23-9
Catalyst 2975 Switch Software Configuration Guide
OL-19720-02
Chapter 23 Configuring Port-Based Traffic Control
Configuring Port Security
To return the interface to the default condition where no traffic is blocked and normal forwarding occurs
on the port, use the
no switchport block
{
multicast
|
unicast
} interface configuration commands.
This example shows how to block unicast and Layer 2 multicast flooding on a port:
Switch#
configure terminal
Switch(config)#
interface gigabitethernet1/0/1
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 addresses. If
you limit the number of secure MAC addresses to one and assign a single secure MAC address, the
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 flagged.
These sections contain this conceptual and configuration information:
•
Understanding Port Security, page 23-9
•
Default Port Security Configuration, page 23-11
•
Port Security Configuration Guidelines, page 23-12
•
Enabling and Configuring Port Security, page 23-13
•
Enabling and Configuring Port Security Aging, page 23-17
•
Port Security and Switch Stacks, page 23-18
Understanding Port Security
These sections contain this conceptual information:
•
Secure MAC Addresses, page 23-9
•
Security Violations, page 23-10
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.