← All lab tasks Network Access Fix · Medium ~12 min · 3 devices · 5 tasks · CCNA v2.0
Storm control: cap broadcasts on access ports and recover err-disabled An IoT sensor plugged into Fa0/5 sends a steady stream of broadcasts that saturate VLAN 20. Users on PC1 (Fa0/1) are complaining the whole LAN is slow. Enable storm-control for broadcast at 1.00 percent on all access ports (Fa0/1 through Fa0/10), set the violation action to shutdown so the offender gets err-disabled, and set auto-recovery for cause storm-control so the port comes back after five minutes without a manual reset.
SW1 Fa0/1 -> PC1 (user)
Tasks ○ Apply storm-control broadcast level 1.00 on Fa0/1 ○ Apply storm-control broadcast level 1.00 on Fa0/5 (the offender) ○ Set the action to shutdown on Fa0/5: storm-control action shutdown ○ Enable auto-recovery for the cause: errdisable recovery cause storm-control ○ Set interval to 300 seconds: errdisable recovery interval 300 ✓ Network fixed.
Broadcasts are capped per port. A port that exceeds the threshold err-disables and auto-recovers after five minutes.
Hints (open one at a time) Hint 1: unit of measure The level is a percentage of interface bandwidth. On a 100 Mbps port, level 1.00 caps broadcast at ~1 Mbps. You can also give it in pps or bps with keywords; the exam uses the percentage form.
Hint 2: the action Without storm-control action shutdown, the port silently drops the excess but stays up. Shutdown makes the problem visible and lets err-disable recovery clean it up.
Hint 3: recovery err-disable recovery needs two things: the cause enabled (errdisable recovery cause storm-control) and an interval. Default interval is 300 seconds.
Full solution SW1# configure terminal
SW1(config)# interface range Fa0/1 - 10
SW1(config-if-range)# storm-control broadcast level 1.00
SW1(config-if-range)# exit
SW1(config)# interface Fa0/5
SW1(config-if)# storm-control action shutdown
SW1(config-if)# exit
SW1(config)# errdisable recovery cause storm-control
SW1(config)# errdisable recovery interval 300
SW1(config)# end
SW1# show storm-control broadcastStorm control also exists for multicast and unknown-unicast traffic. For a mixed VoIP + IoT environment, add storm-control multicast level pps 1000 on the IoT ports so legitimate multicast on voice ports is not affected.
