How do you set the maximum number of MAC (Media Access Control) addresses on a secure port, and what is the range?

Use switchport port-security maximum <value> to set the limit. The default is 1; the maximum depends on the switch model (e.g., 8192 on a Catalyst 6500).

Configuration:

Switch(config)# interface FastEthernet 0/1
Switch(config-if)# switchport mode access
Switch(config-if)# switchport port-security
Switch(config-if)# switchport port-security maximum 2

When to increase the maximum:

• A port connected to an IP (Internet Protocol) phone with a PC behind it → needs at least 2 (phone MAC + PC MAC)
• A port connected to a small hub or unmanaged switch → set to the expected number of devices
• A port connected to a virtualization host → multiple VMs may use different MACs

When to keep the default of 1:

• Standard user access ports (one PC per port)
• Printer ports
• Single-device ports

Important: Setting the maximum to a very high value (e.g., 100) defeats the purpose of port security against MAC flooding attacks. Keep it as low as practical.

Go deeper:

• Switchport Port-Security (NetworkAcademy.IO) — the maximum command in the context of the full feature.