40Gb Port-Channel between 3750-x switch stacks

[voipis4me]

I have a customer that would like a 40Gb port-channel between two 3750-x switch stacks.  When I try to activate four 10Gb ports in the channel, they go into error-disable.  However, I am able to create a 20Gb port-channel without issue.  I have had my configurations verified to Cisco best practice.

Is there a limitation on the amount of throughput that the 3750-x can handle?  According to the data sheet the 3750X-48T can handle 101.2mpps, based on two 10Gb uplinks so if my math is correct then a stack of two 3750X-48T should be able to handle 202.4mpps.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/data_sheet_c78-584733.html

Thank you in advance for your help.

[Joseph W. Doherty]

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Posting

Hmm, I wonder whether the stack ring's bandwidth might cause an issue.  Will a port-channel of 3 x 10 gig come up?

[voipis4me]

We did not attempt a 3 x 10Gb channel. 

[Leo Laohoo]

they go into error-disable.

Can you please post the output to the following commands:

1.  sh int status err;

2.  sh log