05-Layer 2—LAN Switching Command Reference

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01-MAC address table commands
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01-MAC address table commands 75.52 KB

MAC address table commands

This document covers the configuration of static unicast MAC address entries and blackhole MAC address entries. For more information about configuring static multicast MAC address entries, see IGMP snooping and IPv6 multicast routing and forwarding in IP Multicast Configuration Guide. For more information about MAC address table configuration in VPLS, see MPLS Configuration Guide.

display mac-address

Use display mac-address to display MAC address entries.

Syntax

display mac-address [ mac-address [ vlan vlan-id ] | [ [ dynamic | static ] [ interface interface-type interface-number ] | blackhole ] [ vlan vlan-id ] [ count ] ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

mac-address: Specifies a MAC address in the format of H-H-H. When entering a MAC address, you can omit the leading zeros in each H section. For example, enter f-e2-1 for 000f-00e2-0001.

vlan vlan-id: Specifies a VLAN by its ID in the range of 1 to 4094.

dynamic: Displays dynamic MAC address entries.

static: Displays static MAC address entries.

interface interface-type interface-number: Specifies an interface by its type and number.

blackhole: Displays blackhole MAC address entries.

count: Displays only the number of MAC address entries that match all entry attributes you specify in the command. Detailed information about MAC address entries is not displayed. For example, you can use the display mac-address vlan 20 dynamic count command to display the number of dynamic entries for VLAN 20. If you do not specify an entry attribute, the command displays the number of entries in the MAC address table. If you do not specify this keyword, the command displays detailed information about the specified MAC address entries.

Usage guidelines

A MAC address entry includes a destination MAC address, an outgoing interface, and a VLAN ID.

If you do not specify any parameters, the command displays all MAC address entries.

This command displays dynamic MAC address entries for an aggregate interface only when the aggregate interface has a minimum of one Selected member port.

Examples

# Display MAC address entries for VLAN 100.

<Sysname> display mac-address vlan 100

MAC Address      VLAN ID    State            Port/Nickname            Aging

0001-0101-0101   100        Blackhole        GE0/0/1                  N

                                             GE0/0/2

0033-0033-0033   100        Blackhole        N/A                      N

0000-0000-0002   100        Static           GE0/0/3                  N

00e0-fc00-5829   100        Learned          GE0/0/4                  Y

# Display the number of MAC address entries.

<Sysname> display mac-address count

1 mac address(es) found.

Table 1 Command output

Field

Description

VLAN ID

ID of the VLAN to which the outgoing interface of the MAC address entry belongs.

State

MAC address entry state:

·     Static—Static MAC address entry.

·     Learned—Dynamic MAC address entry. Dynamic entries can be learned or manually configured.

·     Blackhole—Blackhole MAC address entry.

·     OpenFlow—MAC address entry for an OpenFlow instance.

·     Security—MAC address entry configured or learned by port security.

Port/Nickname

When the field displays an interface name, the field indicates the outgoing interface for packets that are destined for the MAC address. This field displays N/A for a blackhole MAC address entry.

When the field displays an interface name, the field indicates the outgoing interface for packets that are destined for the MAC address. This field displays N/A for a blackhole MAC address entry.

Aging

Whether the entry can age out:

·     Y—The entry can age out.

·     N—The entry never ages out.

mac address(es) found

Number of matching MAC address entries.

 

Related commands

mac-address

mac-address timer

display mac-address aging-time

Use display mac-address aging-time to display the aging timer for dynamic MAC address entries.

Syntax

display mac-address aging-time

Views

Any view

Predefined user roles

network-admin

network-operator

Examples

# Display the aging timer for dynamic MAC address entries.

<Sysname> display mac-address aging-time

MAC address aging time: 300s.

Related commands

mac-address timer

display mac-address mac-learning

Use display mac-address mac-learning to display the global MAC address learning status and the MAC learning status of the specified interface or all interfaces.

Syntax

display mac-address mac-learning [ interface interface-type interface-number ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, the command displays the global MAC address learning status and the MAC address learning status of all interfaces.

Examples

# Display the global MAC address learning status and the MAC learning status of all interfaces.

<Sysname> display mac-address mac-learning

Global MAC address learning status: Enabled.

 

Port                         Learning Status

GE0/0/1                     Enabled

GE0/0/2                     Enabled

Table 2 Command output

Field

Description

Global MAC address learning status

Global MAC address learning status:

·     Enabled.

·     Disabled.

Learning Status

MAC address learning status of an interface:

·     Enabled.

·     Disabled.

 

Related commands

mac-address mac-learning enable

mac-address (interface view)

Use mac-address to add or modify a MAC address entry on an interface.

Use undo mac-address to delete a MAC address entry on an interface.

Syntax

mac-address staticmac-address vlan vlan-id

undo mac-address  staticmac-address vlan vlan-id

Default

An interface is not configured with MAC address entries.

Views

Layer 2 Ethernet interface view

Predefined user roles

network-admin

Parameters

 

static: Specifies static MAC address entries.

mac-address: Specifies a MAC address in the format of H-H-H, excluding multicast, all-zero, and all-F MAC addresses. When entering a MAC address, you can omit the leading zeros in each H section. For example, enter f-e2-1 for 000f-00e2-0001. The MAC address cannot be the base MAC address.

vlan vlan-id: Specifies an existing VLAN to which the specified interface belongs. The value range for the vlan-id argument is 1 to 4094.

Usage guidelines

Typically, the device automatically builds the MAC address table by learning the source MAC addresses of incoming frames on each interface. However, you can manually configure static MAC address entries. For a MAC address, a manually configured static entry takes precedence over a dynamically learned entry. To improve the security for the user device connected to an interface, manually configure a static entry to bind the user device to the interface. Then, the frames destined for the user device (for example, Host A) are always sent out of the interface. Other hosts using the forged MAC address of Host A cannot obtain the frames destined for Host A.

The MAC address entry configuration cannot survive a reboot unless you save it. The dynamic MAC address entries, however, are lost upon reboot whether or not you save the configuration.

Examples

# Add a static entry for MAC address 000f-e201-0101 on GigabitEthernet 0/0/1 that belongs to VLAN 2.

<Sysname> system-view

[Sysname] interface gigabitethernet 0/0/1

[Sysname-GigabitEthernet0/0/1] mac-address static 000f-e201-0101 vlan 2

Related commands

display mac-address

mac-address (system view)

mac-address (system view)

Use mac-address to add or modify a MAC address entry.

Use undo mac-address to delete one or all MAC address entries.

Syntax

mac-address static mac-address interface interface-type interface-number vlan vlan-id

mac-address blackhole mac-address vlan vlan-id

undo mac-address [ static mac-address interface interface-type interface-number vlan vlan-id ]

undo mac-address [ blackhole | static ] [ mac-address ] vlan vlan-id

undo mac-address static interface interface-type interface-number

Default

The system is not configured with MAC address entries.

Views

System view

Predefined user roles

network-admin

Parameters

static: Specifies static MAC address entries.

blackhole: Specifies blackhole MAC address entries. Packets whose source or destination MAC addresses match blackhole MAC address entries are dropped.

mac-address: Specifies a MAC address in the format of H-H-H, excluding multicast, all-zero, and all-F MAC addresses. When entering a MAC address, you can omit the leading zeros in each H section. For example, enter f-e2-1 for 000f-00e2-0001. The MAC address cannot be the base MAC address.

vlan vlan-id: Specifies an existing VLAN to which the interface belongs. The value range for the vlan-id argument is 1 to 4094.

interface interface-type interface-number: Specifies an outgoing interface by its type and number.

Usage guidelines

You can use this command to configure the following types of MAC address entries:

·     Static entries.

For a MAC address, a manually configured static entry takes precedence over a dynamic entry. To improve the security for the user device connected to an interface, manually configure a static entry to bind the user device to the interface. Then, the frames destined for the user device (for example, Host A) are always sent out of the interface. Other hosts using the forged MAC address of Host A cannot obtain the frames destined for Host A.

·     Blackhole entries.

To drop frames with the specified source MAC addresses or destination MAC addresses, you can configure blackhole entries.

A static or blackhole entry can overwrite a dynamic entry, but not vice versa.

If you execute the undo mac-address command without specifying any parameters, this command deletes all unicast MAC address entries and static multicast MAC address entries.

·     You can delete all the MAC address entries (including unicast and static multicast MAC address entries) from the specified VLAN. You can also delete only one type (static or blackhole) of MAC address entries. You can single out an interface and delete the unicast MAC address entries on it, but not the static multicast MAC address entries.

The MAC address entry configuration cannot survive a reboot unless you save it. The dynamic MAC address entries, however, are lost upon reboot whether or not you save the configuration

Examples

# Add a blackhole entry for MAC address 000f-e201-0101. Then, all frames that are destined for this MAC address, which belongs to VLAN 2.

<Sysname> system-view

[Sysname] mac-address blackhole 000f-e201-0101 vlan 2

Related commands

display mac-address

mac-address (interface view)

mac-address mac-learning enable

Use mac-address mac-learning enable to enable MAC address learning globally or on an interface.

Use undo mac-address mac-learning enable to disable MAC address learning globally oron an interface.

Syntax

mac-address mac-learning enable

undo mac-address mac-learning enable

Default

MAC address learning is enabled.

Views

Layer 2 Ethernet interface view

Layer 2 aggregate interface view

Predefined user roles

network-admin

Usage guidelines

To prevent the MAC address table from becoming saturated, you can disable MAC address learning.

For example, a number of packets with different source MAC addresses reaching a device can affect the MAC address table update. To avoid such attacks, you can disable MAC address learning by following these guidelines:

·     You can disable MAC address learning on a per-interface basis. If you disable MAC address learning globally, MAC address learning is disabled for all interfaces. The device then stops learning MAC addresses and cannot dynamically update the MAC address table.

·     Because disabling MAC address learning can result in broadcast storms, enable broadcast storm suppression after you disable MAC address learning on an interface. For more information about broadcast storm suppression, see Interface Configuration Guide.

·     With MAC address learning enabled globally, you can disable MAC address learning for an interface.

·     After MAC address learning is disabled, existing dynamic MAC address entries can age out.

This command does not take effect on a VPLS VSI or VXLAN VSI. For information about VPLS VSIs, see MPLS Configuration Guide. For information about VXLAN VSIs, see VXLAN Configuration Guide.

Examples

# Disable MAC address learning globally.

<Sysname> system-view

[Sysname] undo mac-address mac-learning enable

# Disable MAC address learning on GigabitEthernet 0/0/1.

<Sysname> system-view

[Sysname] interface gigabitethernet 0/0/1

[Sysname-GigabitEthernet0/0/1] undo mac-address mac-learning enable

# Disable MAC address learning on Bridge-Aggregation 1.

<Sysname> system-view

[Sysname] interface bridge-aggregation 1

[Sysname-Bridge-Aggregation1] undo mac-address mac-learning enable

Related commands

display mac-address mac-learning

mac-address timer

Use mac-address timer to set the aging timer for dynamic MAC address entries.

Use undo mac-address timer to restore the default.

Syntax

mac-address timer { aging seconds | no-aging }

undo mac-address timer

Default

The default MAC aging timer is 300 seconds.

Views

System view

Predefined user roles

network-admin

Parameters

aging seconds: Specifies an aging timer for dynamic MAC address entries, in seconds. The value range for the seconds argument is10 to 630.

no-aging: Configures dynamic MAC address entries not to age.

Usage guidelines

To set the aging timer appropriately, follow these guidelines:

·     A long aging interval causes the MAC address table to retain outdated entries and fail to accommodate the most recent network changes.

·     A short aging interval results in removal of valid entries. Then, unnecessary broadcast packets appear and affect device performance.

Examples

# Set the aging time to 500 seconds for dynamic MAC address entries.

<Sysname> system-view

[Sysname] mac-address timer aging 500

Related commands

display mac-address aging-time