Displaying Address Table Entries - Cisco 3845 - Security Bundle Router Software Manual

Chapter 5 Administering the Switch
Follow these guidelines when disabling MAC address learning:
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Beginning in privileged EXEC mode, follow these steps to disable MAC address learning on a VLAN:
Command
Step 1
configure terminal
Step 2
no mac address-table learning {vlan
vlan-id | bridge-domain domain-id}
Step 3 end
Step 4 show mac address-table learning [vlan
vlan-id]
Step 5
copy running-config startup-config
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
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 Commands for Displaying the MAC Address Table
Command
show ip igmp snooping groups
show mac address-table address
show mac address-table aging-time
OL-23400-01
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.
Purpose
Enter global configuration mode.
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.
Return to privileged EXEC mode.
Verify the configuration.
(Optional) Save your entries in the configuration file.
a
ddress-table learning vlan 200
Table 5-4:
Description
Displays the Layer 2 multicast entries for all VLANs or the specified VLAN.
Displays MAC address table information for the specified MAC address.
Displays the aging time in all VLANs or the specified VLAN.
Cisco ME 3800X and 3600X Switch Software Configuration Guide
Managing the MAC Address Table
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