1-6 
Setting the Aging Time of MAC Address Entries 
Setting aging time properly helps effective utilization of MAC address aging. The aging time that is too 
long or too short affects the performance of the switch. 
z  If the aging time is too long, excessive invalid MAC address entries maintained by the switch may 
fill up the MAC address table. This prevents the MAC address table from being updated with 
network changes in time. 
z  If the aging time is too short, the switch may remove valid MAC address entries. This decreases the 
forwarding performance of the switch. 
Table 1-5 Set aging time of MAC address entries 
Operation  Command  Description 
Enter system view 
system-view 
— 
Set the aging time of MAC 
address entries 
mac-address timer { aging 
age | no-aging } 
Required 
The default aging time is 300 
seconds. 
 
Normally, you are recommended to use the default aging time, namely, 300 seconds. The no-aging 
keyword specifies that MAC address entries do not age out. 
 
 
MAC address aging configuration applies to all ports, but only takes effect on dynamic MAC addresses 
that are learnt or configured to age. 
 
Setting the Maximum Number of MAC Addresses a Port Can Learn 
The MAC address learning mechanism enables an Ethernet switch to acquire the MAC addresses of 
the network devices on the segment connected to the ports of the switch. By searching the MAC 
address table, the switch directly forwards the packets destined for these MAC addresses through the 
hardware, improving the forwarding efficiency. A MAC address table too big in size may prolong the time 
for searching MAC address entries, thus decreasing the forwarding performance of the switch. 
By setting the maximum number of MAC addresses that can be learnt from individual ports, the 
administrator can control the number of the MAC address entries the MAC address table can 
dynamically maintain. When the number of the MAC address entries learnt from a port reaches the set 
value, the port stops learning MAC addresses. 
Table 1-6 Set the maximum number of MAC addresses a port can learn 
Operation  Command  Description 
Enter system view 
system-view 
— 
Enter Ethernet port view 
interface interface-type 
interface-number 
—