Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 

show interfaces (Loopback)

 

Syntax

Release Information

Command introduced before Junos OS Release 7.4.

Description

Display status information about the local loopback interface.

Note

Logical interface lo0.16385 is the loopback interface for the internal routing instance. Created by the internal routing service process, this interface facilitates internal traffic. It prevents any filter created on loopback lo0.0 from blocking internal traffic.

Options

lo0Display standard status information about the local loopback interface.
brief | detail | extensive | terse(Optional) Display the specified level of output.
descriptions(Optional) Display interface description strings.
media(Optional) Display media-specific information.
snmp-index snmp-index(Optional) Display information for the specified SNMP index of the interface.
statistics(Optional) Display static interface statistics.

Required Privilege Level

view

List of Sample Output

show interfaces (Loopback)

show interfaces brief (Loopback)

show interfaces detail (Loopback)

show interfaces extensive (Loopback)

Output Fields

Table 1 lists the output fields for the show interfaces (loopback) command. Output fields are listed in the approximate order in which they appear.

Table 1: Loopback show interfaces Output Fields

Field Name

Field Description

Level of Output

Physical Interface 

Physical Interface

Name of the physical interface.

All levels

Enabled

State of the interface. Possible values are described in the “Enabled Field” section under Common Output Fields Description.

All levels

Interface index

Physical interface index number, which reflects its initialization sequence.

detail extensive none

SNMP ifIndex

SNMP index number for the physical interface.

detail extensive none

Generation

Unique number for use by Juniper Networks technical support only.

detail extensive

Type

Type of interface.

All levels

Link-level type

Encapsulation type used on the physical interface.

All levels

MTU

Size of the largest packet to be transmitted.

All levels

Clocking

Reference clock source of the interface.

All levels

Speed

Network speed on the interface.

All levels

Device flags

Information about the physical device. Possible values are described in the “Device Flags” section under Common Output Fields Description.

All levels

Interface flags

Information about the interface. Possible values are described in the “Interface Flags” section under Common Output Fields Description.

All levels

Link type

Data transmission type.

detail extensive

Link flags

Information about the link. Possible values are described in the “Link Flags” section under Common Output Fields Description.

detail extensive none

Physical info

Information about the physical interface.

detail extensive

Hold-times

Current interface hold-time up and hold-time down. Value is in milliseconds.

detail extensive

Current address

Configured MAC address.

detail extensive

Hardware address

Media access control (MAC) address of the interface.

detail extensive

Alternate link address

Backup link address.

detail extensive

Last flapped

Date, time, and how long ago the interface went from down to up. The format is Last flapped: year-month-day hour:minute:second timezone (hour:minute:second ago). For example, Last flapped: 2002-04-26 10:52:40 PDT (04:33:20 ago).

detail extensive

Statistics last cleared

Time when the statistics for the interface were last set to zero.

detail extensive

Traffic statistics

Number and rate of bytes and packets received and transmitted on the physical interface.

  • Input bytes, Output bytes—Number of bytes received and transmitted on the interface.

  • Input packets, Output packets—Number of packets received and transmitted on the interface.

detail extensive

Input errors

  • Errors—Input errors on the interface.

  • Drops—Number of packets dropped by the output queue of the I/O Manager ASIC.

  • Framing errors—Number of packets received with an invalid frame checksum (FCS).

  • Runts—Frames received smaller than the runt threshold.

  • Giants—Frames received larger than the giant threshold.

  • Policed Discards—Frames that the incoming packet match code discarded because the frames were not recognized or were not of interest. Usually, this field reports protocols that Junos does not support.

  • Resource errors—Sum of transmit drops.

extensive

Output errors

  • Carrier transitions—Number of times the interface has gone from down to up. This number does not normally increment quickly, increasing only when the cable is unplugged, the far-end system is powered down and then up, or another problem occurs. If the number of carrier transitions increments quickly, possibly once every 10 seconds, the cable, the remote system, or the interface is malfunctioning.

  • Errors—Sum of outgoing frame aborts and FCS errors.

  • Drops—Number of packets dropped by the output queue of the I/O Manager ASIC. If the interface is saturated, this number increments once for every packet dropped by the ASIC RED mechanism.

  • MTU errors—Number of packets larger than the MTU threshold.

  • Resource errors—Sum of transmit drops.

extensive

Logical Interface 

Logical interface

Name of the logical interface.

All levels

Index

Logical interface index number, which reflects its initialization sequence.

detail extensive

SNMP ifIndex

Logical interface SNMP interface index number.

detail extensive

Generation

Unique number for use by Juniper Networks technical support only.

detail extensive

Flags

Information about the logical interface; values are described in the “Logical Interface Flags” section under Common Output Fields Description.

brief detail extensive

Encapsulation

Encapsulation on the logical interface.

brief detail extensive

Input packets

Number of packets received on the logical interface.

None specified

Output packets

Number of packets transmitted on the logical interface.

None specified

Traffic statistics

Total number of bytes and packets received and transmitted on the logical interface. These statistics are the sum of the local and transit statistics. When a burst of traffic is received, the value in the output packet rate field might briefly exceed the peak cell rate. It takes awhile (generally, less than 1 second) for this counter to stabilize.

detail extensive

Local statistics

Statistics for traffic received from and transmitted to the Routing Engine. When a burst of traffic is received, the value in the output packet rate field might briefly exceed the peak cell rate. It takes awhile (generally, less than 1 second) for this counter to stabilize.

detail extensive

Protocol

Protocol family configured on the logical interface (such as iso or inet6).

detail extensive none

MTU

MTU size on the logical interface.

detail extensive none

Generation

Unique number for use by Juniper Networks technical support only.

detail extensive

Route Table

Route table in which this address exists; for example, Route table:0 refers to inet.0.

detail extensive

Flags

Information about the protocol family flags. Possible values are described in the “Family Flags” section under Common Output Fields Description.

detail extensive none

Addresses, Flags

Information about the address flags. Possible values are described in the “Addresses Flags” section under Common Output Fields Description.

detail extensive

Destination

IP address of the remote side of the connection.

detail extensive none

Local

IP address of the logical interface.

detail extensive none

Broadcast

Broadcast address on the logical interface.

detail extensive none

Generation

Unique number for use by Juniper Networks technical support only.

detail extensive

Sample Output

show interfaces (Loopback)

user@host> show interfaces lo0

show interfaces brief (Loopback)

user@host> show interfaces lo0 brief

show interfaces detail (Loopback)

user@host> show interfaces lo0 detail

show interfaces extensive (Loopback)

user@host> show interfaces lo0 extensive