display interface loopback

Syntax

display interface [ loopback ] [ brief [ down | description ] ] [ | { begin | exclude | include } regular-expression ]

display interface loopback 0 [ brief [ description ] ] [ | { begin | exclude | include } regular-expression ]

View

Any view

Default level

1: Monitor level

Parameters

0: Loopback interface number, which is fixed at 0.

brief: Displays brief interface information. If you do not specify this keyword, this command displays detailed interface information.

down: Displays information about interfaces in down state and the causes. If you do not specify this keyword, this command displays information about interfaces in all states.

description: Displays complete interface descriptions. If you do not specify this keyword, the command displays only the first 27 characters of interface descriptions.

|: Filters command output by specifying a regular expression. For more information about regular expressions, see Fundamentals Configuration Guide.

begin: Displays the first line that matches the specified regular expression and all lines that follow.

exclude: Displays all lines that do not match the specified regular expression.

include: Displays all lines that match the specified regular expression.

regular-expression: Specifies a regular expression, a case-sensitive string of 1 to 256 characters.

Description

Use display interface loopback to display information about a loopback interface.

If you do not specify the loopback keyword, this command displays information about all interfaces on the device.
The device supports only one loopback interface, loopback 0, and therefore this command displays information about loopback 0 whether you specify loopback or loopback 0.

Related commands: interface loopback.

Examples

# Display detailed information about interface loopback 0.

<Sysname> display interface loopback 0
LoopBack0 current state: UP
Line protocol current state: UP (spoofing)
Description: LoopBack0 Interface
The Maximum Transmit Unit is 1536
Internet protocol processing : disabled
Physical is Loopback
Port priority: 0
Last clearing of counters:  Never
    Last 300 seconds input:  0 bytes/sec, 0 bits/sec, 0 packets/sec
    Last 300 seconds output:  0 bytes/sec, 0 bits/sec, 0 packets/sec
    0 packets input, 0 bytes, 0 drops
    0 packets output, 0 bytes, 0 drops

# Display brief information about interface loopback 0.

<Sysname> display interface loopback 0 brief
The brief information of interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface            Link Protocol Main IP         Description
Loop0                UP   UP(s)    --

Table 10: Command output

Field	Description
current state	Physical state (up or administratively down) of the interface.
Line protocol current state	State of the data link layer protocol: up (spoofing). Spoofing refers to the spoofing attribute of the interface. When the network layer protocol state of the interface is displayed as up, the corresponding link may not exist, or the corresponding link is non-permanent and established on demand.
Description	Description string of the interface.
The Maximum Transmit Unit	Maximum transmission unit (MTU) of the interface.
Internet protocol processing	State (enabled or disabled) of the network layer protocol (displayed as Internet Address is X.X.X.X/XX Primary).
Physical is loopback	The physical type of the interface is loopback.
Last clearing of counters	Time when statistics on the logical interface were last cleared by using the reset counters interface command. If the statistics of the interface have never been cleared by using the reset counters interface command since device startup, this field displays Never.
Last 300 seconds input: 0 bytes/sec, 0 bits/sec, 0 packets/sec	Average input rate during the last 300 seconds (displayed when the interface supports traffic accounting), where the following conditions apply: packets/sec indicates the average number of packets received per second. bytes/sec indicates the average number of bytes received per second. bits/sec indicates the average number of bits received per second.
Last 300 seconds output: 0 bytes/sec, 0 bits/sec, 0 packets/sec	Average output rate over the last 300 seconds (displayed when the interface supports traffic accounting), where the following conditions apply: packets/sec indicates the average number of packets sent per second. bytes/sec indicates the average number of bytes sent per second. bits/sec indicates the average number of bits sent per second.
0 packets input, 0 bytes, 0 drops	Total number and size (in bytes) of input packets of the interface and the number of dropped packets.
0 packets output, 0 bytes, 0 drops	Total number and size (in bytes) of output packets of the interface and the number of dropped packets.
The brief information of interface(s) under route mode	Brief information about Layer 3 interfaces.
Link: ADM - administratively down; Stby - standby	Link status: ADM—The interface has been administratively shut down. To recover its physical state, execute the undo shutdown command. Stby—The interface is operating as a backup interface.
Protocol: (s) - spoofing	If the network layer protocol state of an interface is shown as UP, but its link is an on-demand link or not present at all, its protocol attribute includes the spoofing flag (an s in parentheses).
Interface	Abbreviated interface name.
Link	Physical link state of the interface: UP—The link is up. ADM—The link has been administratively shut down. To recover its physical state, perform the undo shutdown command.
Protocol	Protocol connection state of the interface, which can be UP, DOWN, or UP(s).
Main IP	The main IP address of the interface.
Description	Description of the interface.
Cause	The cause of a DOWN physical link. If the port has been shut down with the shutdown command, this field displays Administratively. To restore the physical state of the interface, use the undo shutdown command.

NOTE:

The switch does not support collecting statistics about average input or output rate of loopback interfaces. These fields display 0.

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