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Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 5 Administering the Switch
Managing the MAC Address Table
Follow these guidelines when disabling MAC address learning:
• You can disable MAC address learning on a VLAN or on an Ethernet flow point (EFP)
service-instance bridge domain.
• Disable MAC address learning on a VLAN or bridge domain by entering the no mac address-table
learning {vlan vlan-id | bridge-domain domain-id} command.
• Use caution before disabling MAC address learning on a VLAN with a configured switch virtual
interface (SVI). The switch then floods all IP packets in the Layer 2 domain.
• We recommend that you disable MAC address learning only in VLANs with two ports. If you
disable MAC address learning on a VLAN with more than two ports, every packet entering the
switch is flooded in that VLAN domain.
Beginning in privileged EXEC mode, follow these steps to disable MAC address learning on a VLAN:
To reenable MAC address learning on a VLAN or bridge, use the default mac address-table learning
{vlan vlan-id | bridge-domain domain-id} global configuration command. You can also reenable MAC
address learning on a VLAN by entering the mac address-table learning {vlan vlan-id |
bridge-domain domain-id} global configuration command. The first (default) command returns to a
default condition and therefore does not appear in the output from the show running-config command.
The second command causes the configuration to appear in the show running-config privileged EXEC
command display.
This example shows how to disable MAC address learning on VLAN 200:
Switch(config)# no mac address-table learning vlan 200
You can display the MAC address learning status of all VLANs or a specified VLAN by entering the
show mac-address-table learning privileged EXEC command.
Displaying Address Table Entries
You can display the MAC address table by using one or more of the privileged EXEC commands
described in Table 5-4:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
no mac address-table learning {vlan
vlan-id | bridge-domain domain-id}
Disable MAC address learning on the specified VLAN or bridge domain.
Valid VLAN IDs 1 to 4094. Valid bridge domains are from 1 to 8000.
Step 3
end Return to privileged EXEC mode.
Step 4
show mac address-table learning [vlan
vlan-id]
Verify the configuration.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.
Table 5-4 Commands for Displaying the MAC Address Table
Command Description
show ip igmp snooping groups Displays the Layer 2 multicast entries for all VLANs or the specified VLAN.
show mac address-table address Displays MAC address table information for the specified MAC address.
show mac address-table aging-time Displays the aging time in all VLANs or the specified VLAN.
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