Port Management
Loopback Detection
Cisco 220 Series Smart Switches Administration Guide Release 1.1.0.x
111
9
-
DHCP Rate Limit
—Check
Enable
to enable the timer to recover from the
DHCP rate limit causes.
-
Loopback Detection
—Check
Enable
to enable the timer to recover from
the Loopback Detection causes.
-
PoE
—(Only applicable for PoE models) Check
Enable
to enable the timer
to recover from the Power over Ethernet (PoE) causes.
-
Port Security
—Check
Enable
to enable the timer to recover from the port
security causes.
-
Self Loop
—Check
Enable
to enable the timer to recover from the
selfloop cause.
-
Unicast Flood
—Check
Enable
to enable the timer to recover from the
Unicast flood causes.
-
Unknown Multicast Flood
—Check
Enable
to enable the timer to recover
from the unknown Multicast flood causes.
STEP 3
Click
Apply
. The
error recovery settings are modified, and the Running
Configuration is updated.
STEP 4
The
Suspended (errDisabled) Interface Table
displays a list of suspended ports.
To manually reactivate a suspended port, select the desired port, and click
Reactivate
.
Loopback Detection
Loopback Detection (LBD) provides protection against loops by transmitting loop
protocol packets out of ports on which loop protection has been enabled. When
the switch sends out a loop protocol packet, and then receives the same packet, it
shuts down the port that received the packet.
Loopback Detection operates independently of STP. After a loop is discovered,
the port that received the loops is placed in the Shut Down state. A trap is sent
and the event is logged. Network managers can define a Detection Interval that
sets the time interval between LBD packets.
The following loop cases can be detected by the Loopback Detection protocol:
•
Shorted wire—Port that loop backs all receiving traffic.