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C6500 Storm control - Different level for Broadcast & Multicast



we configured broadcast storm control on our C6500. We would like now to add multicast storm control, but with another value (bigger) than for broadcast.

The problem is when I configure multicast level, it changes automatically the value for broadcast.

Is it a way to avoid that?




Reza Sharifi
Hall of Fame Expert Hall of Fame Expert
Hall of Fame Expert


That is a normal behavior.  If you configure broadcast at 5% and than later configure multicast at 7%, the router will change the broadcast to 7%.

have a look at this example:

This example shows how the traffic storm control level configured for one mode affects all other modes that are already configured on the Gigabit Ethernet interface 4/10:

Router# show run inter gig4/10

Building configuration...

Current configuration : 176 bytes


Router# interface GigabitEthernet4/10

Router# switchport 

Router# switchport mode access

Router# storm-control broadcast level 0.5

Router# storm-control multicast level 0.5

Router# spanning-tree portfast edge 

Router# end

Router# configure terminal

Router(config)# interface gigabitethernet 4/10 

Router(config-if)# storm-control unicast level 0.7 

Router(config-if)# end

Router# show interfaces gig4/10 counters storm-control

Port UcastSupp % McastSupp % BcastSupp % TotalSuppDiscards 

Gi4/10 00.70 00.70 00.70 0 


config guide:


This behavior is not really nice as broadcast traffic is normally less important that multicast.

If I have, let's say, video on my network, I would like to have a limit of 50 Mbps for multicast.

Beside that, I want my have a broadcast limit of  5Mbps, to protect my CPU.

Is there a solution?

Hi! This thread is quite old, but maybe somebody will still read it. As you can see from the output, the same value applies to UNICAST traffic also, and that's a problem! This is an obvious bug. Is there any solution to it? Best regards.

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