DGS-6604
m
loopback-detection (global)
CLI Reference Guide
410
loopback-detection (global)
Use the command to enable global loopback detection function. Use
no
form to
disable the function.
loopback-detection
no loopback-detection
Syntax
None
Default
Disabled
Command Mode
Configuration mode
Usage Guideline
Used to enable or disable the LBD function globally.
When a port enables the loopback-detection function, and switch is in forwarding
state, will periodically sends out CTP packets with the SA field set to device's
MAC, DA field set to CF-00-00-00-00-00. Type is "90-00". If the port is an
untagged member of a VLAN, this port will send out the untagged CTP packet. If
the port is only tagged member of VLAN, then this port will send out the tagged
packet with one of the VLAN ID to which this port belonged.
When the switch detects that a CTP packet sent out by the port has been looped
back to the packet originating port, it will put this port into error disabled state or
block the traffic which belong to this VLAN according to the detection mode user
configured. There are two kinds of recovery mechanisms provide, user can bring
it out of this state by entering the "errdisable recovery cause loopback-detection"
global configuration command. Alternatively, the user can manually re-enable the
port by entering the "shutdown" then "no shutdown" command in interface-
configuration mode.
Example
This example shows how to enable loopback detection function.
You can verify your settings by entering the show loopback-detection command.
Switch(config)# loopback-detection
Switch(config)#