04-Network Connectivity

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09-ARP commands
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ARP commands

arp check enable

Use arp check enable to enable dynamic ARP entry check.

Use undo arp check enable to disable dynamic ARP entry check.

Syntax

arp check enable

undo arp check enable

Default

Dynamic ARP entry check is enabled.

Views

System view

Predefined user roles

network-admin

Usage guidelines

Dynamic ARP entry check disables a device from supporting dynamic ARP entries with multicast MAC addresses. The device cannot learn dynamic ARP entries containing multicast MAC addresses. You cannot manually add static ARP entries that contain multicast MAC addresses.

When dynamic ARP entry check is disabled, ARP entries containing multicast MAC addresses are supported. The device can learn dynamic ARP entries containing multicast MAC addresses obtained from the ARP packets sourced from a unicast MAC address. You can also manually add static ARP entries containing multicast MAC addresses.

Examples

# Enable dynamic ARP entry check.

<Sysname> system-view

[Sysname] arp check enable

arp check log enable

Use arp check log enable to enable the ARP logging feature.

Use undo arp check log enable to disable the ARP logging feature.

Syntax

arp check log enable

undo arp check log enable

Default

ARP logging is disabled.

Views

System view

Predefined user roles

network-admin

Usage guidelines

This feature enables a device to log ARP events when ARP cannot resolve IP addresses correctly. The log information helps administrators locate and solve problems. The device can log the following ARP events:

·     On a proxy ARP-disabled interface, the target IP address of a received ARP packet is not one of the following IP addresses:

¡     The IP address of the receiving interface.

¡     The virtual IP address of the VRRP group.

¡     The public IP address after NAT.

·     The sender IP address of a received ARP reply conflicts with one of the following IP addresses:

¡     The IP address of the receiving interface.

¡     The virtual IP address of the VRRP group.

¡     The public IP address after NAT.

The device sends ARP log messages to the information center. You can use the info-center source command to specify the log output rules for the information center. For more information about information center, see System Management Configuration Guide.

The device can generate a large number of ARP logs. To conserve system resources, enable ARP logging only when you are auditing or troubleshooting ARP events.

Examples

# Enable ARP logging.

<Sysname> system-view

[Sysname] arp check log enable

arp max-learning-num

Use arp max-learning-num to set the dynamic ARP learning limit for an interface.

Use undo arp max-learning-num to restore the default.

Syntax

arp max-learning-num max-number

undo arp max-learning-num

Default

An interface can learn a maximum of 816 dynamic ARP entries.

Views

Layer 2 Ethernet interface view

Layer 2 aggregate interface view

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Parameters

max-number: Specifies the maximum number of dynamic ARP entries for an interface. The value range for this argument is 0 to 816.

Usage guidelines

An interface can dynamically learn ARP entries. To prevent an interface from holding too many ARP entries, you can set the maximum number of dynamic ARP entries that the interface can learn. When the maximum number is reached, the interface stops learning ARP entries.

When the number argument is set to 0, the interface is disabled from learning dynamic ARP entries.

Examples

# Specify VLAN-interface 40 to learn a maximum of 10 dynamic ARP entries.

<Sysname> system-view

[Sysname] interface vlan-interface 40

[Sysname-Vlan-interface40] arp max-learning-num 10

# Specify GigabitEthernet 1/0/1 to learn a maximum of 10 dynamic ARP entries.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] arp max-learning-num 10

# Specify Layer 2 aggregate interface Bridge-Aggregation 1 to learn a maximum of 10 dynamic ARP entries.

<Sysname> system-view

[Sysname] interface bridge-aggregation 1

[Sysname-Bridge-Aggregation1] arp max-learning-num 10

# Specify Layer 3 aggregate interface Route-Aggregation 1 to learn a maximum of 10 dynamic ARP entries.

<Sysname> system-view

[Sysname] interface route-aggregation 1

[Sysname-Route-Aggregation1] arp max-learning-num 10

arp max-learning-number

Use arp max-learning-number to set the dynamic ARP learning limit for a device.

Use undo arp max-learning-number to restore the default.

Syntax

arp max-learning-number max-number

undo arp max-learning-number

Default

The device can learn a maximum of 816 dynamic ARP entries.

Views

System view

Predefined user roles

network-admin

Parameters

max-number: Specifies the maximum number of dynamic ARP entries for a device. The value range for this argument is 0 to 816.

Usage guidelines

A device can dynamically learn ARP entries. To prevent a device from holding too many ARP entries, you can set the maximum number of dynamic ARP entries that the device can learn. When the maximum number is reached, the device stops learning ARP entries.

When the number argument is set to 0, the device is disabled from learning dynamic ARP entries.

Examples

# Set the ARP learning limit to 64 for slot 1.

<Sysname> system-view

[Sysname] arp max-learning-number 64 slot 1

arp static

Use arp static to configure a static ARP entry.

Use undo arp to delete an ARP entry.

Syntax

arp static ip-address mac-address [ vlan-id interface-type interface-number ]

undo arp ip-address

Default

No static ARP entries exist.

Views

System view

Predefined user roles

network-admin

Parameters

ip-address: Specifies an IP address for the static ARP entry.

mac-address: Specifies a MAC address for the static ARP entry, in the format of H-H-H.

vlan-id: Specifies the ID of a VLAN to which the static ARP entry belongs. The value range is 1 to 4094.

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

Usage guidelines

A static ARP entry is manually configured and maintained. It does not age out and cannot be overwritten by any dynamic ARP entry.

Static ARP entries can be short or long.

A resolved short static ARP entry becomes unresolved upon certain events, for example, when the resolved output interface goes down, or the corresponding VLAN or VLAN interface is deleted.

Long static ARP entries are effective or ineffective. Ineffective long static ARP entries cannot be used for packet forwarding. A long static ARP entry is ineffective when any of the following conditions exists:

·     The IP address in the entry conflicts with a local IP address.

·     No local interface has an IP address in the same subnet as the IP address in the ARP entry.

If you specify the vlan-id interface-type interface-number argument, follow these restrictions and guidelines:

·     The interface can be an Ethernet interface or an aggregate interface.

·     The VLAN and VLAN interface must already exist. The specified Ethernet interface must belong to the specified VLAN.

·     The IP address of the VLAN interface and the IP address specified by the ip-address argument must be on the same network.

·     If a VLAN or VLAN interface is deleted, a long static ARP entry for the VLAN is deleted and a resolved short static ARP entry for the VLAN becomes unresolved.

Examples

# Configure a long static ARP entry that contains IP address 202.38.10.2, MAC address 00e0-fc01-0000, and output interface GigabitEthernet 1/0/1 in VLAN 10.

<Sysname> system-view

[Sysname] arp static 202.38.10.2 00e0-fc01-0000 10 gigabitethernet 1/0/1

Related commands

display arp

reset arp

arp timer aging

Use arp timer aging to set the aging timer for dynamic ARP entries.

Use undo arp timer aging to restore the default.

Syntax

arp timer aging aging-time

undo arp timer aging

Default

The aging timer for dynamic ARP entries is 20 minutes.

Views

System view

Predefined user roles

network-admin

Parameters

aging-time: Specifies the aging timer in minutes. The value range for this argument is 1 to 1440.

Usage guidelines

Each dynamic ARP entry in the ARP table has a limited lifetime, called an aging timer. The aging timer of a dynamic ARP entry is reset each time the dynamic ARP entry is updated. Dynamic ARP entries that are not updated before their aging timers expire are deleted from the ARP table.

Set the aging timer for dynamic ARP entries as needed. For example, when you configure proxy ARP, set a short aging time so that invalid dynamic ARP entries can be deleted in a timely manner.

Examples

# Set the aging timer for dynamic ARP entries to 10 minutes.

<Sysname> system-view

[Sysname] arp timer aging 10

Related commands

display arp timer aging

display arp

Use display arp to display ARP entries.

Syntax

display arp [ [ all | dynamic | static ] | vlan vlan-id | interface interface-type interface-number ] [ count | verbose ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

all: Displays all ARP entries.

dynamic: Displays dynamic ARP entries.

static: Displays static ARP entries.

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

interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command displays ARP entries for all interfaces.

count: Displays the number of ARP entries.

verbose: Displays detailed information about ARP entries.

Usage guidelines

This command displays information about static, dynamic, and multiport ARP entries, including the IP address, MAC address, VLAN ID, output interface, entry type, and aging timer.

Examples

# Display all ARP entries.

<Sysname> display arp all

  Type: S-Static   D-Dynamic   O-Openflow   R-Rule   M-Multiport  I-Invalid

 IP address      MAC address    VLAN/VSI name Interface/Link ID        Aging Type

1.1.1.1         02e0-f102-0023 1             GE1/0/1                  --    S

1.1.1.2         00e0-fc00-0001 12            GE1/0/2                  16    D

# Display detailed information about all ARP entries.

<Sysname> display arp all verbose

  Type: S-Static   D-Dynamic   O-Openflow   R-Rule   M-Multiport  I-Invalid

IP Address: 1.1.1.1             SVLAN/CVLAN: 1000/1001   Aging: --

MAC Address: 02e0-f102-0023     Type: S                  Nickname: 0x0000

Interface/Link ID: GE1/0/1

VPN Instance: --

VXLAN ID: --

VSI Name: --

VSI Interface: --

MPLS PW ID: --

MPLS peer PE address: --

IP Address: 1.1.1.2             SVLAN/CVLAN: --/--       Aging: --

MAC Address: 0015-e944-adc5     Type: D                  Nickname: 0x0000

Interface/Link ID: GE1/0/2

VPN Instance: --

VXLAN ID: --

VSI Name: --

VSI Interface: --

MPLS PW ID: --

MPLS peer PE address: --

# Display the number of all ARP entries.

<Sysname> display arp all count

 Total number of entries : 3

Table 1 Command output

Field

Description

IP Address

IP address in an ARP entry.

MAC Address

MAC address in an ARP entry.

VLAN/VSI name

ID of the VLAN to which the ARP entry belongs. This field displays hyphens (--) in either of the following situations:

·     The ARP entry is an unresolved short static ARP entry.

·     The output interface of the ARP entry does not belong to the VLAN.

Interface/Link ID

Output interface or link ID in the ARP entry. This field displays hyphens (--) in either of the following situations:

·     The ARP entry is an unresolved short static ARP entry.

·     The ARP entry is a multiport ARP entry and has no output interface information.
To obtain the output interface information of the multiport ARP entry, look up the MAC address table according to the MAC address in the ARP entry.

Aging

Aging time for an ARP entry in minutes.

For a static ARP entry, this field always displays hyphens (--). The static ARP entry never ages out unless you delete it manually.

For a dynamic ARP entry, this field displays hyphens (--) if the aging time is unknown.

Type

ARP entry type:

·     D—Dynamic.

·     S—Static.

·     O—OpenFlow.

·     R—Rule.

·     I—Invalid.

SVLAN/CVLAN

ID of the SVLAN or CVLAN to which the ARP entry belongs. This field displays hyphens (--) in either of the following situations:

·     The ARP entry is an unresolved short static ARP entry.

·     The output interface of the ARP entry does not belong to a SVLAN or CVLAN.

VPN Instance

This field is not supported in the current software version.

Name of VPN instance. If no VPN instance is configured for the ARP entry, this field displays hyphens (--).

VXLAN ID

This field is not supported in the current software version.

ID of the VXLAN to which the ARP entry belongs. VXLAN ID is also called VNI. If the ARP entry does not belong to any VXLAN, this field displays hyphens (--).

VSI Name

This field is not supported in the current software version.

Name of the VSI to which the ARP entry belongs. If the ARP entry does not belong to any VSI, this field displays hyphens (--).

VSI Interface

This field is not supported in the current software version.

Name of the gateway interface of the VSI. If no gateway interface is specified for the VSI, this field displays hyphens (--).

MPLS PW ID

This field is not supported in the current software version.

ID of the PW to which the ARP entry belongs. This field displays two hyphens (--) if the ARP entry does not belong to a PW.

MPLS peer PE address

This field is not supported in the current software version.

IP address of the remote PE on the PW. This field displays two hyphens (--) if the ARP entry does not belong to a PW.

Nickname

This field is not supported in the current software version.

Nickname of the ARP entry. The nickname is a string of four hexadecimal numbers, for example, 0x012a.

Total number of entries

Number of ARP entries.

 

Related commands

arp static

reset arp

display arp ip-address

Use display arp ip-address to display the ARP entry for an IP address.

Syntax

display arp ip-address [ verbose ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

ip-address: Displays the ARP entry for the specified IP address.

verbose: Displays the detailed information about the specified ARP entry.

Usage guidelines

The ARP entry information includes the IP address, MAC address, VLAN ID, output interface, entry type, and aging timer.

Examples

# Display the ARP entry for the IP address 20.1.1.1.

<Sysname> display arp 20.1.1.1

  Type: S-Static   D-Dynamic   O-Openflow   R-Rule  I-Invalid

IP address      MAC address    VLAN/VSI name Interface/Link ID        Aging Type

20.1.1.1        00e0-fc00-0001 --            --                       --    S

Related commands

arp static

reset arp

display arp timer aging

Use display arp timer aging to display the aging timer of dynamic ARP entries.

Syntax

display arp timer aging

Views

Any view

Predefined user roles

network-admin

network-operator

Examples

# Display the aging timer of dynamic ARP entries.

<Sysname> display arp timer aging

Current ARP aging time is 20 minute(s)(default)

Related commands

arp timer aging

reset arp

Use reset arp to clear ARP entries from the ARP table.

Syntax

reset arp { all | dynamic | interface interface-type interface-number | static }

Views

User view

Predefined user roles

network-admin

Parameters

all: Clears all ARP entries.

dynamic: Clears all dynamic ARP entries.

static: Clears all static ARP entries.

interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command clears ARP entries for all interfaces.

Examples

# Clear all static ARP entries.

<Sysname> reset arp static

Related commands

arp static

display arp


Gratuitous ARP commands

arp ip-conflict log prompt

Use arp ip-conflict log prompt to enable IP conflict notification.

Use undo arp ip-conflict log prompt to restore the default.

Syntax

arp ip-conflict log prompt

undo arp ip-conflict log prompt

Default

IP conflict notification is disabled.

Views

System view

Predefined user roles

network-admin

Examples

# Enable IP conflict notification on the device.

<Sysname> system-view

[Sysname] arp ip-conflict log prompt

arp send-gratuitous-arp

Use arp send-gratuitous-arp to enable periodic sending of gratuitous ARP packets on an interface.

Use undo arp send-gratuitous-arp to disable the interface from periodically sending gratuitous ARP packets.

Syntax

arp send-gratuitous-arp [ interval interval ]

undo arp send-gratuitous-arp

Default

Periodic sending of gratuitous ARP packets is disabled.

Views

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Parameters

interval interval: Specifies the sending interval in the range of 200 to 200000 milliseconds. The default value is 2000 milliseconds.

Usage guidelines

This feature takes effect on an interface only when the interface has an IP address and the data link layer state of the interface is up.

This feature can send gratuitous ARP requests only for a VRRP virtual IP address, or the sending interface's primary IP address or manually configured secondary IP address. The primary IP address can be configured manually or automatically, whereas the secondary IP address must be configured manually.

If you change the sending interval for gratuitous ARP packets, the configuration takes effect at the next sending interval.

The sending interval for gratuitous ARP packets might be much longer than the set interval when any of the following conditions exist:

·     This feature is enabled on multiple interfaces.

·     Each interface is configured with multiple secondary IP addresses.

·     A small sending interval is configured in the preceding cases.

Examples

# Enable VLAN-interface 2 to send gratuitous ARP packets every 300 milliseconds.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] arp send-gratuitous-arp interval 300

gratuitous-arp mac-change retransmit

Use gratuitous-arp mac-change retransmit to set the times and the interval for retransmitting a gratuitous ARP packet for the device MAC address change.

Use undo gratuitous-arp mac-change retransmit to restore the default.

Syntax

gratuitous-arp mac-change retransmit times interval seconds

undo gratuitous-arp mac-change retransmit

Default

The device sends a gratuitous packet for its MAC address change once only.

Views

System view

Predefined user roles

network-admin

Parameters

times: Specifies the times of retransmitting a gratuitous packet, in the range of 1 to 10.

interval seconds: Specifies the interval for retransmitting a gratuitous packet, in the range of 1 to 10 seconds.

Usage guidelines

The device sends a gratuitous ARP packet to inform other devices of its MAC address change. However, the other devices might fail to receive the packet because the device sends the gratuitous ARP packet once only by default. Use this command to configure gratuitous ARP retransmission parameters to ensure that the other devices can receive the packet.

After you execute this command, the device will retransmit a gratuitous ARP packet for its MAC address change at the specified interval for the specified times.

Examples

# Set the times to 3 and the interval to 5 for retransmitting a gratuitous ARP packet for the device MAC address change.

<Sysname> system-view

[Sysname] gratuitous-arp mac-change retransmit 3 interval 5

gratuitous-arp-learning enable

Use gratuitous-arp-learning enable to enable learning of gratuitous ARP packets.

Use undo gratuitous-arp-learning enable to disable learning of gratuitous ARP packets.

Syntax

gratuitous-arp-learning enable

undo gratuitous-arp-learning enable

Default

Learning of gratuitous ARP packets is enabled.

Views

System view

Predefined user roles

network-admin

Usage guidelines

The learning of gratuitous ARP packets feature allows a device to maintain its ARP table by creating or updating ARP entries based on received gratuitous ARP packets.

When this feature is disabled, the device uses received gratuitous ARP packets to update existing ARP entries only. ARP entries are not created based on the received gratuitous ARP packets, which saves ARP table space.

Examples

# Enable learning of gratuitous ARP packets.

<Sysname> system-view

[Sysname] gratuitous-arp-learning enable

gratuitous-arp-sending enable

Use gratuitous-arp-sending enable to enable sending gratuitous ARP packets upon receiving ARP requests whose sender IP address is on a different subnet.

Use undo gratuitous-arp-sending enable to disable sending gratuitous ARP packets upon receiving ARP requests whose sender IP address is on a different subnet.

Syntax

gratuitous-arp-sending enable

undo gratuitous-arp-sending enable

Default

A device does not send gratuitous ARP packets when it receives ARP requests whose sender IP address is on a different subnet.

Views

System view

Predefined user roles

network-admin

Examples

# Disable a device from sending gratuitous ARP packets upon receiving ARP requests whose sender IP address is on a different subnet.

<Sysname> system-view

[Sysname] undo gratuitous-arp-sending enable


Proxy ARP commands

display local-proxy-arp

Use display local-proxy-arp to display the local proxy ARP status.

Syntax

display local-proxy-arp [ 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, this command displays the local proxy ARP status for all interfaces.

Usage guidelines

You can use this command to check whether local proxy ARP is enabled or disabled.

Examples

# Display the local proxy ARP status for VLAN-interface 2.

<Sysname> display local-proxy-arp interface vlan-interface 2

Interface Vlan-interface2

 Local Proxy ARP status: enabled

Related commands

local-proxy-arp enable

display proxy-arp

Use display proxy-arp to display the proxy ARP status.

Syntax

display proxy-arp [ 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, this command displays the proxy ARP status for all interfaces.

Usage guidelines

You can use this command to check whether proxy ARP is enabled or disabled.

Examples

# Display the proxy ARP status on VLAN-interface 2.

<Sysname> display proxy-arp interface vlan-interface 2

Interface Vlan-interface2

 Proxy ARP status: disabled

Related commands

proxy-arp enable

local-proxy-arp enable

Use local-proxy-arp enable to enable local proxy ARP.

Use undo local-proxy-arp enable to disable local proxy ARP.

Syntax

local-proxy-arp enable [ ip-range start-ip-address to end-ip-address ]

undo local-proxy-arp enable

Default

Local proxy ARP is disabled.

Views

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Parameters

ip-range start-ip-address to end-ip-address: Specifies the IP address range for which local proxy ARP is enabled. The start IP address must be lower than or equal to the end IP address.

Usage guidelines

Proxy ARP enables a device on a network to answer ARP requests for an IP address not on that network. With proxy ARP, hosts in different broadcast domains can communicate with each other as they do on the same network.

Proxy ARP includes common proxy ARP and local proxy ARP.

Common proxy ARP allows communication between hosts that connect to different Layer 3 interfaces and reside in different broadcast domains.

Local proxy ARP allows communication between hosts that connect to the same Layer 3 interface and reside in different broadcast domains.

If you execute this command multiple times, the most recent configuration takes effect.

Examples

# Enable local proxy ARP on VLAN-interface 2.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] local-proxy-arp enable

# Enable local proxy ARP on VLAN-interface 2 for an IP address range.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] local-proxy-arp enable ip-range 1.1.1.1 to 1.1.1.20

Related commands

display local-proxy-arp

proxy-arp enable

Use proxy-arp enable to enable proxy ARP.

Use undo proxy-arp enable to disable proxy ARP.

Syntax

proxy-arp enable

undo proxy-arp enable

Default

Proxy ARP is disabled.

Views

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Usage guidelines

Proxy ARP enables a device on a network to answer ARP requests for an IP address not on that network. With proxy ARP, hosts in different broadcast domains can communicate with each other as they do on the same network.

Proxy ARP includes common proxy ARP and local proxy ARP.

Common proxy ARP allows communication between hosts that connect to different Layer 3 interfaces and reside in different broadcast domains.

Local proxy ARP allows communication between hosts that connect to the same Layer 3 interface and reside in different broadcast domains.

Examples

# Enable proxy ARP on VLAN-interface 2.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] proxy-arp enable

Related commands

display proxy-arp

 

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