Configuration Guide User guide

FastIron Configuration Guide 65
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Basic port parameter configuration
NOTE
If a port name is longer than five characters, the port name is truncated in the output of the show
interface brief command.
Syslog messages for port flap dampening
The following Syslog messages are generated for port flap dampening.
• If the threshold for the number of times that a port link toggles from “up” to “down” then
“down” to “up” has been exceeded, the following Syslog message is displayed.
0d00h02m10s:I:ERR_DISABLE: Link flaps on port ethernet 16 exceeded threshold;
port in err-disable state
• If the wait time (port is down) expires and the port is brought up the following Syslog message
is displayed.
0d00h02m41s:I:ERR_DISABLE: Interface ethernet 16, err-disable recovery timeout
Port loop detection
This feature allows the Brocade 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.
Types of loop detection
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.
• The device automatically re-enables the port. To set your device to automatically re-enable
Err-Disabled ports, refer to “Configuring the device to automatically re-enable ports” on
page 67.
Port loopback detection configuration notes
• Loopback detection packets are sent and received on both tagged and untagged ports.
Therefore, this feature cannot be used to detect a loop across separate devices.
The following information applies to Loose Mode loop detection: