H3C Technologies H3C S3100 Series Switches - Manual (Page 211)

1-8
z When you add a MAC address entry, the current port must belong to the VLAN specified by the
vlan argument in the command. Otherwise, the entry will not be added.
z If the VLAN specified by the vlan argument is a dynamic VLAN, after a static MAC address is
added, it will become a static VLAN.
Setting the MAC Address Aging Timer
Setting an appropriate MAC address aging timer is important for the switch to run efficiently.
z If the aging timer is set 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 timer is set too short, the switch may remove valid MAC address entries. This
decreases the forwarding performance of the switch.
Follow these steps to set aging time of MAC address entries:
To do… Use the command… Remarks
Enter system view system-view —
Set the MAC address aging timer
mac-address timer { aging age |
no-aging } Required
The default is 300 seconds.
The capacity of the MAC address table on a switch is limited. After the limit is reached, the switch will
forward the frames received with unknown source MAC addresses without learning MAC addresses. In
case the MAC address table gets full, you can tune the aging timer to a smaller value to speed up MAC
address entry aging so that new MAC addresses can be learned.
Normally, you are recommended to use the default aging timer, namely, 300 seconds. The no-aging
keyword specifies that MAC address entries never age out.
MAC address aging configuration applies to all ports, but only takes effect on dynamic MAC addresses,
which are either learnt or configured.
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.