H3C LS-S3100-8C-SI-DC-OVS, LS-S3100-26C-SI-AC-OVS, S3100 16C SI User Manual
H3C Loopback Detection Feature Manual
Release 2107 Table of Contents
Table of Contents
Chapter 1 Loopback Detection Configuration............................................................................ 1-1
1.1 Loopback Detection Configuration.....................................................................................1-1
1.1.1 Loopback Detection Overview ................................................................................1-1
1.1.2 Configuring Loopback Detection for Ethernet Port(s).............................................1-2
Chapter 2 Loopback Detection Configuration Commands.......................................................2-1
2.1 Loopback Detection Configuration Commands................................................................. 2-1
2.1.1 loopback-detection control enable ..........................................................................2-1
2.1.2 loopback-detection enable......................................................................................2-2
2.1.3 loopback-detection interface-list enable..................................................................2-4
2.1.4 loopback-detection interval-time .............................................................................2-5
2.1.5 loopback-detection per-vlan enable........................................................................2-5
2.1.6 loopback-detection shutdown enable...................................................................... 2-6
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H3C Loopback Detection Feature Manual
Release 2107 Chapter 1 Loopback Detection Configuration
Chapter 1 Loopback Detection Configuration
Note:
Two functions are added to release 2107: configuring loopback detection for a list of
ports in bulk, and enabling auto-shutdown of loopback ports.
1.1 Loopback Detection Configuration
1.1.1 Loopback Detection Overview
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.
z 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 bri ng
up the port.
z 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:
z 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.
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H3C Loopback Detection Feature Manual
Release 2107 Chapter 1 Loopback Detection Configuration
z 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.
Note:
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.
1.1.2 Configuring Loopback Detection for Ethernet Port(s)
Table 1-1 Configure loopback detection for Ethernet port(s)
Operation Command Remarks
Enter system view
Enable loopback
detection globally
Enable loopback
detection on the
specified ports in
bulk
system-view
loopback-detection
enable
loopback-detection
interface-list 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.
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
Enter Ethernet port
view
loopback-detection
interval-time time
interface interface-type
interface-number
1-2
Optional
The default is 30 seconds.
—
H3C Loopback Detection Feature Manual
Release 2107 Chapter 1 Loopback Detection Configuration
Operation Command Remarks
Optional
By default, the loopback
Enable loopback
detection on a
specified port
loopback-detection
enable
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.
Optional
By default, the loopback port
Enable loopback
port control on the
trunk or hybrid port
loopback-detection
control enable
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.
Optional
By default, the loopback port
auto-shutdown function is
Enable the loopback
port auto-shutdown
function
loopback-detection
shutdown enable
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:
z 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.
z After you use the undo loopback-detection enable command in system view,
loopback detection will be disabled on all ports.
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