arp (Interfaces)
Syntax
arp ip-address (mac | multicast-mac) mac-address publish;
arp {
aging-timer minutes;
gratuitous-arp-delayseconds;
gratuitous-arp-on-ifup;
interfaces {
interface-name {
aging-timer minutes;
}
}
passive-learning;
purging;
}
Syntax (EX Series)
arp {
aging-timer minutes;
}
Hierarchy Level
[edit interfaces interface-name unit logical-unit-number family inet address address]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number family inet address address]
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.
NoteBy 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.
NoteFor EX-Series switches, set only the time interval between
ARP updates.
Options
ip-address—IP 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-address—MAC 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-address—Multicast 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.
NoteFor unicast MAC addresses only, if you include the publish option, the router or switch replies to proxy ARP requests.
aging-timer—Time 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.
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.
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.
