H3C Technologies H3C S3100 Series Switches - Manual (Page 171)

Operation Manual – MAC Address Table
H3C S3100-52P Ethernet Switch
Chapter 1 MAC Address Table
Management
1-5
Caution:
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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.
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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.
1.2.2 Setting the Aging Time of MAC Address Entries
Setting aging time properly helps implement effective MAC address aging. The aging
time that is too long or too short results in a large amount of broadcast packets
wandering across the network and decreases the performance of the switch.
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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.
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If the aging time is too short, the switch may remove valid MAC address entries.
This decreases the forwarding performance of the switch.
Table 1-4
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.
This command is used in system view and applies to all ports. Aging applies to only
dynamic MAC addresses that are learnt or configured to age.
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.
1.2.3 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.
The switch directly forwards the packets destined for these MAC addresses. A MAC
address table too big in size may decrease the forwarding performance of the switch.
By setting the maximum number of MAC addresses that can be learnt from individual
ports, you can control the number of the MAC address entries the MAC address table