Spanning Tree Algorithm
103
Instruction Manual - NXA-ENET8-POE+
Configuring Loopback Detection
Use the Spanning Tree > Loopback Detection page to configure loopback detection on an interface. When loopback detection is
enabled and a port or trunk receives its own BPDU, the detection agent drops the loopback BPDU, sends an SNMP trap, and places
the interface in discarding mode. This loopback state can be released manually or automatically. If the interface is configured for
automatic loopback release, then the port will only be returned to the forwarding state if one of the following conditions is satisfied:
The interface receives any other BPDU except for its own, or;
The interface's link status changes to link down and then link up again, or;
The interface ceases to receive its own BPDUs in a forward delay interval.
NOTE:
If loopback detection is not enabled and an interface receives it's own BPDU, then the interface will drop the loopback BPDU
according to IEEE Standard 802.1w- 2001 9.3.4 (Note 1).
NOTE:
Loopback detection will not be active if Spanning Tree is disabled on the switch.
NOTE:
When configured for manual release mode, then a link down/up event will not release the port from the discarding state.
The following table lists the options on this page:
Perform these steps to configure loopback detection:
1.
Click
Spanning Tree
>
Loopback Detection
.
2.
Click
Port
or
Trunk
to display the required interface type.
3.
Modify the required loopback detection attributes.
4.
Click
Apply
Spanning Tree - Loopback Detection Options
Interface
Displays a list of ports or trunks.
Status
Enables loopback detection on this interface. (Default: Enabled)
Trap
Enables SNMP trap notification for loopback events on this interface. (Default: Disabled)
Release Mode
Configures the interface for automatic or manual loopback release. (Default: Auto)
Release
Allows an interface to be manually released from discard mode. This is only available if the
interface is configured for manual release mode.
Action
Sets the response for loopback detection to shut down the interface. (Default: Shutdown)
Shutdown Interval
The duration to shut down the interface. (Range: 60-86400 seconds; Default: 60 seconds)
If an interface is shut down due to a detected loopback, and the release mode is set to Auto, the
selected interface will be automatically enabled when the shutdown interval has expired.
If an interface is shut down due to a detected loopback, and the release mode is set to Manual, the
interface can be re-enabled using the Release button.
FIG. 112
Configuring Port Loopback Detection