Access device as the initiator
The access device initiates authentication, if a client, the 802.1X client available with Windows XP for example, cannot send EAPOL-Start packets.
The access device supports the following modes:
Multicast trigger mode—The access device multicasts Identity EAP-Request packets periodically (every 30 seconds by default) to initiate 802.1X authentication.
Unicast trigger mode—Upon receiving a frame with the source MAC address not in the MAC address table, the access device sends an Identity EAP-Request packet out of the receiving port to the unknown MAC address. It retransmits the packet if no response has been received within a certain time interval.