The IEEE 802.1X authentication with wake on LAN (WoL) feature allows dormant PCs to be powered when the switch receives a specific Ethernet frame, known as the “magic packet.” You can use this feature in environments where administrators need to connect to systems that have been powered off.
When a host that uses WoL is attached through an 802.1X port and the host powers off, the 802.1X port becomes unauthorized. The port can only receive and send EAPOL packets, and WoL magic packets cannot reach the host. When the PC is powered off, it is not authorized, and the switch port is not opened.
When the switch uses 802.1X authentication with WoL, the switch forwards traffic to unauthorized 802.1x ports, including magic packets. While the port is unauthorized, the switch continues to block ingress traffic other than EAPOL packets. The host can receive packets but cannot send packets to other devices in the network.
If PortFast is not enabled on the port, the port is forced to the bidirectional state.
When you configure a port as unidirectional by using the
authentication control-direction command in interface configuration command, the port changes to the spanning-tree forwarding state. The port can send packets to the host but cannot receive packets from the host.
When you configure a port as bidirectional by using the authentication control-direction both interface configuration command, the port is access-controlled in both directions. The port does not receive packets from or send packets to the host.