Section: IP Connectivity

The 802.1x standard defines a client-server-based access control and authentication protocol that prevents unauthorized clients from connecting to a LAN through publicly accessible ports unless they are properly authenticated. The authentication server authenticates each client connected to a switch port before making available any services offered by the switch or the LAN.
Unused or "empty" ports within any network device pose a security risk, as someone might plug a cable into them and connect an unauthorised device to the network. This can lead to a number of issues, including:
Network not functioning as it should

Network information vulnerable to outsiders

Therefore, you should shut down every port that is not used on routers, switches, and other network devices. Depending upon the device, the shutdown state might be the default, but you should always verify this.