Broadcom card having Multiple MAC addresses?

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Aug 4th, 2010
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I have a Cisco switch configured to only allow one MAC address per port. I recently added several new identical Dell systems to the switch, each with an internal Broadcom NIC.

When the Dells are doing large file transfers over the network, their switch ports keep getting "err-disabled" due to showing multiple MAC addresses: the actual MAC and then random junk addresses usually beginning with several zeroes. Any idea why this is happening?



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Nagaraja Thanthry Wed, 08/04/2010 - 10:28
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Can you give some information about the switches (Model number, code version

etc) you are using? Sometime ago, there was a bug filed for bogus MAC

addresses showing up on the switch. You could be hitting that.



shullmf35806 Wed, 08/04/2010 - 10:46
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I believe it is a Catalyst 3560? I will have to double-check with the network admin. I will get back to you.


Collin Clark Wed, 08/04/2010 - 11:50
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We have this sporadically happening across our network too, but have not been able to track it down yet. Hopefully it's a bug.

shullmf35806 Wed, 08/04/2010 - 13:40
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The switch is a Catalyst 3550, with IOS version C3550-ipservicesk9-122-40.SE.bin.

Thanks for the help.

Nagaraja Thanthry Thu, 08/05/2010 - 18:29
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Seems like the bug was related to some CRC issues and 3550 switch reading wrong MAC address on the wire. Can you check the interfaces to see if there are any CRC errors on the interface? Also, if you have not done so already, can you verify and if needed update the drivers on the broadcom NICs? Also, please don't forget to set the speed/duplex to auto on both switch and the PC side.

Hope this helps.



shullmf35806 Fri, 08/06/2010 - 11:26
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I checked the switch and there were no CRC errors, nor any other errors.

The Broadcom NICs have updated drivers. (I even tried rolling back to a few previous ones)

Duplex is set to auto on both the problematic systems and the switch.

Any other ideas? Thanks for your help.


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