arp learning multicast enable (interface view)

Function

The arp learning multicast enable command enables an interface to learn ARP entries with multicast MAC addresses.

The undo arp learning multicast enable command disables an interface from learning ARP entries with multicast MAC addresses.

By default, if a device is globally enabled to learn ARP entries with multicast MAC addresses, this function is enabled on all the interfaces. If a device is globally disabled from learning ARP entries with multicast MAC addresses, this function is disabled on all the interfaces.

Format

arp learning multicast enable

undo arp learning multicast enable

Parameters

None

Views

Ethernet interface view, GE interface view, XGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, MultiGE interface view, Eth-Trunk interface view, VLANIF interface view, VBDIF interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

An IP address may map a multicast MAC address. In this case, a network administrator has to configure a static ARP entry. After a device is enabled to learn ARP entries with multicast MAC addresses, the device can generate dynamic ARP entries. This reduces a network administrator's workload and decreases network operation and maintenance costs.

Precautions

After a device is enabled to learn ARP entries with multicast MAC addresses, the device may be attacked by ARP attack packets with multicast MAC addresses.

To prevent the device from being attacked, multicast MAC address learning adopts the most precise matching rule:

When the function is enabled globally and on an interface, the configuration on the interface takes effect.
When the function is disabled on an interface, the global configuration takes effect.
When the function is disabled globally, the configuration on the interface takes effect.

If you run the undo arp learning multicast enable command on an interface when the function is enabled globally and on the interface, the global configuration takes effect and the function is still enabled. To completely disable the interface from learning ARP entries with multicast MAC addresses, run the arp learning multicast disable command on the interface.

Example

# Enable GigabitEthernet0/0/1 to learn ARP entries with multicast MAC addresses.

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] arp learning multicast enable