Solved: Cross-Stack 10-Gigabit EtherChannel on 3750E/3750-X/2960-S - Page 2

shillings · ‎01-29-2012

According to the following Cisco webpage, cross-stack 10-Gigabit EtherChannel is possible on the 3750 with up to two 10-Gigabit modules, using LACP: http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_example09186a00806cb982.shtmlhttp://

However, the webpage doesn't confirm if this functionality is restricted to a particular 3750 model, such as 3750E, or if it applies to all models. It also doesn't specify any particular IOS feature set. I've tried Cisco Software Advisor but it doesn't list this feature on either the 3750E or 3750-X. Can anyone help?

Next question, does anyone know if this is possible on the 2960-S switches (i.e. cross-stack 10gig EtherChannel)?

Leo Laohoo · ‎01-31-2012

Errr ... That depends on your network.

In my humble opinion, running two 10Gbps links as an etherchannel is OK if you consider each link as a redundant link to the other. IF, however, one is to get the impression that you can push 20Gbps of traffic down the etherchannel, then this I don't agree.

If you want to do multiple stacking etherchannel and at 10Gbps each, then you really can't beat a 3750E/3750X.

shillings · ‎01-31-2012

leolaohoo wrote:

Errr ... That depends on your network.

In my humble opinion, running two 10Gbps links as an etherchannel is OK if you consider each link as a redundant link to the other. IF, however, one is to get the impression that you can push 20Gbps of traffic down the etherchannel, then this I don't agree.

If you want to do multiple stacking etherchannel and at 10Gbps each, then you really can't beat a 3750E/3750X.

OK, so it's fine in theory, but not in practice.

We won't have an opportunity to lab test this, so will play safe and recommend all 3750s.

Thanks for sharing.

Leo Laohoo · ‎02-01-2012

We won't have an opportunity to lab test this, so will play safe and recommend all 3750s.

You mean 3750X?

End-of-Sale and End-of-Life Announcement for the Cisco Catalyst 3750G, 3560G, 3750-E, and 3560-E Series Switches

shillings · ‎02-01-2012

I hadn't seen that. Thank you.

I see the replacement for the 3750-E is the -X, but the X has half the StackWise throughput. Hope Cisco plan to address that soon. Have you heard anything?

Leo Laohoo · ‎02-01-2012

I see the replacement for the 3750-E is the -X, but the X has half the StackWise throughput. Hope Cisco plan to address that soon. Have you heard anything?

That's gotta be a type-o. The StackWise backplane for the 3750X and the 3750E would be the same at 32Gbs full duplex. It won't go any higher than that, I believe, because some Business Unit (BU) won't like "competition" if it goes beyond 40 or 48 Gbps.

shillings · ‎02-01-2012

I suspect I remembered incorrectly. Data sheet says 64Gbps. Thanks for the correction.

Leo Laohoo · ‎02-01-2012

I suspect I remembered incorrectly. Data sheet says 64Gbps. Thanks for the correction.

Don't worry. You're not alone. I get confused whether the numbers are in half or full duplex.

shillings · ‎02-29-2012

Cisco confirmed to me this should work with a pair of 2960-S switches (i.e. 20Gbps cross-stack load balanced with a 3750-X stack).

They highlighted the point that it only applies to known unicast traffic, not multicasts, broadcasts or unknown unicasts. They did suggest that more than two 2960-S's in the stack might require some tweaking of the EtherChannel load balancing algorithm to best utilise the two 10Gbps uplinks.

They were also able to confirm that FlexStack operates the same way as StackWise Plus (not StackWise) in that it can switch unicast traffic locally without having to traverse the stack.

I know its a very simple setup, but still nice to visualise, so added a diagram.

Leo Laohoo · ‎02-29-2012

I'll be interesting to see with the result of the 2960S running load balanced on two 10Gbps link. Please keep us posted.