustable roaming parameters
- Cisco Compatible Extensions (CCX) v4
- Advanced power management
- Industrial temperature range
- Integrated configuration utility with network profiles
- PMK Caching
WPA and WPA2 Enterprise Security
Support for 802.1x EAP types:
- EAP Fast
- EAP TLS
- PEAP GTC
- PEAP MSCHAPv2
- PEAP TLS
- EAP TTLS
- PEAP TLS
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