H3C S7500X Series User manual

H3C S7500X Switch Series
Comware 7 Layer 2—LAN Switching
Configuration Guide
New H3C Technologies Co., Ltd.
http://www.h3c.com
Software version: Release 7577P04 and later versions
Document version: 6W100-20190315

Copyright © 2019, New H3C Technologies Co., Ltd. and its licensors
All rights reserved
No part of this manual may be reproduced or transmitted in any form or by any means without prior written
consent of New H3C Technologies Co., Ltd.
Trademarks
Except for the trademarks of New H3C Technologies Co., Ltd., any trademarks that may be mentioned in this
document are the property of their respective owners.
Notice
The information in this document is subject to change without notice. All contents in this document, including
statements, information, and recommendations, are believed to be accurate, but they are presented without
warranty of any kind, express or implied. H3C shall not be liable for technical or editorial errors or omissions
contained herein.

Preface
This configuration guide covers Layer 2 technologies and features used on a LAN switched network.
This preface includes the following topics about the documentation:
•Audience.
•Conventions.
•Documentation feedback.
Audience
This documentation is intended for:
•Network planners.
•Field technical support and servicing engineers.
•Network administrators working with the S7500X switch series.
Conventions
The following information describes the conventions used in the documentation.
Command conventions
Convention Description
Boldface Bold text represents commands and keywords that you enter literally as shown.
Italic Italic text represents arguments that you replace with actual values.
[ ] Square brackets enclose syntax choices (keywords or arguments) that are optional.
{ x | y | ... }
Braces enclose a set of required syntax choices separated by vertical bars, from which
you select one.
[ x | y | ... ]
Square brackets enclose a set of optional syntax choices separated by vertical bars,
from which you select one or none.
{ x | y | ... } *
Asterisk marked braces enclose a set of required syntax choices separated by vertical
bars, from which you select a minimum of one.
[ x | y | ... ] *
Asterisk marked square brackets enclose optional syntax choices separated by vertical
bars, from which you select one choice, multiple choices, or none.
&<1-n> The argument or keyword and argument combination before the ampersand (&) sign
can be entered 1 to n times.
# A line that starts with a pound (#) sign is comments.
GUI conventions
Convention Description
Boldface Window names, button names, field names, and menu items are in Boldface. For
example, the New User window opens; click OK.
> Multi-level menus are separated by angle brackets. For example, File > Create >
Folder.

Symbols
Convention Description
WARNING! An alert that calls attention to important information that if not understood or followed
can result in personal injury.
CAUTION: An alert that calls attention to important information that if not understood or followed
can result in data loss, data corruption, or damage to hardware or software.
IMPORTANT: An alert that calls attention to essential information.
NOTE: An alert that contains additional or supplementary information.
TIP: An alert that provides helpful information.
Network topology icons
Convention Description
Represents a generic network device, such as a router, switch, or firewall.
Represents a routing-capable device, such as a router or Layer 3 switch.
Represents a generic switch, such as a Layer 2 or Layer 3 switch, or a router that
supports Layer 2 forwarding and other Layer 2 features.
Represents an access controller, a unified wired-WLAN module, or the access
controller engine on a unified wired-WLAN switch.
Represents an access point.
Represents a wireless terminator unit.
Represents a wireless terminator.
Represents a mesh access point.
Represents omnidirectional signals.
Represents directional signals.
Represents a security product, such as a firewall, UTM, multiservice security
gateway, or load balancing device.
Represents a security module, such as a firewall, load balancing, NetStream, SSL
VPN, IPS, or ACG module.
Examples provided in this document
Examples in this document might use devices that differ from your device in hardware model,
configuration, or software version. It is normal that the port numbers, sample output, screenshots,
and other information in the examples differ from what you have on your device.
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Documentation feedback
You can e-mail your comments about product documentation to [e-mail].
We appreciate your comments.

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Contents
Configuring the MAC address table······················································1
Overview··································································································································1
How a MAC address entry is created·······················································································1
Types of MAC address entries ·······························································································1
MAC address table configuration task list························································································2
Configuring MAC address entries··································································································3
Configuration guidelines ·······································································································3
Adding or modifying a static or dynamic MAC address entry globally··············································3
Adding or modifying a static or dynamic MAC address entry on an interface ····································3
Adding or modifying a blackhole MAC address entry···································································4
Adding or modifying a multiport unicast MAC address entry··························································4
Disabling MAC address learning ···································································································5
Disabling global MAC address learning····················································································5
Disabling MAC address learning on interfaces···········································································6
Disabling MAC address learning on a VLAN··············································································6
Setting the aging timer for dynamic MAC address entries ···································································6
Setting the MAC learning limit·······································································································7
Configuration restrictions and guidelines ··················································································7
Setting the MAC learning limit on an interface············································································7
Setting the MAC learning limit for a VLAN·················································································8
Configuring the unknown frame forwarding rule after the MAC learning limit is reached ····························8
Configuration restrictions and guidelines ··················································································8
Configuring the device to forward unknown frames after the MAC learning limit on an interface is reached
·······································································································································8
Configuring the device to forward unknown frames after the MAC learning limit for a VLAN is reached··9
Assigning MAC learning priority to interfaces ···················································································9
Enabling MAC address synchronization························································································10
Configuring MAC address move notifications and suppression ··························································11
Enabling ARP fast update for MAC address moves·········································································12
Disabling static source check······································································································13
Enabling SNMP notifications for the MAC address table···································································14
Displaying and maintaining the MAC address table ·········································································14
MAC address table configuration example·····················································································15
Network requirements ········································································································15
Configuration procedure ·····································································································15
Verifying the configuration···································································································15
Configuring MAC Information····························································16
Enabling MAC Information ·········································································································16
Configuring the MAC Information mode ························································································16
Setting the MAC change notification interval ··················································································17
Setting the MAC Information queue length ····················································································17
MAC Information configuration example························································································17
Network requirements ········································································································17
Configuration restrictions and guidelines ················································································17
Configuration procedure ·····································································································18

1
Configuring the MAC address table
Overview
An Ethernet device uses a MAC address table to forward frames. A MAC address entry includes a
destination MAC address, an outgoing interface, and a VLAN ID. When the device receives a frame,
it uses the destination MAC address of the frame to look for a match in the MAC address table.
•The device forwards the frame out of the outgoing interface in the matching entry if a match is
found.
•The device floods the frame in the VLAN of the frame if no match is found.
How a MAC address entry is created
The entries in the MAC address table include entries automatically learned by the device and entries
manually added.
MAC address learning
The device can automatically populate its MAC address table by learning the source MAC addresses
of incoming frames on each interface.
The device performs the following operations to learn the source MAC address of incoming packets:
1. Checks the source MAC address (for example, MAC-SOURCE) of the frame.
2. Looks up the source MAC address in the MAC address table.
{The device updates the entry if an entry is found.
{The device adds an entry for MAC-SOURCE and the incoming port if no entry is found.
When the device receives a frame destined for MAC-SOURCE after learning this source MAC
address, the device performs the following operations:
1. Finds the MAC-SOURCE entry in the MAC address table.
2. Forwards the frame out of the port in the entry.
The device performs the learning process for each incoming frame with an unknown source MAC
address until the table is fully populated.
Manually configuring MAC address entries
Dynamic MAC address learning does not distinguish between illegitimate and legitimate frames,
which can invite security hazards. When HostAis connected to portA, a MAC address entry will be
learned for the MAC address of Host A (for example, MAC A). When an illegal user sends frames
with MAC A as the source MAC address to port B, the device performs the following operations:
1. Learns a new MAC address entry with port B as the outgoing interface and overwrites the old
entry for MAC A.
2. Forwards frames destined for MAC A out of port B to the illegal user.
As a result, the illegal user obtains the data of Host A. To improve the security for Host A, manually
configure a static entry to bind Host Ato portA. Then, the frames destined for HostAare always sent
out of port A. Other hosts using the forged MAC address of Host Acannot obtain the frames destined
for Host A.
Types of MAC address entries
A MAC address table can contain the following types of entries:

2
•Static entries—A static entry is manually added to forward frames with a specific destination
MAC address out of the associated interface, and it never ages out.A static entry has higher
priority than a dynamically learned one.
•Dynamic entries—A dynamic entry can be manually configured or dynamically learned to
forward frames with a specific destination MAC address out of the associated interface. A
dynamic entry might age out. A manually configured dynamic entry has the same priority as a
dynamically learned one.
•Blackhole entries—Ablackhole entry is manually configured and never ages out. A blackhole
entry is configured for filtering out frames with a specific source or destination MAC address.
For example, to block all frames destined for or sourced from a user, you can configure the
MAC address of the user as a blackhole MAC address entry. A blackhole entry has higher
priority than a dynamically learned one.
•Multiport unicast entries—Amultiport unicast entry is manually added to send frames with a
specific unicast destination MAC address out of multiple ports, and it never ages out. Amultiport
unicast entry has higher priority than a dynamically learned one.
A static, blackhole, or multiport unicast MAC address entry can overwrite a dynamic MAC address
entry, but not vice versa. A static entry, a blackhole entry, and a multiport unicast entry cannot
overwrite one another.
MAC address table configuration task list
The configuration tasks discussed in the following sections can be performed in any order.
This document covers only the configuration of unicast MAC address entries, including static,
dynamic, blackhole, and multiport unicast MAC address entries. For information about configuring
static multicast MAC address entries, see IP Multicast Configuration Guide. For information about
MAC address table configuration in VPLS, see MPLS Configuration Guide.
To configure the MAC address table, perform the following tasks:
Tasks at a glance
(Optional.) Configuring MAC address entries
•Adding or modifying a static or dynamic MAC address entry globally
•Adding or modifying a static or dynamic MAC address entry on an interface
•Adding or modifying a blackhole MAC address entry
•Adding or modifying a multiport unicast MAC address entry
(Optional.) Disabling MAC address learning
(Optional.) Setting the aging timer for dynamic MAC address entries
(Optional.) Setting the MAC learning limit
(Optional.) Configuring the unknown frame forwarding rule after the MAC learning limit is reached
(Optional.) Assigning MAC learning priority to interfaces
(Optional.) Enabling MAC address synchronization
(Optional.) Configuring MAC address move notifications and suppression
(Optional.) Enabling ARP fast update for MAC address moves
(Optional.) Disabling static source check
(Optional.) Enabling SNMP notifications for the MAC address table

3
Configuring MAC address entries
Configuration guidelines
•You cannot add a dynamic MAC address entry if a learned entry already exists with a different
outgoing interface for the MAC address.
•The manually configured static, blackhole, and multiport unicast MAC address entries cannot
survive a reboot if you do not save the configuration. The manually configured dynamic MAC
address entries are lost upon reboot whether or not you save the configuration.
A frame whose source MAC address matches different types of MAC address entries is processed
differently.
Type Description
Static MAC address entry Forwards the frame according to the destination MAC address regardless of
whether the frame's ingress interface is the same as that in the entry.
Multiport unicast MAC
address entry
•Learns the MAC address of the frame and generates a dynamic MAC
address entry, but the generated dynamic MAC address entry does not
take effect.
•Forwards the frame based on the multiport unicast MAC address entry.
Blackhole MAC address
entry Drops the frame.
Dynamic MAC address
entry
•Learns the MAC address of the frames received on a different interface
from that in the entry and overwrites the original entry.
•Forwards the frame received on the same interface as that in the entry
and updates the aging timer for the entry.
Adding or modifying a static or dynamic MAC address entry
globally
Step Command Remarks
1. Enter system view. system-view N/A
2. Add or modify a static or
dynamic MAC address entry.
mac-address { dynamic |static }
mac-address interface
interface-type interface-number
vlan vlan-id
By default, no MAC address entry
is configured globally.
Make sure you have created the
VLAN and assigned the interface
to the VLAN.
Adding or modifying a static or dynamic MAC address entry
on an interface
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
•Enter Layer 2 Ethernet
interface view:
interface interface-type
interface-number N/A

4
Step Command Remarks
•
Enter Layer 2 aggregate
interface view:
interface
bridge-aggregation
interface-number
3. Add or modify a static or
dynamic MAC address entry. mac-address { dynamic | static }
mac-address vlan vlan-id
By default, no MAC address entry
is configured on the interface.
Make sure you have created the
VLAN and assigned the interface
to the VLAN.
Adding or modifying a blackhole MAC address entry
Step Command Remarks
1. Enter system view. system-view N/A
2. Add or modify a blackhole
MAC address entry. mac-address blackhole
mac-address vlan vlan-id
By default, no blackhole MAC
address entry is configured.
Make sure you have created the
VLAN.
Adding or modifying a multiport unicast MAC address entry
You can configure a multiport unicast MAC address entry to associate a unicast destination MAC
address with multiple ports. The frame with a destination MAC address matching the entry is sent out
of multiple ports.
For example, in NLB unicast mode (see Figure 1):
•All servers within a cluster uses the cluster's MAC address as their own address.
•Frames destined for the cluster are forwarded to every server in the group.
In this case, you can configure a multiport unicast MAC address entry on the device connected to the
server group. Then, the device forwards the frame destined for the server group to every server
through all ports connected to the servers within the cluster.
Figure 1 NLB cluster
You can configure a multiport unicast MAC address entry globally or on an interface.

5
Configuring a multiport unicast MAC address entry globally
Step Command Remarks
1. Enter system view. system-view N/A
2. Add or modify a multiport
unicast MAC address entry. mac-address multiport
mac-address interface
interface-list vlan vlan-id
By default, no multiport unicast
MAC address entry is configured
globally.
Make sure you have created the
VLAN and assigned the interface
to the VLAN.
Configuring a multiport unicast MAC address entry on an interface
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
•Enter Layer 2 Ethernet
interface view:
interface interface-type
interface-number
•Enter Layer 2 aggregate
interface view:
interface
bridge-aggregation
interface-number
N/A
3. Add the interface to a
multiport unicast MAC
address entry. mac-address multiport
mac-address vlan vlan-id
By default, no multiport unicast
MAC address entry is configured
on the interface.
Make sure you have created the
VLAN and assigned the interface
to the VLAN.
Disabling MAC address learning
MAC address learning is enabledby default. To prevent the MAC address table from being saturated
when the device is experiencing attacks, disable MAC address learning. For example, you can
disable MAC address learning to prevent the device from beingattacked by a largeamount of frames
with different source MAC addresses.
After MAC address learning is disabled, the device immediately deletes existing dynamic MAC
address entries.
Disabling global MAC address learning
After global MAC address learning is disabled, the device stops learning MAC addresses.
Global MAC address learning 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.
To disable global MAC address learning:
Step Command Remarks
1. Enter system view. system-view N/A
2. Disable global MAC address undo mac-address By default, global MAC address

6
Step Command Remarks
learning. mac-learning enable learning is enabled.
Disabling MAC address learning on interfaces
When global MAC address learning is enabled, you can disable MAC address learning on a single
interface.
To disable MAC address learning on an interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
•Enter Layer 2 Ethernet interface
view:
interface interface-type
interface-number
•Enter Layer 2 aggregate
interface view:
interface bridge-aggregation
interface-number
N/A
3. Disable MAC address
learning on the interface. undo mac-address mac-learning
enable
By default, MAC address
learning on the interface is
enabled.
Disabling MAC address learning on a VLAN
When global MAC address learning is enabled, you can disable MAC address learning on a
per-VLAN basis.
To disable MAC address learning on a VLAN:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable global MAC address
learning. mac-address mac-learning
enable By default, global MAC address
learning is enabled.
3. Enter VLAN view. vlan vlan-id N/A
4. Disable MAC address
learning on the VLAN. undo mac-address
mac-learning enable By default, MAC address learning
on the VLAN is enabled.
Setting the aging timer for dynamic MAC address
entries
For security and efficient use of table space, the MAC address table uses an aging timer for each
dynamic MAC address entry. If a dynamic MAC address entry is not updated before the aging timer
expires, the device deletesthe entry. This aging mechanism ensures that the MAC address table can
promptly update to accommodate latest network topology changes.
A stable network requires a longer aging interval, and an unstable network requires a shorter aging
interval.

7
An aging interval that is too long might cause the MAC address table to retain outdated entries. As a
result, the MAC address table resources might be exhausted, and the MAC address table might fail
to update its entries to accommodate the latest network changes.
An interval that is too short might result in removal of valid entries, which would cause unnecessary
floods and possibly affect the device performance.
To reduce floods on a stable network, set a long aging timer or disable the timer to prevent dynamic
entries from unnecessarily aging out. Reducing floods improves the network performance. Reducing
flooding also improves the security because it reduces the chances for a data frame to reach
unintended destinations.
To set the aging timer for dynamic MAC address entries:
Step Command Remarks
1. Enter system view. system-view N/A
2. Set the aging timer for
dynamic MAC address
entries. mac-address timer { aging
seconds | no-aging }
The default setting is 300
seconds.
The no-aging keyword disables
the aging timer.
Setting the MAC learning limit
Configuration restrictions and guidelines
In an IRF 3.1 system, interfaces and VLANs on PEXs do not support this feature. For more
information about PEXs, see Virtual Technologies Configuration Guide.
The MAC address learning limit does not take manually configured dynamic MAC addresses into
account.
This feature does not take effect when MAC-based VLANs or voice VLANs are configured or MAC
authentication is performed. For more information about MAC-based VLANs and voice VLANs, see
"Configuring VLANs" and "Configuring voice VLANs." For more information about MAC
authentication, see Security Configuration Guide.
For the MAC learning limit feature to function correctly, do not configure this feature in both interface
view and VLAN view.
If you configure this feature in the view of a VLAN, only basic VLAN commands and port-based
VLAN commands are supported on the VLAN. For more information, see VLANs in Layer 2—LAN
Switching Command Reference.
Setting the MAC learning limit on an interface
This feature limits the MAC address table size. A large MAC address table will degrade forwarding
performance.
If you set the MAC learning limit on a member port of an aggregation group, the setting takes effect
only after the member port is removed from the aggregation group.
To set the MAC learning limit on an interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Layer 2 Ethernet
interface view. interface interface-type
interface-number N/A

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Step Command Remarks
3. Set the MAC learning limit on
the interface. mac-address max-mac-count
count
By default, the number of MAC
addresses that can be learned on
an interface is not limited.
Setting the MAC learning limit for a VLAN
You can limit the number of MAC addresses that can be learned for a VLAN.
To configure the MAC learning limit for a VLAN:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter VLAN view. vlan vlan-id N/A
3. Set the MAC leaning limit for
the VLAN. mac-address max-mac-count
count By default, no MAC learning limit
is set for a VLAN.
Configuring the unknown frame forwarding rule
after the MAC learning limit is reached
You can enable or disable forwarding of unknown frames after the MAC learning limit is reached.
In this document, unknown frames refer to frames whose source MAC addressesare not in the MAC
address table.
Configuration restrictions and guidelines
For this feature to function correctly, do not configure this feature in both interface view and VLAN
view.
If you configure this feature in the view of a VLAN, only basic VLAN commands and port-based
VLAN commands are supported on the VLAN. For more information, see VLANs in Layer 2—LAN
Switching Command Reference.
Configuring the device to forward unknown frames after the
MAC learning limit on an interface is reached
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
•Enter Layer 2 Ethernet
interface view.
interface interface-type
interface-number
•Enter Layer 2 aggregate
interface view.
interface
bridge-aggregation
interface-number
N/A

9
Step Command Remarks
3. Configure the device to
forward unknown frames
received on the interface
after the MAC learning limit
on the interface is reached.
mac-address max-mac-count
enable-forwarding
By default, the device can forward
unknown frames received on an
interface after the MAC learning
limit on the interface is reached.
You cannot use the undo
mac-address max-mac-count
enable-forwarding command on
Layer 2 aggregate interfaces.
Configuring the device to forward unknown frames after the
MAC learning limit for a VLAN is reached
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter VLAN view. vlan vlan-id N/A
3. Configure the device to
forward unknown frames
received on interfaces in the
VLAN after the MAC learning
limit for the VLAN is reached.
mac-address max-mac-count
enable-forwarding
By default, the device can forward
unknown frames received on
interfaces in a VLAN after the
MAC learning limit for the VLAN is
reached.
Assigning MAC learning priority to interfaces
The MAC learning priority mechanism assigns either low priority or high priority to an interface. An
interface with high priority can learn MAC addresses as usual. However, an interface with low priority
is not allowed to learn MAC addresses already learned on a high-priority interface.
The MAC learning priority mechanism can help defend your network against MAC address spoofing
attacks. In a network that performs MAC-based forwarding, an upper layer device MAC address
might be learned by a downlink interface because of a loop or attack to the downlink interface. To
avoid this issue, perform the following tasks:
•Assign high MAC learning priority to an uplink interface.
•Assign low MAC learning priority to a downlink interface.
To assign MAC learning priority to an interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
•Enter Layer 2 Ethernet interface
view:
interface interface-type
interface-number
•Enter Layer 2 aggregate
interface view:
interface bridge-aggregation
interface-number
N/A
3. Assign MAC learning priority mac-address mac-learning priority By default, low MAC learning

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Step Command Remarks
to the interface. { high | low } priority is used.
Enabling MAC address synchronization
(In standalone mode.) To avoid unnecessary floods and improve forwarding speed, make sure all
cards have the same MAC address table. After you enable MAC address synchronization, each card
advertises learned MAC address entries to other cards.
(In IRF mode.) To avoid unnecessary floods and improve forwarding speed, make sure all cards
have the same MAC address table. After you enable MAC address synchronization, each card
advertises learned MAC address entries to other cards of all member devices.
As shown in Figure 2:
•Device A and Device B form an IRF fabric enabled with MAC address synchronization.
•Device A and Device B connect to AP C and AP D, respectively.
When Client A associates with AP C, Device A learns a MAC address entry for Client A and
advertises it to Device B.
Figure 2 MAC address tables of devices when Client A accesses AP C
When Client A roams to AP D, Device B learns a MAC address entry for Client A. Device B
advertises it to Device A to ensure service continuity for Client A, as shown in Figure 3.

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Figure 3 MAC address tables of devices when Client A roams to AP D
To enable MAC address synchronization:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable MAC address
synchronization. mac-address mac-roaming
enable By default, MAC address
synchronization is disabled.
Configuring MAC address move notifications and
suppression
The outgoing interface for a MAC address entry learned on interface A is changed to interface B
when the following conditions exist:
•Interface B receives a packet with the MAC address as the source MAC address.
•Interface B belongs to the same VLAN as interfaceA.
In this case, the MAC address is moved from interface A to interface B, and a MAC address move
occurs.
The MAC address move notifications feature enables the device to output MAC address move logs
when MAC address moves are detected.
If a MAC address is continuously moved between the two interfaces, Layer 2 loops might occur. To
detect and locate loops, you can view the MAC address move information. To display the MAC
address move records after the device is started, use the display mac-address mac-move
command.
If the system detects that MAC address moves occur frequently on an interface, you can configure
MAC address move suppression to shut the interface down. The interface automatically goes up
after a suppression interval. Or, you can manually bring up the interface.
To configure MAC address move notifications and MAC address move suppression:

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Step Command Remarks
1. Enter system view. system-view N/A
2. Enable MAC address move
notifications and optionally
specify a MAC move
detection interval.
mac-address notification
mac-move [ interval interval ]
By default, MAC address move
notifications are disabled.
If you do not specify a detection
interval, the default setting of 1
minute is used.
After you execute this command, the
system sends only log messages to
the information center module. If the
device is also configured with the
snmp-agent trap enable
mac-address command, the
system also sends SNMP
notifications to the SNMP module.
3. (Optional.) Set MAC
address move suppression
parameters.
mac-address notification
mac-move suppression
{ interval interval | threshold
threshold }
By default, the suppression interval
is 30 seconds, and the suppression
threshold is 3.
4. Enter interface view.
•Enter Layer 2 Ethernet
interface view:
interface interface-type
interface-number
•Enter Layer 2 aggregate
interface view:
interface
bridge-aggregation
interface-number
N/A
5. Enable MAC address move
suppression. mac-address notification
mac-move suppression By default, MAC address move
suppression is disabled.
Enabling ARP fast update for MAC address
moves
ARP fast update for MAC address moves allows the device to update an ARP entry immediately after
the outgoing interface for a MAC address changes. This feature ensures data connection without
interruption.
As shown in Figure 4, a mobile user laptop accesses the network by connecting to AP 1 or AP 2.
When the AP to which the user connects changes, the switch updates the ARP entry for the user
immediately after it detects a MAC address move.

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Figure 4 ARP fast update application scenario
To enable ARP fast update for MAC address moves:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable ARP fast update for
MAC address moves. mac-address mac-move
fast-update By default, ARP fast update for
MAC address moves is disabled.
Disabling static source check
By default, the static source check feature is enabled on an interface. The check identifies whether a
received frame meets the following conditions:
•The source MAC address of the frame matches a static MAC address entry.
•The incoming interface of the frame is different from the outgoing interface in the entry.
If the frame meets both conditions, the device drops the frame.
When this feature is disabled, the device does not perform the check for a received frame. It can
forward the frame whether or not the frame meets the conditions.
To correctly forward traffic sourced from the MAC address of a VLAN interface, you must disable the
static source check feature on the Layer 2 interfaces in the VLAN.
To disable the static source check feature:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
•Enter Layer 2 Ethernet interface
view:
interface interface-type
interface-number
•Enter Layer 2 aggregate
interface view:
interface bridge-aggregation
interface-number
N/A
3. Disable the static source
check feature. undo mac-address static
source-check enable By default, the static source
check feature is enabled.

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Enabling SNMP notifications for the MAC address
table
To report critical MAC address move events to an NMS, enable SNMP notifications for the MAC
address table. For MAC address move event notifications to be sent correctly, you must also
configure SNMP on the device.
When SNMP notifications are disabled for the MAC address table, the device sends the generated
logs to the information center. To display the logs, configure the log destination and output rule
configuration in the information center.
For more information about SNMP and information center configuration, see the network
management and monitoring configuration guide for the device.
To enable SNMP notifications for the MAC address table:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable SNMP
notifications for the
MAC address table. snmp-agent trap enable
mac-address [mac-move ]
By default, SNMP notifications are enabled
for the MAC address table.
When SNMP notifications are disabled for the
MAC address table, syslog messages are
sent to notify important events on the MAC
address table module.
Displaying and maintaining the MAC address
table
Execute display commands in any view.
Task Command
Display MAC address table
information.
display mac-address [ mac-address [ vlan vlan-id ] | [ [ dynamic |
static ] [ interface interface-type interface-number ] | blackhole |
multiport ] [ vlan vlan-id ] [ count ] ]
Display the aging timer for dynamic
MAC address entries. display mac-address aging-time
Display the system or interface MAC
address learning state. display mac-address mac-learning [ interface interface-type
interface-number ]
Display MAC address statistics. display mac-address statistics
(In standalone mode.) Display the
MAC address move records. display mac-address mac-move [ slot slot-number ]
(In IRF mode.) Display the MAC
address move records. display mac-address mac-move [ chassis chassis-number slot slot-number ]