Dell Command Line Reference Guide for the S4048–ON System


Storm Control

The Dell EMC Networking OS storm control feature allows you to limit or suppress traffic during a traffic storm (Broadcast/Unknown Unicast Rate Limiting or Multicast on the C-Series and S-Series).

Storm control is supported on Dell EMC Networking OS.

Important Points to Remember

  • Interface commands can only be applied on physical interfaces (virtual local area networks [VLANs] and link aggregation group [LAG] interfaces are not supported).
  • An INTERFACE-level command only supports storm control configuration on ingress.
  • An INTERFACE-level command overrides any CONFIGURATION-level ingress command for that physical interface, if both are configured.
  • You can apply the CONFIGURATION-level storm control commands at ingress or egress and are supported on all physical interfaces.
  • When storm control is applied on an interface, the percentage of storm control applied is calculated based on the advertised rate of the line card. It is not based on the speed setting for the line card.
  • Do not apply per-VLAN quality of service (QoS) on an interface that has storm control enabled (either on an interface or globally).
  • When you enable broadcast storm control on an interface or globally on ingress, and DSCP marking for a DSCP value 1 is configured for the data traffic, the traffic goes to queue 1 instead of queue 0.
  • Similarly, if you enable unicast storm control on an interface or globally on ingress, and DSCP marking for a DSCP value 2 is configured for the data traffic, the traffic goes to queue 2 instead of queue 0.
NOTE: Bi-directional traffic (unknown unicast and broadcast) along with egress storm control causes the configured traffic rates split between the involved ports. The percentage of traffic that each port receives after the split is not predictable. These ports can be in the same/different port pipes or the same/different line cards.
NOTE: After applying the storm-control configuration, traffic drop is expected if ingress traffic follows a burst pattern. For example, storm-control broadcast 1000 in. This configuration allows the switch to forward only 1 packet per millisecond. If a higher number of packets ingress at the switch interface within a duration of 1 millisecond, the switch forwards the first packet and drops the remaining packets.
NOTE: The policy discard drop counters are common across storm-control drops, ACL drops and QoS drops. If your configuration includes ACL and QoS, those drops are also computed and displayed in the policy discard drops counter field along with storm-control drops. The packets dropped by the storm control feature can be monitored by viewing the value of the Policy Discard Drops field of the output of the show hardware stack-unit stack—unit—number drops command.

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