Description and configuration steps of port blocking

Port Blocking
By default, flood packets with unknown destination MAC addresses can be transmitted from the port. If an unknown unicast or multicast communication is forwarded to the protected port, security issues may occur. Blocking ports can be used to prevent unknown unicast and multicast communication from being forwarded between ports.
Step 1: Enter the global configuration mode.

Switch # config Terminal

Step 2: Specifies the interface to be configured.

Switch (config) # interface-ID

Step 3: Prohibit unknown Multicast from transmitting from this port.

Switch (config-If) # switchport block Multicast

Step 4: Prohibit unknown unicast from transmitting from this port.

Switch (config-If) # switchport block unicast

Step 5: Returns the privileged configuration mode.

Switch (config-If) # End

Step 6: Displays and verifies the current configuration of this interface.

Switch # Show interfaces interface-ID switchport

Step 7: Save the configuration.

Switch # copy running-config startup-config