H3C Technologies H3C S5560 Series Switches - Manual (Page 43)

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To disable MAC address learning on a VLAN:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable global MAC address
learning.
mac-address mac-learning enable
By default, global MAC address
learning is enabled.
3. Enter VLAN view. vlan vlan-id N/A
4. Disable MAC address
learning on the VLAN.
undo mac-address mac-learning
enable By default, MAC address learning
on the VLAN is enabled.
Configuring the aging timer for dynamic MAC
address entries
For security and efficient use of table space, the MAC address table uses an aging timer for each
dynamic MAC address entry. If a dynamic MAC address entry is not updated before the aging timer
expires, the device deletes the entry. This aging mechanism ensures that the MAC address table can
promptly update to accommodate latest network topology changes.
A stable network requires a longer aging interval, and an unstable network requires a shorter aging
interval.
An aging interval that is too long might cause the MAC address table to retain outdated entries. As a
result, the MAC address table resources might be exhausted, and the MAC address table might fail to
update to accommodate the latest network changes.
An interval that is too short might result in removal of valid entries, which would cause unnecessary
floods and possibly affect the device performance.
To reduce floods on a stable network, set a long aging timer or disable the timer to prevent dynamic
entries from unnecessarily aging out. Reducing floods improves the network performance. Reducing
flooding also improves the security because it reduces the chances for a data frame to reach unintended
destinations.
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 }
By default, the aging timer for
dynamic MAC address entries is
300 seconds
The no-aging keyword disables the
aging timer.
Configuring the MAC learning limit on an interface
This feature limits the MAC address table size. A large MAC address table will degrade forwarding
performance..