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Understanding Storm Control on a Junos Fusion Enterprise

Storm control enables the switch to monitor traffic levels and to drop broadcast, multicast, and unknown unicast packets when a specified traffic level—known as the storm control level or storm control bandwidth—is exceeded, preventing the packets from proliferating and degrading service. As an alternative to having the switch drop packets, you can configure storm control to shut down interfaces or temporarily disable interfaces when the storm control level is exceeded.

Storm control configuration in a Junos Fusion Enterprise is identical for a standalone EX9200 switch. For more information, see Understanding Storm Control for Managing Traffic Levels on Switching Devices.

In a Junos Fusion Enterprise with dual aggregation devices there are special considerations that impact storm control functionality. The following requirements should be understood when configuring storm control for a Junos Fusion Enterprise:

  • Broadcast, multicast, and unknown unicast packets received on the extended port of a satellite device can be forwarded to two different aggregation devices, so the storm control profile is applied to the cumulative traffic reaching a particular aggregation device, not the cumulative traffic received on the extended port of the satellite device.

  • If the storm control level is exceeded and the resulting action is to shut down the port, the aggregation device which detects the storm brings down the extended port, and the status is synced to the peer aggregation device.

  • The shutdown is applied at the physical interface level; in a standalone EX9200 switch, storm control shutdown is applied at the logical interface level.

  • Executing the clear ethernet-switching recovery-timeout command on one aggregation device also clears the error on the other aggregation device.

  • In the event of a shutdown, if the recovery timer is configured, the error is cleared on both aggregation devices when the timer expires.