etherchannel question

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Jul 21st, 2010
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Recently I've migrated a filer from 6509 to 4900M. I copied the same setup from 6509 to 4900M, but It caused problem. On the filer, a virtual interface is trunk between 4 physical interface sharing the same mac address and IP. The setup on 6509 was to have 2 L2 port channels and each port channel has 2 physical interfaces. It worked well. However, when it migrated to 4900M, the switch has very high CPU utilization. lt looks fine on the filer side though. In order to fix it, I created a port channel that contains 4 physical interfaces at 4900M and it backs to normal. I wonder how come it wasn't a problem at 6509, but at 4900M. Any idea?

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Jon Marshall Wed, 07/21/2010 - 09:58
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cheng.sid wrote:


Recently I've migrated a filer from 6509 to 4900M. I copied the same setup from 6509 to 4900M, but It caused problem. On the filer, a virtual interface is trunk between 4 physical interface sharing the same mac address and IP. The setup on 6509 was to have 2 L2 port channels and each port channel has 2 physical interfaces. It worked well. However, when it migrated to 4900M, the switch has very high CPU utilization. lt looks fine on the filer side though. In order to fix it, I created a port channel that contains 4 physical interfaces at 4900M and it backs to normal. I wonder how come it wasn't a problem at 6509, but at 4900M. Any idea?


Sidney


If the filer is combining all 4 ports into one virtual interface why did you use 2 etherchannels on the 6500 and how did you do this ? I would have thought from your description that the 4900 was the correct setup. I'm not sure how the 6500 managed to work with that configuration.


Perhaps an STP issue with the 4900 ?


Jon

manish arora Wed, 07/21/2010 - 17:39
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Interesting !  how were you connected physically from the filer server to the 6509 ? were you using two different cards on 6509 for connecting two port channels ?

manish

Sidney Cheng Wed, 07/21/2010 - 19:02
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yes. manisharora111. 2 port channels are on 2 different cards. Does it make a different if they are on the same card?

manish arora Thu, 07/22/2010 - 08:47
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I am not sure completely but with different cards on 6509 they do not sync their cam table by default so when you had two channels on multiple cards you did not see any problems , where as if you connect then single card there is going to be a conflict of same mac from two different port channels.

hope it helps

Manish

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