Managing the MAC Address Table 84930Managing the MAC Address TableThis chapter describes the L2 MAC address table the switch uses to forwarddata between ports.The topics covered in this chapter include:• MAC Address Table Overview• Default MAC Address Table Values• Managing the MAC Address Table (Web)• Managing the MAC Address Table (CLI)MAC Address Table OverviewThe MAC address table keeps track of the MAC addresses that are associatedwith each port to allow the switch to forward unicast traffic through theappropriate port. This table is sometimes called the bridge table or theforwarding database.How Is the Address Table Populated?The MAC address table can contain two types of addresses:• Static: The address has been manually configured and does not age out.• Dynamic: The address has been automatically learned by the switch andcan age out when it is not in use.Static addresses are configured by the administrator and added to the table.Dynamic addresses are learned by examining information in the Ethernetframe.When a frame arrives on a port, the switch looks at the frame header to learnthe source MAC address of the frame, then adds the address, VLAN ID, andthe ingress port to the MAC address table. The address table is constantlyupdated as new addresses are learned, and unused addresses age out.A frame that has a destination MAC address that matches an entry in thetable is forwarded immediately to the associated port(s)/VLAN(s).
