Storm Control on 2900XL

[daniel.bowen]

I have configured port storm control on a 2900XL as below:

port storm-control unicast threshold rising 1000 falling 500

port storm-control unicast action shutdown

When the pps of that interface reaches 1000, the port shuts down, but when it drops below 500 it does not reopen.

Is there another command I am missing to tell it to reopen when it drops back to 500 pps?

Thanks in advance,

Daniel,

[steve.barlow]

The switch is doing as you told it. Once the threshold of unicast is reached, it is shutting down. You must manually no shut the port as it is placed in an error-disabled state. You can set it to send you a trap, so that you know you have to unshut the port.

But do you want to shut the port or just block the traffic once the threshold is exceeded. If you want to shut the port, leave the config as is (maybe add send trap as well so you know when this happens) and manually unshut the port (bothersome, thats why you may want to only shut the port for broadcast and multicast traffic). If you want to only block the exceeded traffic so that it can forward traffic once again once it fails below your thresold, remove the action shutdown command.

Key is that there is a difference between blocking traffic and shutting down a port, you can block without shutting down.

Hope it helps.

Steve

[daniel.bowen]

Thanks for your response !

So if I just enter the command:

port storm-control unicast threshold rising 1000 falling 500

When the pps rises to 1000, all traffic will be blocked until it falls to 500?

Is this correct?

Daniel,

[steve.barlow]

That is what should happen. Let me know.

Steve

[daniel.bowen]

Thanks very much Steve,

Daniel,

[leowchongwei]

Hi,

Sorry to "borrow" this thread, i hope someone can explain to me what's port storm? Thanks

[steve.barlow]

As per cisco: "A packet storm occurs when a large number of broadcast, unicast, or multicast packets are received on a port. Forwarding these packets can cause the network to slow down or to time out. Storm control is configured for the switch as a whole but operates on a per-port basis. By default, storm control is disabled.

Storm control uses high and low thresholds to block and then restore the forwarding of broadcast, unicast, or multicast packets. You can also set the switch to shut down the port when the rising threshold is reached."

See link for full details: http://www.cisco.com/univercd/cc/td/doc/product/lan/c2900xl/29_35wc3/sc/swgports.htm#xtocid5

Hope it helps.

Steve