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Quick “extended service set” setup routines for WiFi access points

Why a quick setup routine for WiFi access points (or client devices capable of operating as access points)?

It makes it simple for one to extend or improve wireless coverage by adding access points to an existing “extended service set” with a wired backbone. This includes mitigating microwave-oven interference to computer equipment being used in the kitchen by using an access point tuned to Channel 1 installed there. Increasingly this functionality will become more relevant with WiFi-based VoIP cordless phones and come in to its own with location-based WiFi security and home-automation applications. It will also allow a device with built-in Ethernet or HomePlug network connectivity as well as a WiFi client functionality (which typically covers most WiFi-enabled devices) to become a low-power WiFi access point thus making it easy to expand the wireless network by providing infill coverage.

This is achieved by enrolling the device as a client device of the wireless network, then if the device is connected to the same Internet gateway that is visited by the wireless network via the wired network, it sets itself up as an access point with the same SSID and security data as the master access point. It then avoids users having to re-enter network data and make mistakes in setting up multiple-access-point wireless networks.

Methods

Semi-automatic operation – without WPS on master AP

  1. User: Connect to new AP via Ethernet or HomePlug
  2. User: At Web UI for new access point:
    1. Select AP – quick setup
  3. New Access Point: AP becomes wireless client bridge, direct link to host
  4. New Access Point: AP presents list of SSIDs that it can receive and their security status (open or secure)
  5. User: Clicks on SSID matching their home network’s SSID or enters home network’s SSID (for hidden SSID networks), then enters WEP/WPA-PSK key as applicable when the new AP locks on to the desired AP
  6. New Access Point: Perform DHCP test to see if it can find the gateway
    1. If successful, offer to set up as AP, gain MAC of gateway & BSSID of master (& other) APs on SSID,set WEP/WPA-PSK parameter
  7. New Access Point: If user OKs with setting up as AP for network, then switch to AP mode, self-tune to vacant frequency, remain dormant
  8. New Access Point: Once gateway is discovered through Ethernet / HomePlug interface (backbone detect), activate AP mode.

Automatic operation – with WPS on master AP

  1. User: Select Access Point mode, then invoke WPS on new and master AP (PBC “push-push” method)
  2. New Access Point: new AP gains WiFi details through WPS as if it is a client
  3. New Access Point: become wireless client bridge on these details until connected to wired backbone
  4. New Access Point: detect wired backbone (via Ethernet, HomePlug), self-tune, become AP with WPS “peer” status

Limitations

Some details may not be able to be conveyed to the new access point, especially if the access point is of lesser capability than the master access point. This may be of concern when extending the coverage of a wireless hotspot and want to enforce client-computer isolation at the access point. The client-computer isolation functionality should be achieved at the link-layer level by the hotspot gateway router thus allowing for media-independent client isolation. It can then cater for hotspots that use wired media (Ethernet, HomePlug, MoCA TV-aerial cabling) to extend WiFi coverage or connect computers supplied by themselves or their guests to their Internet service.

Similarly there may be issues with setting up a multi-LAN wireless network where there is a VLAN set up on the wired network and multiple SSIDs that are radiated by the same access point. This kind of setup describes a “private” LAN segment and a “public” or “guest” LAN segment

Conclusion

Once the WiFi equipment vendors look at using “quick-setup” methods for WiFi access points, this can allow home and small-business users, especially those with limited computer skills, to set up their wireless networks to suit their needs more easily.

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18 August 2009 Posted by | Wireless Networking | , | 3 Comments