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show arp

Syntax

Description

Display all entries in the Address Resolution Protocol (ARP) table. To display entries for a particular logical system only, first enter the set cli logical-system logical-system-name command, and then enter the show arp command.

Note:

Starting with Junos OS Release 14.2, the following enhancements have been made to the output of the show arp interfaces command:

  • For integrated routing and bridging (IRB) interfaces, in the output of the show arp command, the IRB interface name is displayed under the Interface field of the output and the Layer 2 interface identifier is specified in square brackets following the IRB name. Until Release 14.1 and earlier, only the layer 2 interface name and not the IRB name was displayed.

  • Starting with release 14.2, if you do not specify a subinterface or a logical unit of the interface with the show arp interface interface-name command, an error message is shown. Until Release 14.1 and earlier, if you did not specify the subinterface for a physical interface, the system considered the supplied command to be for subinterface 0 and displayed the output. For example, if you entered ge-2/2/5, it was processed by the system as ge-2/2/5.0.

  • When IRB interfaces are configured and if you attempt to specify an interface name that is not configured on the system, an error message is displayed stating the particular interface is not defined on the system. Until release 14.1 and earlier, unrelated and incorrect entries were displayed even for interface names that did not exist.

  • Starting with Release 14.2, you can enter the show arp interface command with the IRB name and retrieve the statistical details for the IRB interface. This functionality was not available previously. However, you could previously obtain the ARP details of an IRB interface that had a Layer 2 interface configured.

Note:

Starting with Junos OS Release 16.1, show arp no-resolve command does not display the underlying ifl information if enhanced-convergence statement at [edit irb unit unit-number hierarchy level and enhanced-ip statement at [edit chassis network-services] hierarchy level is configured for the destination interface IRB.

Options

none

Display the entries in the ARP table.

expiration-time

(Optional) Display the amount of time, in seconds, until each ARP entry is set to expire.

hostname host-name

(Optional) Display the hostname.

interface interface-name

(Optional) Display information about ARP for the specified logical interface

logical-system logical-system-name

(Optional) Display ARP entries for the specified logical system; only available on the main router context.

no-resolve

(Optional) Do not attempt to determine the hostname that corresponds to the IP address.

reference-count count

(Optional) Display the next-hop reference count.

state state

(Optional) Display the next-hop current state.

tenant name

(Optional) Display the ARP entries for the specified tenant. Only available in the main router context.

vpn vpn-name

(Optional) Display entries in the ARP table for the specified virtual private network’s (VPN) routing table.

Note:
  • The vpn option displays only entries for non-subscriber interfaces. You must omit this option if you want to view ARP entries for subscriber interfaces.

  • The show arp vpn vpn-name no-resolve command does not display entries for subscriber interfaces in the non-default routing-instance, that is when the subscriber interface is coming up in the non-default routing-instance.

Required Privilege Level

view

Output Fields

Table 1 describes the output fields for the show arp command. Output fields are listed in the approximate order in which they appear.

Table 1: show arp Output Fields

Field Name

Field Description

MAC Address

Media access control (MAC) address that corresponds to the IP address.

Address

IP address that corresponds to the hostname.

Name

Hostname.

Interface

Interface name.

Flags

(no-resolve option only) Indicates how mappings between IP and MAC addresses are defined:

  • Permanent—Static mapping.

  • Permanent and published—Static mapping that is published.

  • None—Dynamic mapping.

TTE

(expiration-time option only) Amount of time, in seconds, until ARP entry is set to expire.

Sample Output

show arp

show arp no-resolve

show arp no-resolve

The command is displaying the MAC and MAC-IP routes are programmed over the .local interface.

command-name

The command displaying the underlying l2 ifl information when enhanced-convergence statement and enhanced-ip statement is not configured.

The command not displaying the underlying l2 ifl information when enhanced-convergence statement and enhanced-ip statement is configured.

show arp expiration-time

Release Information

Command introduced before Junos OS Release 7.4.

expiration-time option added in Junos OS Release 8.1.

logical-system and vpn options added in Junos OS Release 10.1.

reference-count, tenant, and state options added in Junos OS Release 18.3.