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Storm Control

Storm control provides protection against excessive inbound BUM (broadcast, unknown unicast, multicast) traffic on layer 2 switch port interfaces, which can cause poor network performance.

  • Storm control is not supported on a switch with the Tomahawk2 ASIC.
  • On Broadcom switches, ARP requests over layer 2 VXLAN bypass broadcast storm control; they are forwarded to the CPU and subjected to embedded control plane QoS instead.

Configure Storm Control

To configure storm control for physical ports, edit the /etc/cumulus/switchd.conf file. For example, to enable broadcast storm control for swp1 at 400 packets per second (pps), multicast storm control at 3000 pps, and unknown unicast at 500 pps, edit the /etc/cumulus/switchd.conf file and uncomment the storm_control.broadcast, storm_control.multicast, and storm_control.unknown_unicast lines:

cumulus@switch:~$ sudo nano /etc/cumulus/switchd.conf
# Storm Control setting on a port, in pps, 0 means disable
interface.swp1.storm_control.broadcast = 400
interface.swp1.storm_control.multicast = 3000
interface.swp1.storm_control.unknown_unicast = 500

When you update the /etc/cumulus/switchd.conf file, you must restart switchd for the changes to take effect.

cumulus@switch:~$ sudo systemctl restart switchd.service

Restarting the switchd service causes all network ports to reset, interrupting network services, in addition to resetting the switch hardware configuration.

Alternatively, you can run the following commands. The configuration below takes effect immediately, but does not persist if you reboot the switch. For a persistent configuration, edit the /etc/cumulus/switchd.conf file, as described above.

cumulus@switch:~$ sudo sh -c 'echo 400 > /cumulus/switchd/config/interface/swp1/storm_control/broadcast'
cumulus@switch:~$ sudo sh -c 'echo 3000 > /cumulus/switchd/config/interface/swp1/storm_control/multicast'
cumulus@switch:~$ sudo sh -c 'echo 500 > /cumulus/switchd/config/interface/swp1/storm_control/unknown_unicast'

To use the same command above on range of interfaces you can use a for-loop from the switch CLI using the below example.

cumulus@switch:mgmt:~$ for i in {1..5}; do
> sudo sh -c "echo 400 > /cumulus/switchd/config/interface/swp$i/storm_control/broadcast"
> sudo sh -c "echo 3000 > /cumulus/switchd/config/interface/swp$i/storm_control/multicast"
> sudo sh -c "echo 500 > /cumulus/switchd/config/interface/swp$i/storm_control/unknown_unicast"
> done