Cisco WS-C2960-24PC-L Software Guide - Page 311
Blocking Unicast Flood Packets on Secure Ports, Port Security Configuration Guidelines
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Chapter 16 Configuring Port Security Port Security Configuration Guidelines Blocking Unicast Flood Packets on Secure Ports You can block unicast flood packets on a secure Ethernet port by disabling the unicast flood feature. If you disable unicast flood on a port, the port will drop unicast flood packets when the port reaches the allowed maximum number of MAC addresses. The port automatically restarts unicast flood packet learning when the number of MAC addresses drops below the maximum number that is allowed. The learned MAC address count decreases when a configured MAC address is removed or a time to live counter (TTL) is reached. Port Security Configuration Guidelines This section lists the guidelines for configuring port security: • Do not configure port security on a SPAN destination port. • Do not configure SPAN destination on a secure port. • Do not configure dynamic, static, or permanent CAM entries on a secure port. Configuring Port Security on the Switch The following sections describe how to configure port security. Enabling Port Security Port security is either autoconfigured or enabled manually by specifying a MAC address. If a MAC address is not specified, the source address from the incoming traffic is autoconfigured and secured, up to the maximum number of MAC addresses allowed. These autoconfigured MAC Addresses remain secured for a time, depending upon the aging timer set. The autoconfigured MAC Addresses are cleared from the port in case of a link-down event. When you enable port security on a port, any static or dynamic CAM entries that are associated with the port are cleared; any currently configured permanent CAM entries are treated as secure. To enable port security, perform this task in privileged mode: Step 1 Step 2 Step 3 Task Enable port security on the desired ports. If desired, specify the secure MAC address. You can add MAC addresses to the list of secure addresses. Verify the configuration. Command set port security mod_num/port_num enable [mac_addr] set port security mod_num/port_num mac_addr show port [mod_num[/port_num]] This example shows how to enable port security using the learned MAC address on a port: Console> (enable) set port security 2/1 enable Port 2/1 port security enabled with the learned mac address. Trunking disabled for Port 2/1 due to Security Mode 78-15486-01 Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide-Release 8.1 16-3
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