H3C Technologies H3C S12500 Series Switches - Manual (Page 62)

49
Configuring the aging timer for dynamic MAC
address entries
The MAC address table on your switch uses an aging mechanism for dynamic entries, so dynamic MAC
address entries that are not updated within their aging time are deleted to make room for new entries,
and the MAC address table is promptly updated to accommodate the latest network changes.
Configuration restrictions and guidelines
Set the aging timer appropriately. Too long an aging interval might cause the MAC address table to
retain outdated entries, exhaust the MAC address table resources, and fail to update its entries to
accommodate the latest network changes. Too short an interval might result in removal of valid entries,
causing unnecessary broadcasts, which might affect switch performance.
The MAC address aging timer takes effect globally on dynamic MAC address entries (learned or
administratively configured) only.
In a stable network, when there has been no traffic activity for a long time, all dynamic entries in the MAC
address table maintained by the switch are deleted, and the switch broadcasts a large amount of data
packets, which might be listened to by unwanted users, resulting in security hazards. To avoid this, you
can configure mac-address timer no-aging for dynamic MAC address entries, so that dynamic MAC
address entries will not be aged out. This can reduce broadcasts and improve the stability and security
of the network.
Configuration procedure
To configure the aging timer for dynamic MAC address entries:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the aging timer for
dynamic MAC address
entries.
mac-address timer
{ aging seconds |
no-aging }
Optional.
The default setting is
300 seconds.
Configuring the MAC learning limit
Configuring the MAC learning limit on ports
To prevent the MAC address table from getting so large that the forwarding performance of the switch
degrades, you can limit the number of MAC addresses that can be learned on a port.
To configure the MAC learning limit on an Ethernet port, the Ethernet ports in a port group, or a Layer 2
aggregate interface: