Loopback-Detection Enable - H3C S7500E Series Command Reference Manual

Description
Use the loopback-detection control enable command to enable loopback detection control on trunk
or hybrid ports.
Use the undo loopback-detection control enable command to restore the default.
By default, loopback detection control is disabled on trunk and hybrid ports.
When a hybrid or trunk port detects a loop condition, it sends traps, whether loopback detection control
is enabled or not. However, only after loopback detection control is enabled, will the port perform the
protective action configured with the loopback-detection action command.
This command is not applicable to access ports.
Examples
# Enable loopback detection control on trunk port GigabitEthernet 2/0/1.
<Sysname> system-view
[Sysname] loopback-detection enable
[Sysname] interface gigabitEthernet 2/0/1
[Sysname-GigabitEthernet2/0/1] port link-type trunk
[Sysname-GigabitEthernet2/0/1] loopback-detection enable
[Sysname-GigabitEthernet2/0/1] loopback-detection control enable

loopback-detection enable

Syntax
loopback-detection enable
undo loopback-detection enable
View
System view, Ethernet interface view, port group view
Default Level
2: System level
Parameters
None
Description
Use the loopback-detection enable command to enable loopback detection globally in system view
or on ports in Ethernet interface or port group view. To use loopback detection on an Ethernet port, you
must enable the function both globally and on the port.
Use the undo loopback-detection enable command to disable loopback detection globally or on
ports.
The undo loopback-detection enable command in system view disables loopback detection on all
ports.
By default, loopback detection is disabled on all Ethernet ports.
If a port receives a packet that it sent out, a loop occurs. Loops may cause broadcast storms,
degrading network performance. You can use loopback detection to detect loops on a port and
configure the protective action to take on the port when a loop is detected, for example, to shut down
the port. In addition to the configured protective action, the switch also performs other actions to
alleviate the impact of the loop condition, as described in Table 1-11.
1-28