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| Title | Size | Download |
|---|---|---|
| 03-Loopback, null, and inloopback interface commands | 135.56 KB |
bandwidth
Use bandwidth to configure the expected bandwidth of an interface.
Use undo bandwidth to restore the default.
Syntax
bandwidth bandwidth-value
undo bandwidth
Default
The expected bandwidth of a loopback interface is 0 kbps.
Views
Loopback interface view
Predefined user roles
network-admin
mdc-admin
Parameters
bandwidth-value: Specifies the expected bandwidth in the range of 1 to 400000000 kbps.
Usage guidelines
The expected bandwidth of an interface affects the following items:
· Bandwidth assignment with CBQ. For more information, see ACL and QoS Configuration Guide.
· Link costs in OSPF, OSPFv3, and IS-IS. For more information, see Layer 3—IP Routing Configuration Guide.
Examples
# Set the expected bandwidth of Loopback 1 to 1000 kbps.
<Sysname> system-view
[Sysname] interface loopback 1
[Sysname-LoopBack1] bandwidth 1000
default
Use default to restore the default settings for a loopback or null interface.
Syntax
default
Views
Loopback interface view, null interface view
Predefined user roles
network-admin
mdc-admin
Usage guidelines
|
|
CAUTION: The default command might interrupt ongoing network services. Make sure you are fully aware of the impacts of this command before using it on a live network. |
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 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
description
Use description to set a description for an interface.
Use undo description to restore the default.
Syntax
description text
undo description
Default
The description of a loopback or null interface is the interface name plus Interface (for example, LoopBack1 Interface).
Views
Loopback interface view, null interface view
Predefined user roles
network-admin
mdc-admin
Parameters
text: Specifies an interface description, a string of 1 to 255 characters.
Usage guidelines
Configure a description for an interface for easy identification and management purposes.
You can use the display interface command to view the configured description.
Examples
# Set the description to for RouterID for interface loopback 1.
<Sysname> system-view
[Sysname] interface loopback 1
[Sysname-LoopBack1] description for RouterID
display interface inloopback
Use display interface inloopback to display information about the inloopback interface.
Syntax
display interface [ inloopback [ 0 ] ] [ brief [ description ] ]
Views
Any view
Predefined user roles
network-admin
network-operator
mdc-admin
mdc-operator
Parameters
0: Specifies interface Inloopback 0.
brief: Displays brief interface information. If you do not specify this keyword, the command displays detailed interface information.
description: Displays complete interface descriptions. If you do not specify this keyword, the command displays only the first 27 characters of interface descriptions. The description of an inloopback interface is always InLoopBack0 Interface and cannot be configured.
Usage guidelines
If the inloopback keyword is not specified, the command displays information about all interfaces of the device.
If the inloopback keyword is specified but the 0 keyword is not specified, the command displays information about interface Inloopback 0. This is because the device has only one inloopback interface Inloopback 0.
Examples
# Display detailed information about interface Inloopback 0.
<Sysname> display interface inloopback 0
InLoopBack0
Current state: UP
Line protocol state: UP(spoofing)
Description: InLoopBack0 Interface
Bandwidth: 0kbps
Maximum Transmit Unit: 1536
Physical: InLoopBack
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
Input: 0 packets, 0 bytes, 0 drops
Output: 0 packets, 0 bytes, 0 drops
Table 1 Command output
|
Field |
Description |
|
Current state |
Physical layer state of the interface, which is always UP, meaning that the inloopback can receive and transmit packets. |
|
Line protocol state |
Data link layer protocol state of the interface, which is always UP(spoofing). UP(spoofing) means that the data link layer protocol state of the interface is up, but the link is an on-demand link or is not present. |
|
Description |
Description string of the interface, which is always InLoopBack0 Interface and cannot be configured. |
|
Bandwidth |
Expected bandwidth of the interface. |
|
Maximum Transmit Unit |
MTU of the interface, which is always 1536 and cannot be configured |
|
Physical: InLoopBack |
The physical type of the interface is inloopback. |
|
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 statistics collection): · bytes/sec—Average number of bytes received per second. · bits/sec—Average number of bits received per second. · packets/sec—Average number of packets 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 statistics collection): · bytes/sec—Average number of bytes sent per second. · bits/sec—Average number of bits sent per second. · packets/sec—Average number of packets sent per second. |
|
Input: 0 packets, 0 bytes, 0 drops |
Total number and size (in bytes) of incoming packets of the interface and the number of dropped packets (displayed when the interface supports traffic statistics collection). |
|
Output: 0 packets, 0 bytes, 0 drops |
Total number and size (in bytes) of outgoing packets of the interface and the number of dropped packets (displayed when the interface supports traffic statistics collection). |
# Display brief information about interface Inloopback 0.
<Sysname> display interface inloopback 0 brief
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface Link Protocol Main IP Description
InLoop0 UP UP(s) --
# Display brief information about interface Inloopback 0, including the complete description of the inloopback interface.
<Sysname> display interface inloopback 0 brief description
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface Link Protocol Main IP Description
InLoop0 UP UP(s) --
Table 2 Command output
|
Field |
Description |
|
Brief information on interface(s) under route mode: |
Brief information about the inloopback interface. |
|
Link: ADM - administratively down; Stby - standby |
Explains the Link field values: · ADM—The interface has been shut down by the network administrator. To recover its physical layer state, run the undo shutdown command. · Stby—The interface is a standby interface. |
|
Protocol: (s) - spoofing |
Protocol attribute value of the interface. (s) represents spoofing. If the data link layer protocol of an interface is up, but the link is an on-demand link or is not present, the Protocol field displays UP(s). This attribute is typical of interface Null 0, Inloopback 0, and loopback interfaces. |
|
Interface |
Interface name. |
|
Link |
Physical layer state of the interface, which is always UP, meaning that the interface is physically up. |
|
Protocol |
Data link layer protocol state of the interface, which is always UP(s). |
|
Main IP |
IP address of the interface. Because inloopback interfaces do not support CLI configuration, this field does not display a value. |
|
Description |
Interface description configured by using the description command. Because inloopback interfaces do not support CLI configuration, this field does not display a value. |
display interface loopback
Use display interface loopback to display information about the specified or all existing loopback interfaces.
Syntax
display interface [ loopback ] [ brief [ down ] ]
display interface [ loopback [ interface-number ] ] [ brief [ description ] ]
Views
Any view
Predefined user roles
network-admin
network-operator
mdc-admin
mdc-operator
Parameters
interface-number: Specifies a loopback interface by its number, which can be the number of any existing loopback interface. If you do not specify this argument, the command displays information about all existing loopback interfaces on the device.
brief: Displays brief interface information. If you do not specify this keyword, the command displays detailed interface information.
down: Displays information about interfaces in down state and the causes. If you do not specify this keyword, the 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.
Usage guidelines
This command is supported only after a loopback interface is created.
If the loopback keyword is not specified, the command displays information about all interfaces of the device.
If the loopback keyword is specified but the interface-number argument is not specified, the command displays information about all existing loopback interfaces.
Examples
# Display detailed information about interface loopback 0. (Suppose the loopback interface supports traffic statistics collection.)
<Sysname> display interface loopback 0
LoopBack0
Current state: UP
Line protocol state: UP(spoofing)
Description: LoopBack0 Interface
Bandwidth: 0kbps
Maximum Transmit Unit: 1536
Internet protocol processing: disabled
Physical: Loopback
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
Input: 0 packets, 0 bytes, 0 drops
Output: 0 packets, 0 bytes, 0 drops
# Display detailed information about interface loopback 0. (Suppose the loopback interface does not support traffic statistics collection.)
<Sysname> display interface loopback 0
LoopBack0
Current state: UP
Line protocol state: UP(spoofing)
Description: LoopBack0 Interface
Maximum Transmit Unit: 1536
Internet protocol processing : disabled
Physical: Loopback
Last clearing of counters: Never
|
Field |
Description |
|
Current state |
Physical layer state of the loopback interface: · UP—The loopback interface can receive and transmit packets. · Administratively DOWN—The interface was manually shut down by using the shutdown command. |
|
Line protocol state |
Data link layer protocol state of the interface. UP(spoofing) means that the data link layer protocol state of the interface is up, but the link is an on-demand link or is not present. |
|
Description |
Description string of the interface. |
|
Bandwidth |
Expected bandwidth of the interface. |
|
Maximum Transmit Unit |
MTU of the interface. |
|
Internet protocol processing: disabled |
Indicates that the interface cannot process Layer 3 packets (displayed when the interface is not configured with an IP address). |
|
Internet Address is 1.1.1.1/32 Primary |
Primary IP address of the interface (displayed when the interface is configured with a primary IP address). |
|
Physical: 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 the device started, 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 statistics collection): · bytes/sec—Average number of bytes received per second. · bits/sec—Average number of bits received per second. · packets/sec—Average number of packets 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 statistics collection): · bytes/sec—Average number of bytes sent per second. · bits/sec—Average number of bits sent per second. · packets/sec—Average number of packets sent per second. |
|
Input: 0 packets, 0 bytes, 0 drops |
Total number and size (in bytes) of incoming packets of the interface and the number of dropped packets (displayed when the interface supports traffic statistics collection). |
|
Output: 0 packets, 0 bytes, 0 drops |
Total number and size (in bytes) of outgoing packets of the interface and the number of dropped packets (displayed when the interface supports traffic statistics collection). |
# Display brief information about all loopback interfaces.
<Sysname> display interface loopback brief
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface Link Protocol Main IP Description
Loop1 UP UP(s) -- aaaaaaaaaaaaaaaaaaaaaaaaaaa
# Display brief information about all existing loopback interfaces, including the complete description of each loopback interface.
<Sysname> display interface loopback brief description
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface Link Protocol Main IP Description
Loop1 UP UP(s) -- aaaaaaaaaaaaaaaaaaaaaaaaaaaaa
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
# Display information about all loopback interfaces in down state and the causes.
<Sysname> display interface loopback brief down
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Interface Link Cause
Loop1 ADM Administratively
|
Field |
Description |
|
Brief information on interface(s) under route mode: |
Brief information about loopback interfaces. |
|
Link: ADM - administratively down; Stby - standby |
Explains the Link field values: · ADM—The interface has been shut down by the network administrator. To recover its physical layer state, run the undo shutdown command. · Stby—The interface is a standby interface. |
|
Protocol: (s) - spoofing |
Explains the Protocol field value. (s) represents spoofing. If the data link layer protocol of an interface is up, but the link is an on-demand link or is not present, the Protocol field displays UP(s). This attribute is typical of interface Null 0, Inloopback 0, and loopback interfaces. |
|
Interface |
Interface name. |
|
Link |
Physical layer state of the interface: · UP—The interface is up. · DOWN—The interface is physically down. · ADM—The interface has been administratively shut down. To recover its physical state, run the undo shutdown command. · Stby—The interface is a standby interface. |
|
Protocol |
Data link layer protocol state of the interface. |
|
Description |
Interface description configured by using the description command. If the description keyword is not specified in the display interface brief command, the Description field allows a maximum of 27 characters. If the description keyword is specified in the display interface brief command, the field displays the complete interface description. |
|
Cause |
Cause of the interface down event. If the interface has been shut down by using the shutdown command, this field displays Administratively. To restore the physical state of the interface, execute the undo shutdown command. |
Related commands
· interface loopback
· reset counters interface loopback
display interface null
Use display interface null to display information about the null interface.
Syntax
display interface [ null [ 0 ] ] [ brief [ description ] ]
Views
Any view
Predefined user roles
network-admin
network-operator
mdc-admin
mdc-operator
Parameters
0: Specifies interface Null 0.
brief: Displays brief interface information. If you do not specify this keyword, the command displays detailed interface information.
description: Displays complete interface descriptions. If you do not specify this keyword, the command displays only the first 27 characters of interface descriptions.
Usage guidelines
If the null keyword is not specified, the command displays information about all interfaces of the device.
If the null keyword is specified but the 0 keyword is not specified, the command displays information about interface Null 0. This is because the device has only one null interface Null 0.
Examples
# Display detailed information about interface Null 0. (Suppose the null interface supports traffic statistics collection.)
<Sysname> display interface null 0
NULL0
Current state: UP
Line protocol state: UP(spoofing)
Description: NULL0 Interface
Bandwidth: 0kbps
Maximum Transmit Unit: 1500
Internet protocol processing: disabled
Physical: NULL DEV
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
Input: 0 packets, 0 bytes, 0 drops
Output: 0 packets, 0 bytes, 0 drops
# Display detailed information about interface Null 0. (Suppose the null interface does not support traffic statistics collection.)
<Sysname> display interface null 0
NULL0
Current state: UP
Line protocol state: UP(spoofing)
Description: NULL0 Interface
Maximum Transmit Unit: 1500
Internet protocol processing: disabled
Physical: NULL DEV
Last clearing of counters: Never
# Display brief information about interface Null 0.
<Sysname> display interface null 0 brief
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface Link Protocol Main IP Description
NULL0 UP UP(s) -- aaaaaaaaaaaaaaaaaaaaaaaaaaa
# Display brief information about interface Null 0, including the complete description of the null interface.
<Sysname> display interface null 0 brief description
Brief information on interface(s) under route mode:
Link: ADM - administratively down; Stby - standby
Protocol: (s) - spoofing
Interface Link Protocol Main IP Description
NULL0 UP UP(s) -- aaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
For the command output, see Table 3 and Table 4.
Related commands
· interface null
· reset counters interface null
interface loopback
Use interface loopback to create a loopback interface and enter loopback interface view.
Use undo interface loopback to remove a loopback interface.
Syntax
interface loopback interface-number
undo interface loopback interface-number
Default
No loopback interface exists.
Views
System view
Predefined user roles
network-admin
mdc-admin
Parameters
interface-number: Specifies a loopback interface by its number in the range of 0 to 1023.
Usage guidelines
The physical layer state and link layer protocols of a loopback interface are always up unless the loopback interface is manually shut down. You can use a loopback interface to achieve the following purposes:
· Prevent the connection from being affected by the physical state of the interface.
· Improve the reliability of the connection.
For example, you can:
· Configure a loopback interface as the source interface for establishing an FTP connection.
· Use the loopback interface address as the Router ID in BGP.
Examples
# Create interface loopback 1.
<Sysname> system-view
[Sysname] interface loopback 1
interface null
Use interface null to enter null interface view.
Syntax
interface null 0
Default
A device has only one null interface (Null 0), which cannot be created or deleted.
Views
System view
Predefined user roles
network-admin
mdc-admin
Parameters
0: Specifies interface Null 0. The null interface number is always 0.
Examples
# Enter Null 0 interface view.
<Sysname> system-view
[Sysname] interface null 0
reset counters interface loopback
Use reset counters interface loopback to clear the statistics on the specified or all loopback interfaces.
Syntax
reset counters interface loopback [ interface-number ]
Views
User view
Predefined user roles
network-admin
mdc-admin
Parameters
interface-number: Specifies a loopback interface by its number, which can be the number of any existing loopback interface. If you do not specify the interface-number argument, the command clears the statistics on all loopback interfaces.
Usage guidelines
To determine whether a loopback interface works correctly within a period by collecting the traffic statistics within that period, first use the reset counters interface [ loopback [ interface-number ] ] command to clear the statistics. Then have the interface automatically collect the statistics.
This command is available only if at least one loopback interface has been created.
Examples
# Clear the statistics on loopback interface Loopback 1.
<Sysname> reset counters interface loopback 1
Related commands
display interface loopback
reset counters interface null
Use reset counters interface null to clear the statistics on the null interface.
Syntax
reset counters interface [ null [ 0 ] ]
Views
User view
Predefined user roles
network-admin
mdc-admin
Parameters
0: Specifies the number of the null interface, which is always 0.
Usage guidelines
To determine whether the null interface works correctly within a period by collecting the traffic statistics within that period, first use the reset counters interface [ null [ 0 ] ] command to clear the statistics. Then have the interface automatically collect the statistics.
Examples
# Clear the statistics on interface Null 0.
<Sysname> reset counters interface null 0
Related commands
display interface null
shutdown
Use shutdown to shut down a loopback interface.
Use undo shutdown to bring up a loopback interface.
Syntax
shutdown
undo shutdown
Default
A loopback interface is up.
Views
Loopback interface view
Predefined user roles
network-admin
mdc-admin
Usage guidelines
Use the shutdown command with caution, because the command disconnects the connection of the interface and disables the interface from communicating.
Examples
# Shut down interface loopback 1.
<Sysname> system-view
[Sysname] interface loopback 1
[Sysname-LoopBack1] shutdown
