Controlling broadcasts on edge access switches

[rgnwcco]

How can I configure my edge access switches 3500XL, 2900XL, 3550 etc to disable a port if it generates too many broadcasts (broadcast storm).

[sundar.palaniappan]

See the example below.

Switch(config)# interface fastethernet0/1

Switch(config-if)# storm-control broadcast level 20

Switch(config-if)# storm-control action shutdown

In this example, switch will set the port to error-disable state when the broadcast traffic level reaches 20% of the total bandwidth of the interface.

Make sure, you take into account the protcols or applications that require broadcast before deciding on the level.

HTH,

Sundar

[rgnwcco]

Is there any average level that one can use for this configuration on a standard enterprise network?

[sundar.palaniappan]

There's no standard level. It varies from network to network.

It depends on the type of protocols or applications you are using. Some protocols are chatty in nature, like, IPX RIP, AT, Multicasting etc. and hence, the need to allow more broadcast traffic becomes inevitable.

HTH,

Sundar

[eringaard]

Storm-control is the easiest implementation, but is not supported on all switches. It's really the question of how much you want to worry about it, using the for a more advanced implementation this really is a part of Qos which you might want to look into. Some cisco switch types may even seperate broadcast from unicast traffic by default in their in/egress queue, so that broadcasts can never flood unicast traffic. But qos is fairly complicated and configuration is different on almost every switch type/model and/or software version. Still it might be worth looking into.