<P> BT (British Telecom, PLC) employs Identity Federation for authentication in services delivered to a wide variety of industries and governments . </P> <P> Not all devices support 802.1 X authentication . Examples include network printers, Ethernet - based electronics like environmental sensors, cameras, and wireless phones . For those devices to be used in a protected network environment, alternative mechanisms must be provided to authenticate them . </P> <P> One option would be to disable 802.1 X on that port, but that leaves that port unprotected and open for abuse . Another, slightly more reliable option is to use the MAB option . When MAB is configured on a port, that port will first try to check if the connected device is 802.1 X compliant, and if no reaction is received from the connected device, it will try to authenticate with the AAA server using the connected device's MAC address as username and password . The network administrator then must make provisions on the RADIUS server to authenticate those MAC - addresses, either by adding them as regular users, or implementing additional logic to resolve them in a network inventory database . </P> <P> Many managed Ethernet switches offer options for this . </P>

What device is used as the authentication server in an 802.1x implementation