Cisco Systems A9014CFD manual No mac-address-table learning vlan vlan-id, Interface type slot/port

Chapter 8 Configuring Ethernet Virtual Connections

Configuring Other Features on EFPs

Disabling MAC Address Learning on an Interface or Bridge Domain

By default, MAC address learning is enabled on all interfaces and bridge domains or VLANs on the router. You can control MAC address learning on an interface or VLAN to manage the available MAC address table space by controlling which interfaces or VLANs can learn MAC addresses. When you disable MAC address learning for a BD/VLAN or interface, the router that receives packet from any source on the BD, VLAN or interface, the addresses are not learned. Since addresses are not learned, all IP packets floods into the Layer 2 domain.

Prerequisites

You can disable MAC address learning on a single VLAN ID from 2 to 4092 (for example, no mac-address-table learning vlan 10). If the MAC address learning is disabled for a VLAN or interface, the already learnt addresses for that VLAN or interface are immediately removed from the MAC address table. However, you cannot disable MAC learning for the reserved 4093, 4094, and 4095 VLAN IDs. If the VLAN ID that you enter is a reserved VLAN, the switch generates an error message and rejects the command.

•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.

Restrictions

•You cannot disable MAC address learning on a VLAN that is used internally by the router. VLAN ID 1 is used internally by the router. If the VLAN ID that you enter is an internal VLAN, the switch generates an error message and rejects the command.

Complete the following steps to disable MAC address learning on a VLAN:

SUMMARY STEPS

1.configure terminal

2.no mac-address-table learning {vlan vlan-id interface interface slot/port}

3.end

4.copy running-config startup-config

DETAILED STEPS

	Command or Action		Purpose
Step 1	configure terminal		Enters global configuration mode.
	Example:
	Router# configure terminal
Step 2	no mac-address-table learning {vlan vlan-id		Disable MAC address learning on an interface or on a
	interface type slot/port}		specified VLAN.
			vlan vlan-id—Specifies the VLAN ID which ranges from 2
	Example:		to 4094. It cannot be an internal VLAN or reserved VLAN.
	Router(config)# no mac-address-table learning		interface type slot/port—Specifies the location of the
	vlan 10		interface and its type.
		Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
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