21-8
Cisco ME 3400 EthernetAccess Switch SoftwareConfiguration Guide
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Chapter21 Configuring Port-Based Traffic Control
Configuring Port Security
This example shows how to block unicast and multicast flooding on a port:
Switch# configure terminal
Switch(config)# interface fastethernet0/1
Switch(config-if)# no shutdown
Switch(config-if)# switchport block multicast
Switch(config-if)# switchport block unicast
Switch(config-if)# end
Configuring Port Security
You can use the port security feature to restrict input to an interface by limiting and identifying MAC
addresses of the stations allowed to access the port. When you assign secure MAC addresses to a secure
port, the port does not forward packets with source addresses outside the group of defined add resses. If
you limit the number of secure MAC addresses to one and assign a singl e se cu re M AC address, th e
workstation attached to that port is assured the full bandwidth of the port.
If a port is configured as a secure port and the maximum number of secure MAC addresses is reached,
when the MAC address of a station attempting to access the port is different from any of the identified
secure MAC addresses, a security violation occurs. Also, if a station with a secure MAC address
configured or learned on one secure port attempts to access another secure port, a violation is flagg ed.
These sections contain this conceptual and configuration in forma tion:
•Understanding Port Security, page 21-8
•Default Port Security Configuration, page 21-10
•Port Security Configuration Guidelines, page 21-10
•Enabling and Configuring Port Security, page 21-11
•Enabling and Configuring Port Security Aging, page 21-15

Understanding Port Security

These sections contain this conceptual information:
•Secure MAC Addresses, page 21-8
•Security Violations, page 21-9

Secure MAC Addresses

You configure the maximum number of secure addresses allowed on a port by using the switchport
port-security maximum value interface configuration command.
Note If you try to set the maximum value to a number less than the number of secure addresses already
configured on an interface, the command is rejected.
The switch supports these types of secure MAC addresses:
•Static secure MAC addresses—These are manually configured by using th e switchport
port-security mac-address mac-address interface configuration command, stored in the address
table, and added to the switch running configuration.