Unanswered Question
May 21st, 2008

We are replacing our core Avaya switch with a 6513. Our edge switches are mostly 3750s. I have a working config that is testing out so far.

I need to test building EtherChannels. A few buildings on campus have 2 GIG uplinks. If a building has a single existing uplink and you wish to add an etherchannel. What is the process in steps so as to not disrupt existing traffic? Can you make the config changes at the 3750 and 6513 and then just plug in the fiber at boths ends without interuption? Or is it best to do this off hours. Does the existing link drop so that you better plan to visit the console of the 3750 during the process.


I have this problem too.
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glen.grant Wed, 05/21/2008 - 10:18

Do it off hours or a change window , just make the connecting links as follows.

channel-group x mode desirable non-silent

cef2lion2 Thu, 05/22/2008 - 11:49

For Layer 2 etherchannels. The documentations says.

For Cisco IOS to create port channel interfaces for Layer 2 EtherChannels, the Layer 2 LAN ports must be connected and functioning.

If this is so. You can not create the etherchannels ahead of connecting the ports? Wouldn't having both ports active prior to making them an etherchannel create a network loop.


glen.grant Thu, 05/22/2008 - 17:24

It would not create a loop if spanning tree is running , that would put one side into blocking mode if the channel is not created.

Anonymous (not verified) Fri, 05/23/2008 - 04:49

You are going to want to configure etherchannel while the links you want in the channel are in a shut down state. If you bring up your channel group on one side while the other is not configure they may go into "suspended" state.

Plus while the channel is going up it can take up the 15 seconds for traffic to be permitted over the links

Best to do it off hours or in a window...


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