3550 switch ports broadcasting issue

[imtiazmuhammad]

Hi

I am getting alerts related to broadcast threshold limit. Alert indicates that the input packet broadcast percentage exceeds BroadcastThreshold. but i didnt set any threshold. Is there any way to block the broadcast traffic on 3550 ports. Mostly broadcast is occuring on ports within one or two VLANs. NICs on servers are fine and configured full dup with 100Mbps.

any thoughts, please help if possible.

Thanks

Muhammad Imtiaz

[aashish.c]

Hi,

Please paste the type of error/warning messages coming in your switch. Have you configured storm control on ports ?

Check the driver of NIC cards and upgrade it to the latest, a faulty NIC may generate un necessary broadcast. Try connecting another PC on that port and cehck the behavior.

you can set the limit of broadbast traffic on ports using "storm-control" command and set the threshold as per your requirement. but be cautious about setting the threshold , wrong settings may result into blocking of port. here is the usage of command :

http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12225se/3550scg/swtrafc.htm

kindly update

regards

aashish C

[imtiazmuhammad]

Aashish

Here is the error message.

Event Message: Port_Performance_dot3_Ethernet PORT-h09024csw9001.mas.att.com/1.37 [Fa0/37] [h09024exb4002 Z4-MGMT] [ATT] is HighBroadcastRate. Indicates that the input packet broadcast percentage exceeds BroadcastThreshold.

I have configured the storm control on all ports. NIC cannot be faulty since this just occur at a particular time in nights. I also configured the flow control receive/send command but didnt work.

Any other idea, this prob could cost me my job so please help.

I'll work with ehtereal, lets see.

thanks

imtiaz

[amit-singh]

Hi,

You can also set up a local SPAN(source port analyzer) session to see which PC is generating the broadcast. You can use a free tool like ethereal and sniff the traffic.It will list the mac-address which is behaving unexpectedly.

Here is the link :

http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12120ea2/3550scg/swspan.htm

HTH,

-amit singh

[imtiazmuhammad]

Cant set SPAN, have no port available on switch and cant move servers. It doesnt harm the production work but keep generating the alarms.

Thanks for ur help

Imtiaz