Storm Control on Trunks

[graham-lewis]

Hi,

I’ve been doing some research into implementing storm control across an enterprise network and have come across some excellent articles. One comment to an article stated (paraphrased):

“1) One very important remark everybody seems to miss, is that storm-control only works on INBOUND packets. It does not prevent a port from being overwhelmed with broadcasts from the core or distribution. [assuming only configured on access ports]

2) Watch out with storm control on trunk ports! What is a broadcast on a trunk? In any "allowed-vlan"? No, any broadcast in any vlan, even non-allowed.

2b) The storm-control "drop filter" action will block on all VLANS.”

Please could someone confirm whether this is true and point me in the direction of any Cisco documentation that details this behaviour?

I ask because I’m concerned that a broadcast storm on one VLAN could cause broadcast traffic to be dropped on a completely unrelated trunk.

TIA

[Philip D'Ath]

I'm not a huge fan of storm control, as I have seen people use and can break network worse than the trouble caused by the storms.

Having said that, I have used it ... what I do is take the normal maximum for that port, and multiply it by 10.  Then it has to be significantly higher than it has even been before - aka a real problem.

[graham-lewis]

Thanks Philip, I will bear that in mind.