Loopback Detection Settings - D-Link xStack DGS-3420 Series Reference Manual

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch Web UI Reference Guide

Loopback Detection Settings

The Loopback Detection (LBD) function is used to detect the loop created by a specific port. This feature is used to
temporarily shut down a port on the Switch or block traffic through specific VLANs when a CTP (Configuration
Testing Protocol) packet has been looped back to the Switch. When the Switch detects CTP packets received from
a port or a VLAN, this signifies a loop on the network. The Switch will automatically block the port or the VLAN and
send an alert to the administrator. The Loopback Detection port will restart (change to normal state) when the
Loopback Detection Recover Time times out. The Loopback Detection function can be implemented on a range of
ports at a time. The user may enable or disable this function using the drop-down menu.
To view this window, click Security > Loopback Detection Settings as shown below:
The fields that can be configured are described below:
Parameter
Loopback Detection
State
Mode
Trap State
Log State
Interval (1-32767)
Recover Time (0 or 60-
1000000)
Unit
From Port / To Port
Figure 8-58 Loopback Detection Settings window
Description
Use the radio button to enable or disable loopback detection. The default is
Disabled.
Use the drop-down menu to toggle between Port-based and VLAN-based.
Use the drop-down menu to set the desired trap status: None, Loop Detected, Loop
Cleared, or Both.
Use the drop-down menu to enable or disable the state of the log for loopback
detection.
The time interval (in seconds) that the device will transmit all the CTP (Configuration
Test Protocol) packets to detect a loop-back event. The valid range is from 1 to
32767 seconds. The default setting is 10 seconds.
Time allowed (in seconds) for recovery when a Loopback is detected. The Loop-
detect Recover Time can be set at 0 seconds, or 60 to 1000000 seconds. Entering 0
will disable the Loop-detect Recover Time. The default is 60 seconds.
Select the unit you wish to configure.
Select a range of ports to use for this configuration.
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