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arp (Interfaces)

 

Syntax

Syntax (EX Series)

Hierarchy Level

Note

The edit logical-systems hierarchy is not available on QFabric systems.

Release Information

Statement introduced before Junos OS Release 7.4.

Statement introduced in Junos OS Release 9.0 for EX Series switches.

Statement introduced in Junos OS Release 11.1 for the QFX Series.

Statement introduced in Junos OS Release 14.1X53-D20 for the OCX Series.

Description

For Ethernet, Fast Ethernet, and Gigabit Ethernet interfaces only, configure Address Resolution Protocol (ARP) table entries, mapping IP addresses to MAC addresses. You can enable backup VRRP routers to learn ARP requests for VRRP-IP to VRRP-MAC address translation. You can also set the time interval between ARP updates.

Note

By default, an ARP policer is installed that is shared among all the Ethernet interfaces on which you have configured the family inet statement. By including the arp statement at the [edit interfaces interface-name unit logical-unit-number family inet policer] hierarchy level, you can apply a specific ARP-packet policer to an interface. This feature is not available on EX Series switches.

When you need to conserve IP addresses, you can configure an Ethernet interface to be unnumbered by including the unnumbered-address statement at the [edit interfaces interface-name unit logical-unit-number family inet] hierarchy level.

Note

For EX-Series switches, set only the time interval between ARP updates.

Options

ip-addressIP address to map to the MAC address. The IP address specified must be part of the subnet defined in the enclosing address statement.
mac mac-addressMAC address to map to the IP address. Specify the MAC address as six hexadecimal bytes in one of the following formats: nnnn.nnnn.nnnn or nn:nn:nn:nn:nn:nn. For example, 0000.5e00.5355 or 00:00:5e:00:53:55.
multicast-mac mac-addressMulticast MAC address to map to the IP address. Specify the multicast MAC address as six hexadecimal bytes in one of the following formats: nnnn.nnnn.nnnn or nn:nn:nn:nn:nn:nn. For example, 0000.5e00.5355 or 00:00:5e:00:53:55.
publish(Optional) Have the router or switch reply to ARP requests for the specified IP address. If you omit this option, the router or switch uses the entry to reach the destination but does not reply to ARP requests.
Note

For unicast MAC addresses only, if you include the publish option, the router or switch replies to proxy ARP requests.

aging-timerTime interval in minutes between ARP updates. In environments where the number of ARP entries to update is high (for example, on routers only, metro Ethernet environments), increasing the time between updates can improve system performance.
gratuitous-arp-delay(T Series only) Configure a delay for gratuitous ARP requests at the system level. By default, Junos OS sends gratuitous ARP requests immediately after network-related configuration changes are made on an interface (for example, a VLAN ID, MAC address, or IP address change). This might lead to the Packet Forwarding Engine dropping some initial request packets if the configuration updates have not been fully processed. To avoid such request packets being dropped, you can configure a delay in gratuitous ARP requests.

Values:

  • seconds—Configure the ARP request delay in seconds. We recommend configuring a value in the range of 3 through 6 seconds.

gratuitous-arp-on-ifup(ACX Series, SRX Series, T Series only) Add this statement to the [edit system arp] hierarchy to configure Junos OS to automatically issue a gratuitous ARP announcement when an interface is online.
interfaces(T Series only) Specify the ARP aging timer in minutes for a logical interface of family type inet.

Values: aging-timer minutes—Time between ARP updates, in minutes.

Default: 20

Range: 1 through 6,00,000

passive-learning(M Series, MX Series, PTX Series, SRX Series, T Series only) Configure backup VRRP routers or switches to learn the ARP mappings (IP-to-MAC address) for hosts sending the requests. By default, the backup VRRP router drops these requests; therefore, if the master router fails, the backup router must learn all entries present in the ARP cache of the master router. Configuring passive learning reduces transition delay when the backup router is activated. Learning of ARP mappings (IP-to-MAC address) by backup VRRP routers or switches for hosts sending the requests is disabled unless this statement is configured.
purging(M Series, MX Series, PTX Series, SRX Series, T Series only) Purge obsolete ARP entries from the cache when an interface or link goes offline.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

system—To view this statement in the configuration.

system-control—To add this statement to the configuration.