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help cisco 3550 flooding or loop occure issue.

Dear  Experts,

I have attach of my cisco 3550 running-config.

We are using cisco 3550 48P for our users. there are two authentication server to authenticat our all users from both the server.

Both server connected port 1 and port 2. and other from port 3 to 48 connected IP DSLAM (48 port).

approx more than 50 users connetd per interface from port 3 to 48.

we are facing the problem of flooding or loop occure from any one or two ports for the last couple of days .

the problem is when flooding or loop occure that time any 4 or 5 ports are shutdown after i less the security any one port to remove Storm-control broadcast level 5.00 then it working fine . how many broadcast lavel to set when more than 50 users connet per port ??

can i set port 1 and port 2 as a trunk port when it is conneted billing authentication server not with router. ??

So what is the problem and how to slove it , when flooding or loop occure from any one port to effect only this port should be shut and no effect to any other ports,

Thanks in ADV,


New Member

Re: help cisco 3550 flooding or loop occure issue.

Dear Ganesh & Experts,

Pl help me regarding my above mention issue cause it's very URGENT for me.

Thanks in ADV,


Re: help cisco 3550 flooding or loop occure issue.

Hi Vaibhav,

The main important thing while configuraing a strom control is the thrshold value with the strom control.The thresholds are in reference to the total available bandwidth on an interface. So if you set your storm control for broadcasts to 10%, and you have a 10-Mbps Ethernet line connected, you will allow up to 1 Mbps of broadcasts every second before suppressing anything. With a 100 Mbps line, 10 Mbps of broadcasts would be allowed before suppressing.

Each 1-second interval is different from the next. So there may be some disconnect between what the switch is perceiving in a measurement and what you are looking at.

Anything above the assigned threshold is dropped, but only during that particular time measurement. The next 1-second timeslot starts the count at zero again.

Cat3550(config-if)# storm-control broadcast level 10

And i dont think you need to configure trunk on port 1 and port 2.




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