Two functions are added to release 2107: configuring loopback detection for a list of ports in bulk, and enabling auto-shutdown of loopback ports.
Loopback detection is used to monitor if a port of a switch is looped back.
After you enable loopback detection on Ethernet ports, the switch can monitor if an external loopback occurs on them. If there is a loopback port found, the switch will deal with the loopback port according to your configuration.
1) If a loop is found on an access port, the system will set the port to the block state (ports in this state cannot forward data packets), send log messages to the terminal, and remove the corresponding MAC forwarding entry.
l If you have additionally enabled the loopback port auto-shutdown function on the port, the system will shut down the port, and send log messages to the terminal. After the loop is removed, you need to use the undo shutdown command to bring up the port.
l If you have not enabled the loopback port auto-shutdown function on the port, the port will automatically resume the normal forwarding state after the loop is removed.
2) If a loop is found on a trunk or hybrid port, the system sends log messages to the terminal. If you have additionally enabled the loopback port control function or the loopback port auto-shutdown function, the system will deal with the port accordingly:
l If the loopback port control function is enabled on the port, the system will set the port to the block state (ports in this state cannot forward data packets), send log messages to the terminal, and remove the corresponding MAC forwarding entry. After the loop is removed, the port will automatically resume the normal forwarding state.
l If the loopback port auto-shutdown function is enabled on the port, the system will shut down the port and send log messages to the terminal. After the loop is removed, you need to use the undo shutdown command to bring up the port.
You cannot enable both the loopback port control function and the loopback port auto-shutdown function on a port. If you do so, the function configured later will take effect.
Table 1-1 Configure loopback detection for Ethernet port(s)
Operation | Command | Remarks |
Enter system view | system-view | — |
Enable loopback detection globally | loopback-detection enable | Optional By default, the global loopback detection function is enabled if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled. |
Enable loopback detection on the specified ports in bulk | loopback-detection interface-list enable | Optional By default, the loopback detection function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled. At present, you can configure the loopback detection for ports in bulk on the S3100-EI series (except the S3100-EPON-EI series) switches and the E126A switch only. These switches are all shipped with a default configuration file (config.def). |
Set the interval for performing port loopback detection | loopback-detection interval-time time | Optional The default is 30 seconds. |
Enter Ethernet port view | interface interface-type interface-number | — |
Enable loopback detection on a specified port | loopback-detection enable | Optional By default, the loopback detection function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled. |
Enable loopback port control on the trunk or hybrid port | loopback-detection control enable | Optional By default, the loopback port control function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled. |
Enable the loopback port auto-shutdown function | loopback-detection shutdown enable | Optional By default, the loopback port auto-shutdown function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled. |
Configure the system to run loopback detection on all VLANs of the current trunk or hybrid port | loopback-detection per-vlan enable | Optional By default, the system runs loopback detection only on the default VLAN of the current trunk or hybrid port. |
Caution:
l To enable loopback detection on a specific port, you must use the loopback-detection enable command in both system view and the specific port view.
l After you use the undo loopback-detection enable command in system view, loopback detection will be disabled on all ports.
Syntax
loopback-detection control enable
undo loopback-detection control enable
View
Ethernet port view
Parameter
None
Description
Use the loopback-detection control enable command to enable the loopback port control function on the current trunk or hybrid port.
Use the undo loopback-detection control enable command to disable the loopback port control function on the trunk or hybrid port.
The loopback port control function works in conjunction with the loopback detection function (refer to loopback-detection enable). If a loop is found on a VLAN of the trunk or hybrid port:
l With the function enabled on the trunk or hybrid port, the system will set the port to the block state (ports in this state cannot forward data packets), send log messages to the terminal, and remove the corresponding MAC forwarding entry. After the loop is removed, the port will automatically resume the normal forwarding state.
l With the function disabled on the trunk or hybrid port, the system will only send log messages to the terminal, and the port is still in the normal forwarding state.
By default, the loopback port control function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled.
Note that this command is invalid for an access port.
Related command: loopback-detection enable.
Example
# Enable the loopback port control function on Ethernet 1/0/1.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] interface ethernet 1/0/1
[H3C-Ethernet1/0/1] port link-type trunk
[H3C-Ethernet1/0/1] loopback-detection control enable
Syntax
loopback-detection enable
undo loopback-detection enable
View
System view or Ethernet port view
Parameter
None
Description
Use the loopback-detection enable command to enable the loopback detection function on the current port to detect whether an external loopback occurs on the port.
Use the undo loopback-detection enable command to disable the loopback detection function on the port.
1) If a loop is found on an access port, the system will set the port to the block state (ports in this state cannot forward data packets), send log messages to the terminal, and remove the corresponding MAC forwarding entry.
l If you have enabled the loopback port auto-shutdown function (with the loopback-detection shutdown enable command) on the access port, the system will shut down the port, and send log messages to the terminal. After the loop is removed, you need to use the undo shutdown command to bring up the port.
l If you have not enabled the loopback port auto-shutdown function on the access port, the port will automatically resume the normal forwarding state after the loop is removed.
2) If a loop is found on a trunk or hybrid port, the system sends log messages to the terminal. If you have additionally enabled the loopback port control function or the loopback port auto-shutdown function, the system will deal with the port accordingly:
l If the loopback port control function is enabled on the port (with the loopback-detection control enable command), the system will set the port to the block state (ports in this state cannot forward data packets), send log messages to the terminal, and remove the corresponding MAC forwarding entry. After the loop is removed, the port will automatically resume the normal forwarding state.
l If the loopback port auto-shutdown function is enabled on the port (with the loopback-detection shutdown enable command), the system will shut down the port and send log messages to the terminal. After the loop is removed, you need to use the undo shutdown command to bring up the port.
The loopback detection function on a specific port can take effect only after you enable the loopback detection function globally (in system view) and on the port (in the specified port view).
By default, the loopback detection function is enabled globally and on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled.
Related command: loopback-detection control enable, loopback-detection shutdown enable.
Example
# Enable the loopback detection function on Ethernet 1/0/1.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] loopback-detection enable
[H3C] interface ethernet 1/0/1
[H3C-Ethernet1/0/1] loopback-detection enable
Syntax
loopback-detection interface-list enable
undo loopback-detection interface-list enable
View
System view
Parameter
interface-list: Ethernet port list, in the form of interface-list = { interface-type interface-number [ to interface-type interface-number ] } &<1-10>, where
l interface-type is the port type, and interface-number is the port number.
l Keyword to is used to specify a range of ports. The port number after to must be equal to or greater than that before to.
l &<1-10> means that you can specify up to 10 ports or port ranges.
Description
Use the loopback-detection interface-list enable command to enable the loopback detection function on a range of ports.
Use the undo loopback-detection interface-list enable command to disable the loopback detection function on a range of ports.
By default, the loopback detection function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled.
At present, you can configure the loopback detection for ports in bulk on the S3100-EI series (except the S3100-EPON-EI series) switches and the E126A switch only. These switches are all shipped with a default configuration file (config.def).
Example
# Enable the loopback detection function on ports Ethernet 1/0/1 through Ethernet 1/0/4.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] loopback-detection enable
[H3C] loopback-detection Ethernet 1/0/1 to Ethernet 1/0/4 enable
Syntax
loopback-detection interval-time time
undo loopback-detection interval-time
View
System view
Parameter
time: Time interval for loopback detection, in the range of 5 to 300 (in seconds). It is 30 seconds by default.
Description
Use the loopback-detection interval-time command to set time interval for loopback detection.
Use the undo loopback-detection interval-time command to restore the default time interval.
Example
# Set time interval for loopback detection to 10 seconds.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] loopback-detection interval-time 10
Syntax
loopback-detection per-vlan enable
undo loopback-detection per-vlan enable
View
Ethernet port view
Parameter
None
Description
Use the loopback-detection per-vlan enable command to configure the system to run loopback detection on all VLANs of the current trunk or hybrid port.
Use the undo loopback-detection per-vlan enable command to restore the default setting.
By default, the system runs loopback detection only on the default VLAN of the trunk or hybrid port.
Note that the command is invalid for any access port.
Example
# Configure the system to run loopback detection on all VLANs of the trunk port Ethernet1/0/1.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] interface ethernet 1/0/1
[H3C-Ethernet1/0/1] port link-type trunk
[H3C-Ethernet1/0/1] loopback-detection per-vlan enable
Syntax
loopback-detection shutdown enable
undo loopback-detection shutdown enable
View
Ethernet port view
Parameter
None
Description
Use the loopback-detection shutdown enable command to enable the loopback port auto-shutdown function.
Use the undo loopback-detection shutdown enable command to disable the function.
The loopback port auto-shutdown function works in conjunction with the loopback detection function (refer to loopback-detection enable). If a loop is found at a port:
l With the function enabled on the port, the system will shut down the port, and send log messages to the terminal. After the loop is removed, you need to use the undo shutdown command to bring up the port.
l With the function disabled on the port, the system will only send log messages to the terminal, and the port is still in the normal forwarding state.
By default, the loopback port auto-shutdown function is enabled on ports if the device boots with the default configuration file (config.def); if the device boots with null configuration, this function is disabled.
You cannot enable both the loopback port control function (with the loopback-detection control enable command) and the loopback port auto-shutdown function on a port. If you do so, the function configured later will take effect.
Related command: loopback-detection enable, loopback-detection control enable.
Example
# Enable the loopback port auto-shutdown function on port Ethernet 1/0/1.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] loopback-detection enable
[H3C] interface ethernet 1/0/1
[H3C-Ethernet1/0/1] loopback-detection shutdown enable
