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This feature periodically detects whether the device is in the PFC deadlock state. If an interface is
always in the PFC XOFF state within the PFC deadlock detection interval, the device enters the PFC
deadlock state. If PFC deadlock detection is recovered in automatic mode, the device automatically
releases the deadlock state and recovers PFC and PFC deadlock detection after the delay timer
expires. During the delay timer period, the device disables PFC and PFC deadlock detection on the
interface, so that packets can be forwarded properly.
After the PFC deadlock state is released, the PFC deadlock detection feature can be recovered on
the interface in automatic or manual mode. Recovering this feature enables the PFC feature again at
the same time. Use the automatic recovery mode when no serious failures occur.
When a packet loop cannot be eliminated and the device enters PFC deadlock state frequently,
manually recover PFC deadlock detection on the interface as follows:
1.
Perform troubleshooting and set the manual recovery mode for PFC deadlock detection.
2.
Execute the
priority-flow-control deadlock recover
command to recover the
PFC deadlock detection and PFC features.
Restrictions and guidelines
The specified CoS value must be within the 802.1p priority list specified by using the
priority-flow-control no-drop dot1p
command. To view the 802.1p priority for each
CoS value, execute the
display qos map-table dot1p-lp
command.
Prerequisites
Before you configure PFC deadlock detection on an Ethernet interface, complete the following tasks:
•
Enable PFC in auto mode or forcibly on the Ethernet interface.
•
Enable PFC for 802.1p priorities on the Ethernet interface.
Procedure
1.
Enter system view.
system-view
2.
Set the precision for the PFC deadlock detection timer.
priority-flow-control deadlock precision
{
high
|
normal
|
low
}
By default, the PFC deadlock detection timer uses normal precision.
3.
Set the PFC deadlock detection interval for the specified CoS value.
priority-flow-control deadlock cos
cos-value
interval
interval
By default, the PFC deadlock detection interval is not set.
4.
Configure the delay timer for PFC deadlock detection automatic recovery.
priority-flow-control deadlock auto-recover
cos
cos-value delay
delay-time
By default, the delay timer for PFC deadlock detection automatic recovery is not configured.
5.
Configure the action to take on packets during the delay timer period for PFC deadlock
automatic recovery.
priority-flow-control deadlock auto-recover action
{
discard
|
forwarding
}
By default, the device forwards received data packets during the delay timer period for PFC
deadlock detection automatic recovery.
6.
Configure the upper threshold for PFC deadlock times during the specified period.
priority-flow-control deadlock threshold cos
cos-value
period
period
count
count
By default, the upper threshold for PFC deadlock times during the specified period is not
configured.
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