Types of MAC Addresses

There are two types of MAC addresses: static and dynamic. Depending on their type, MAC addresses are either stored in the Static Address table or in the Dynamic Address table, along with VLAN and port information.

Static addresses are configured by the user, and therefore, they do not expire. A new source MAC address that appears in a frame arriving at the switch is added to the Dynamic Address table. This MAC address is retained for a configurable period of time. If another frame with the same source MAC address does not arrive at the switch before that time period expires, the MAC entry is aged (deleted) from the table.

When a frame arrives at the switch, the switch searches for a corresponding or matching destination MAC address entry in the static or dynamic table. If a match is found, the frame is marked for egress on the port specified in the table. If frames are sent to a MAC address that is not found in the tables, they are transmitted or broadcasted to all ports on the relevant VLAN. Such frames are referred to as unknown Unicast frames.