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15
Loopback Detection Commands
The switch can be configured to detect general loopback conditions caused by
hardware problems or faulty protocol settings. When enabled, a control frame
is transmitted on the participating ports, and the switch monitors inbound
traffic to see if the frame is looped back.
Usage Guidelines
◆
The default settings for the control frame transmit interval and recover time
may be adjusted to improve performance for your specific environment.
The shutdown mode may also need to be changed once you determine
what kind of packets are being looped back.
◆
General loopback detection provided by the commands described in this
section and loopback detection provided by the spanning tree protocol
cannot both be enabled at the same time. If loopback detection is enabled
for the spanning tree protocol, general loopback detection cannot be
enabled on the same interface.
◆
When a loopback event is detected on an interface or when a interface is
released from a shutdown state caused by a loopback event, a trap
message is sent and the event recorded in the system log.
◆
Loopback detection must be enabled both globally and on an interface for
loopback detection to take effect.
Table 82: Loopback Detection Commands
Command
Function
Mode
Enables loopback detection globally on the
switch or on a specified interface
GC, IC
Specifies the response to take for a detected
loopback condition
GC
Specifies the interval to wait before releasing an
interface from shutdown state
GC
Specifies the interval at which to transmit
loopback detection control frames
GC
Configures the switch to send a trap when a
loopback condition is detected or the switch
recover from a loopback
GC
Manually releases all interfaces currently shut
down by the loopback detection feature
PE
Shows loopback detection configuration settings
for the switch or for a specified interface
PE