Solved: Cross stacked Etherchannel between 3750 stacks

rcboersma · ‎08-09-2007

In our network design we want to create an ethernetchannel between two 3750E stacks, using two ports from switch 1 and two ports for switch 2 in Stack A and two ports from switch 1 and two ports for switch 2 in Stack B. This way we create a "fully meshed" etherchannel between the two stacks. Has anyone done this or knows that this works?

Switch 1 stack A ---Switch 1 stack B

..............................X.................

Switch 2 stack A ---Switch 2 stack B

wochanda · ‎08-09-2007

Since each stack is treated as 1 logical switch, there is nothing wrong with setting it up like this.

I've seen it work fine.

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Pavel Bykov · ‎08-09-2007

I know that cross-stack etherchannel works very well. But beware, that spanning tree will block one way, since you cannot have loop in Spanning Tree.

Best solution would be to connect the two stacks into one. Are your switches too far apart?

Also, don't forget how stackwise technology works - Every packet is sent to stack ring, and so on...

http://www.cisco.com/en/US/customer/products/hw/switches/ps5023/products_white_paper09186a00801b096a.shtml

rcboersma · ‎08-09-2007

Ceska,

Yes our switches are to far apart to put them in one stack.

There wouldn't be a loop with STP blocking one way. From a logical design point this would be just one switch connected to another switch with one etherchannel between them. Where the etherchannel consists of four physical ports.

-------------------..............-----------------

|Switchstack A |----4----|Switchstack B |

-------------------..............-----------------

wochanda · ‎08-09-2007

Since each stack is treated as 1 logical switch, there is nothing wrong with setting it up like this.

I've seen it work fine.

rcboersma · ‎08-09-2007

William,

Pleased to hear that you have seen this work just fine.

Thanks a lot

leon.mflai · ‎08-10-2007

Hi all,

I noticed and exprienced some issues when enabling cross-stacking Etherchannel across 2 x 3750. May I know if you guys have same exprience as well?