Install Guide

storm-control pfc-llfc pps in shutdown
NOTE: PFC/LLFC storm control enabled interface disables the interfaces if it receives continuous PFC/LLFC packets.
It can be a result of a faulty NIC/Switch that sends spurious PFC/LLFC packets.
Configuring Storm Control from CONFIGURATION Mode
To configure storm control from CONFIGURATION mode, use the following command.
From CONFIGURATION mode you can configure storm control for ingress and egress traffic.
Do not apply per-virtual local area network (VLAN) quality of service (QoS) on an interface that has storm-control enabled
(either on an interface or globally).
● Configure storm control.
CONFIGURATION mode
● Configure the packets per second of broadcast traffic allowed in the network.
CONFIGURATION mode
storm-control broadcast packets_per_second in
● Configure the packets per second (pps) of multicast traffic allowed on C-Series and S-Series networks only.
CONFIGURATION mode
storm-control multicast packets_per_second in
● Configure the packets per second of unknown-unicast traffic allowed in or out of the network.
CONFIGURATION mode
storm-control unknown-unicast packets_per_second in
Detect PFC Storm
The following section explains the procedure to detect the PFC storm.
You can detect the PFC storm by polling the lossless queues in a port or priority periodically. When the queue depth is not equal
to zero or when the queue has traffic after subsequent number of polling, then the port or priority is detected to have the PFC
storm.
● Use the polling—interval {interval in milli-seconds} command to set the polling interval. The queue traffic
and egress counters are polled.
● Use the xoff-state threshold polling-count {number of polling-interval} command to set the
number of times the polling should be done. If the traffic and the egress counter remain the same after the subsequent
polling, then the corresponding port or priority is detected to have PFC storm.
● Once PFC storm is detected on an interface, you can use the storm-control pfc in queue-drop command on the
interface to drop the ingress packets. This command triggers a queue drop state on the interface with PFC storm, so that
the traffic through other ports and priorities are not affected.
For more information about the above commands, see the Dell EMC Networking OS Command Line Reference Guide.
Restore Queue Drop State
You can restore the queue drop triggered due to the storm control PFC detection to the normal state.
Once the storm control PFC is detected on a port or priority, you can activate the queue drop action. You can restore the
dropped queue to normal state on the following conditions.
● You can restore the queue after a particular period of time. Use the queue-drop backoff-force polling—count
command to remove the queue-drop state after the specified number of polling is done. The queue-drop state, which has
been activated due to the detection of storm control PFC, is forced to get removed. When the number of polling-interval
is set as ‘zero’, the queue-drop state is not removed until it is explicitly cleared using the storm-control pfc in
queue-drop-state clear command.
● You can restore the queue when additional PFC packets for a particular priority are not received for a specified period
of time. Use the queue-drop backoff-on-norxpfc polling-count command to remove the queue-drop state if
additional PFCs are not received after the specified number of polling is done.
Storm Control
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