ECS4100 Series CLI Reference Guide-R07

Chapter 16 | Loopback Detection Commands
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bcast-discared - When a loopback condition on a specific port is detected,
all received packets at the port are dropped.
block - When a loopback is detected on a port which a member of a
specific VLAN, packets belonging to that VLAN are dropped at the
offending port.
none - No action is taken.
port-disable -When a loopback condition on a specific port is detected,
packet transmission and reception at the port is disabled with the port
physical link status in the up condition.
shutdown - Shuts down the interface.
Default Setting
Shut down
Command Mode
Global Configuration
Command Usage
◆ When the response to a detected loopback condition is set to block user traffic,
loopback detection control frames may be untagged or tagged depending on
the port’s VLAN membership type.
◆ When the response to a detected loopback condition is set to block user traffic,
ingress filtering for the port is enabled automatically if not already enabled by
the switchport ingress-filtering command. The port’s original setting for ingress
filtering will be restored when loopback detection is disabled.
◆ When a port receives a control frame sent by itself, this means that the port is in
looped state, and the VLAN in the frame payload is also in looped state with the
wrong VLAN tag. The looped port is therefore shut down.
◆ Use the loopback-detection recover-time command to set the time to wait
before re-enabling an interface shut down by the loopback detection process.
◆ When the loopback detection response is changed, any ports placed in
shutdown state by the loopback detection process will be immediately
restored to operation regardless of the remaining recover time.
Example
This example sets the loopback detection mode to shut down user traffic.
Console(config)#loopback-detection action shutdown
Console(config)#