By default, an unlimited number of MAC addresses can be learned on a single switch port, whether it is configured as an access port or a trunk port. Switches dynamically build MAC address tables in RAM, which allow the switch to forward incoming frames to the correct target port. Once the approved MAC addresses have all been learned, the network administrator simply saves the running-configuration file to NVRAM with the copy running-config startup-config command. Dynamically locked addresses can be converted to statically locked addresses.Issuing the switchport port-security mac-address sticky command will allow a switch to save a dynamically learned MAC address in the running-configuration of the switch, which prevents the administrator from having to document or configure specific MAC addresses. You can manually specify a list of static MAC addresses for a port. Static MAC addresses are not eligible for aging. Dynamically locked MAC addresses are eligible to be learned by another port. Dynamically locked MAC addresses are aged out if another packet with that address is not seen within the age-out time. Note: If you want to set a specific MAC address for a port, set the dynamic entries to 0, then allow only packets with a MAC address matching the MAC address in the static list.ĭynamically locked addresses can be converted to statically locked addresses. Only frames with an allowable source MAC addresses are forwarded. After the limit is reached, additional MAC addresses are not learned. The maximum number of MAC addresses is platform dependent and is given in the software Release Notes. You can specify the maximum number of MAC addresses that can be learned on a port. Port security implements two traffic filtering methods, dynamic locking and static locking. You can enable port security on a per port basis.Packets that have a matching MAC address (secure packets) are forwarded all other packets (unsecure packets) are restricted.

You can limit the number of MAC addresses on a given port.The port security feature offers the following benefits:

When a link goes down, all dynamically locked addresses are freed.

Port Security helps secure the network by preventing unknown devices from forwarding packets.

Dynamically learned mac addresses