Setup Guide

storm-control multicast packets_per_second in
• Shut down the port if it receives the PFC/LLFC packets more than the configured rate.
INTERFACE mode
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
PFC Storm
When packets flood a network, the result is excessive traffic which affects the performance of the network. When Priority Flow Control
(PFC) is enabled on a port, the traffic flows according to the priority of the data.
Limitation: Dell EMC Networking OS does not support storm-control pfc, when the policy map uses trust diffserv for packet
classification.
PFC storm is the inconsistencies found in the traffic that flows through a PFC enabled port. You can detect this by polling the lossless
queues on each port. This polling is done at periodic intervals. If the queue has traffic with the corresponding egress counter not getting
incremented, then the condition is detected as PFC storm. During such conditions, the traffic corresponding to the port or priority can be
dropped for a specific period of time to overcome the degrade in the network performance.
Once you detect PFC storm on a port or priority, you can discard all packets on that port/priority and enable drop of the queue, so that
traffic corresponding to other priorities is not affected. You can restore the dropped queue to normal state after a period of time.
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.
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Storm Control