The default command might interrupt ongoing network services. Make sure you are fully aware of the impacts of this command when you perform it on a live network.

Use default to restore the default settings for the loopback or null interface.

This command might fail to restore the default settings for some commands for reasons such as command dependencies and system restrictions. Use the display this command in interface view to identify these commands, and then use their undo forms or follow the command reference to individually restore their default settings. If your restoration attempt still fails, follow the error message instructions to resolve the problem.

Examples

# Restore the default settings for interface loopback 1.

<Sysname> system-view

[Sysname] interface Loopback 1

[Sysname-Loopback1] default

This command will restore the default settings. Continue? [Y/N]:y

description

Syntax

description text

undo description

View

Loopback interface view, Null 0 interface view

Default level

2: System level

Parameters

text: Specifies an interface description, a string of 1 to 80 characters, which supports spaces, characters and symbols found in standard English (such as numbers and case-sensitive letters), special English, and other characters or symbols that conform to the Unicode standard.

NOTE:

· An interface description can be a mixture of English characters and other Unicode characters. The mixed description cannot exceed the specified length.

· To use a type of Unicode characters or symbols in an interface description, install the specific input method editor and log in to the switch through supported remote login software.

· When the length of a description string reaches or exceeds the maximum line width on the terminal software, the software starts a new line, possibly breaking a Unicode character into two. As a result, garbled characters might be displayed at the end of a line.

· Each non-English Unicode character or symbol (non-English characters) takes the space of two regular characters. When the length of a description string reaches or exceeds the maximum line width on the terminal software, the software starts a new line. This might break a Unicode character into two parts and create garbled characters at the end of a line.

Description

Use description to configure a description for the current interface.

Use undo description to restore the default.

By default, the description of a loopback or null interface is interface name Interface, for example, LoopBack2 Interface.

Related commands: display interface.

Examples

# Set the description of interface LoopBack2 to PIM-SM RP.

[Sysname] interface Loopback 2

[Sysname-LoopBack2] description PIM-SM RP

display interface loopback

Syntax

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

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

View

Any view

Default level

1: Monitor level

Parameters

interface-number: Specifies a loopback interface by its number, which can be the number of any existing loopback interface.

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 25 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 the information about a loopback interface.

If you do not specify the loopback keyword, this command displays information about all interfaces on the device.

If you specify the loopback keyword without the interface-number argument, this command displays information about all created loopback interfaces.

Related commands: interface loopback.

Examples

# View the 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 Address is 2.2.2.2/32 Primary

Physical is Loopback

Last clearing of counters: Never

Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

Last 300 seconds output rate: 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) --

# Display brief information about all loopback interfaces in DOWN state.

<Sysname> display interface Loopback brief down

The brief information of interface(s) under route mode:

Link: ADM - administratively down; Stby - standby

Interface Link Cause

Loop1 ADM Administratively

Table 1 Command output

Field	Description
current state	Physical state (up or 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. That is, when the network layer protocol state of the interface is displayed as up, the corresponding link might 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. This field appears when no IP address is configured for the interface.
Internet Address is 2.2.2.2/32 Primary	Primary IP address of the interface. This field does not appear if no primary IP address is configured for the interface.
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 with the reset counters interface command since the switch starts, Never is displayed for this field.
Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec	Input rate during the latest 300 seconds, which is measured in bytes per second, bits per second, and packets per second.
Last 300 seconds output rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec	Output rate during the latest 300 seconds, which is measured in bytes per second, bits per second, and packets 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 the 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 the 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, perform 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: · UP. · DOWN. · UP(s).
Main IP	Main IP address of the interface.
Description	Description of the interface.
Cause	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.

display interface null

Syntax

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

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

View

Any view

Default level

1: Monitor level

Parameters

0: Specifies interface Null 0. The interface number is fixed at 0, because the switch has only one null interface.