A software MAC address table is continued on the Cisco ME 2600X. This MAC address table contains the MAC addresses accomplished on all the interfaces of Cisco ME 2600X.
- To exchange frames between LAN ports efficiently, the switch continues an address table called the MAC table.
- When the switch receives a frame, it associates the media access control (MAC) address of the dispatching network device with the LAN port on which it was received.
- The switch dynamically constructs the address table using the MAC source address of the received frames.
- When the switch receives a frame for a destination MAC address that is not in its address table, it floods the frame of all the LAN ports of the same VLAN except for the port that the frame received.
- When the destination station responds, the switch adds its relevant MAC source address and port ID to the address table.
- The switch then forwards the subsequent frames to a single LAN port without flooding all the LAN ports.
- You can also enter a MAC address, which is called static MAC address, in the table.
- These static MAC inputs are retained during a switch reset.
MAC Address Aging
The dynamically learned MAC addresses are deleted after the MAC address age value has expired. This frees unused addresses from the MAC address table for other active subscribers. In Cisco ME 2600X, the default value for aging the MAC address is 300 seconds and can not be changed. The expected MAC address expiration timer is between 300 and 600 seconds, depending on the number of MAC addresses learned.
- You can configure the amount of time an entry remains in the MAC table.
- You can also configure MAC aging time in interface configuration mode or in VLAN configuration mode.
- The MAC aging time specifies the time before entry ages and is discarded from the MAC address table.
- The range is from 0 to 1000000; The default value is 300 seconds.
- Entering the value 0 disables MAC aging.
- If a VLAN is not specified, the age specification applies to all VLANs.
Dynamic MAC Address Learning
Dynamic learning of MAC addresses occurs when the bridge data path encounters an input frame whose source address is not present in the MAC address table for the incoming service instance. The learned MAC addresses are distributed to the other cards with Ethernet Flow Points (EFP) in the same bridge domain.
A MAC move occurs when the same MAC address is again learned on an another port. When a MAC move is detected, a fleeting event is generated to advise the user about the MAC move.