Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 33
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Configuring basic port parameters
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The line “Link Error Dampening” displays “Enabled” if port flap dampening is enabled on the port
or “Disabled” if the feature is disabled on the port. The feature is enabled on the ports in the two
examples above. Also, the characters “ERR-DISABLED” is displayed for the “GbpsEthernet” line if
the port is disabled because of link errors.
Syntax: show interface ethernet <port-number>
In addition to the show commands above, the output of the show interface brief command for
PowerConnect B-Series TI24X devices, indicates if a port is down due to link errors.
The ERR-DIS entry under the “Link” column indicates the port is down due to link errors.
Port loop detection
This feature allows the device to disable a port that is on the receiving end of a loop by sending test
packets. You can configure the time period during which test packets are sent.
Strict mode and loose mode
There are two types of loop detection; Strict Mode and Loose Mode. In Strict Mode, a port is
disabled only if a packet is looped back to that same port. Strict Mode overcomes specific
hardware issues where packets are echoed back to the input port. In Strict Mode, loop detection
must be configured on the physical port.
In Loose Mode, loop detection is configured on the VLAN of the receiving port. Loose Mode
disables the receiving port if packets originate from any port or VLAN on the same device. The VLAN
of the receiving port must be configured for loop detection in order to disable the port.
Recovering disabled ports
Once a loop is detected on a port, it is placed in Err-Disable state. The port will remain disabled
until one of the following occurs:
You manually disable and enable the port at the Interface Level of the CLI.
You enter the command clear loop-detection. This command clears loop detection statistics
and enables all Err-Disabled ports.