3Com Switch 7700 Configuration Manual page 340

332 C 11: S
HAPTER YSTEM
M
ANAGEMENT
Setting MAC Address Aging Time
Setting an appropriate aging time implements MAC address aging. Too long or
too short an aging time set by subscribers will cause the Ethernet switch to flood a
large amount of data packets. This affects the switch operation performance.
If aging time is set too long, the Ethernet switch stores a great number of
out-of-date MAC address tables. This consumes MAC address table resources and
the switch will not be able to update the MAC address table according to the
network change.
If aging time is set too short, the Ethernet switch may delete valid MAC address
table entries.
You can use the following commands to set the MAC address aging time for the
system.
Perform the following configuration in system view.
Table 18 Setting the MAC Address Aging Time for the System
Operation
Set the dynamic MAC address aging time
Restore the default MAC address aging time
In addition, this command takes effect on all the ports. However, the address
aging only functions on the dynamic addresses (the learned or configured as age
entries by the user).
By default, the aging-time is 300 seconds. With the no-aging parameter, the
command performs no aging on the MAC address entries.
Setting the Maximum MAC Addresses an Ethernet Port can Learn
Use the following command to set an amount limit on MAC addresses learned by
the Ethernet port. If the number of MAC addresses learned by this port exceeds
the value set by the user, this port will not learn MAC address.
Perform the following configuration in Ethernet port view.
Table 19 Setting an Amount Limit to the MAC Addresses Learned by the Ethernet Port
Operation
Set an amount limit to the MAC addresses
learned by the Ethernet port
Restore the default limit to the MAC
addresses learned by the Ethernet port
NOTE: If the count parameter is set to 0, the port is not permitted to learn MAC
address. By default, there is no limit to the amount of the MAC addresses that an
Ethernet port can learn. However, the number of MAC addresses a port can learn
is restricted by the size of the MAC address table.
Displaying and Debugging the MAC Address Table
Execute the display command in all views to display the MAC address table
configuration, and to verify the effect of the configuration.
Command
mac-address timer { aging age | no-aging }
undo mac-address timer aging-time
Command
mac-address max-mac-count count
undo mac-address max-mac-count