storm control - clarify effect of default action please

[sossie]

Hello,

I would like to have the default action clarified for storm control on a catalyst switch.

Say I have this configured on a 1Gig switchport:

storm-control broadcast level 10

(with the default action)

Can someone please clarify if with the default action configured:

Once broadcast reaches 100Mbit/s (approx)

The storm control will filter/block all broadcast traffic into that interface

or

storm control will rate limit all broadcast traffic at 100Mb/s into that interface.

What happens if storm control is configured on a trunk port?

Will it filter all broadcasts on all vlans?

[Madhukrishnan Gopinathan Nair]

Hello Simon,

It is not actually reate-limiting. When it reaches the threshold, it will drop all further broadcast for the storm-control interval(I think it is 1 sec by default)

traffic storm control (also called traffic suppression) allows you to monitor the levels of the incoming broadcast, multicast, and unicast traffic over a 1-second interval. During this interval, the traffic level, which is a percentage of the total available bandwidth of the port, is compared with the traffic storm control level that you configured. When the ingress traffic reaches the traffic storm control level that is configured on the port, traffic storm control drops the traffic until the interval ends.“

[Madhukrishnan Gopinathan Nair]

Also here is the characteristics of storm-control.

The following are examples of traffic storm control behavior:

•If you enable broadcast traffic storm control, and broadcast traffic exceeds the level within a 1-second traffic storm control interval, traffic storm control drops all broadcast traffic until the end of the traffic storm control interval.

•If you enable broadcast and multicast traffic storm control, and the combined broadcast and multicast traffic exceeds the level within a 1-second traffic storm control interval, traffic storm control drops all broadcast and multicast traffic until the end of the traffic storm control interval.

•If you enable broadcast and multicast traffic storm control, and broadcast traffic exceeds the level within a 1-second traffic storm control interval, traffic storm control drops all broadcast and multicast traffic until the end of the traffic storm control interval.

•If you enable broadcast and multicast traffic storm control, and multicast traffic exceeds the level within a 1-second traffic storm control interval, traffic storm control drops all broadcast and multicast traffic until the end of the traffic storm control interval.

Regarding your question on trunk, i think it does not differentiate between Vlans, as the total traffic value is being compared.

Hope this helps

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[Madhukrishnan Gopinathan Nair]

Hello Simon,

Do you have any more questions on this? 

Thanks,

Madhu