Cisco WS-C2980G-A Software Guide - Page 309

16 C H A P T E R Configuring Port Security This chapter describes how to configure port security on the Catalyst enterprise LAN switches. Note For complete syntax and usage information for the commands used in this chapter, refer to the Catalyst 4500 Series, Catalyst 2948G, and Catalyst 2980G Switches Command Reference. This chapter consists of these sections: • Understanding How Port Security Works, page 16-1 • Port Security Configuration Guidelines, page 16-3 • Configuring Port Security on the Switch, page 16-3 • Monitoring Port Security, page 16-10 Understanding How Port Security Works You can use port security to block input to an Ethernet, Fast Ethernet, or Gigabit Ethernet port when the MAC address of the station attempting to access the port is different from any of the MAC addresses that are specified for that port. Alternatively, you can use port security to filter traffic that is destined to or received from a specific host that is based on the host MAC address. Allowing Traffic Based on the Host MAC Address The total number of MAC addresses that can be specified per port is limited to the global resource of 1024 plus 1 default MAC address. That is, the total number of MAC addresses on any port cannot exceed 1025. The maximum number of MAC addresses that you can allocate for each port depends on your network configuration. The following combinations are valid allocations: • 1025 (1 + 1024) addresses on one port and 1 address each on the rest of the ports • 513 (1 + 512) each on two ports in a system and 1 address each on the rest of the ports • 901 (1 + 900) on one port, 101 (1 + 100) on another port, 25 (1 + 24) on a third port, and 1 address on each of the rest of the ports 78-15486-01 Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide-Release 8.1 16-1