As we saw in Chapter 6, 802.1x is a port-based authentication mechanism. Note that when we talk about ports in an 802.1x context, we are talking about physical ports (not higher-layer ports such as Port 80 on a Web server). Since 802.1x applies to both wired and wireless networks, these physical ports can be actual, physical ports (such as in a Layer 2 switch), or they can be virtual ports, as in the case of an AP.
An 802.1x architecture is made up of three components:
The supplicant, which is the client machine
The authenticator, which is the middleman (typically the AP)
The authentication server, which is typically a RADIUS server