Cross-Stack EtherChannel on Cisco 3650, StackWise-160

[eb_3402]

Hi all,

We are required to use ethernet links between Device-1 and Cisco 3650 switches in trunk mode.(You may see given figure below.) We are able to run trunk in device-1 without using any network protocol-based software so we have decided on using cross-stack EtherChannel on Cisco switches also ON mode without running LACP. According to given topology do we have to use Stack-Wise 160 cable between Cisco switches. We are concerned about it because such cable does not allow long-distance usage.  

Thanks in advance for your invaluable advices.

[doodles6970]

Hello,

Can you confirm what
Model of switch Device 1 is?

This is quite a common scenario that I see quite a lot. Usually I would do the following but only if you have the Infrastructure.

I would use the SFP ports on the switch. I would patch in both interfaces then then run the fibre back to the 3650. I would balance them out so you have one pair going to 3650-1 - Device1 SFP port 1
And then do the opposite for port 2
3650-2 - Device1 SFP port 2.

I would then create the LACP port channel back to the 3650 and then you have a 2GB link. And proving both fault tolerance should you have a fibre break / switch failure in the stack.
If at all possible I would do this at 10GB providing Device 1 is SFP+ capable and you have SFP+ ports on the 3650.

This is the only option that you can feasibly do in my eye if you are out of stackwise distance.

I hope this helps answer your question.

Ryan

[eb_3402]

Hi,

First of all thanks your suggestion,

Actually the device 1 and device 2 are embedded systems  and we are using a small embedded system Ethernet switch capable of supporting Ethernet trunk mode. By the way all of lines are configured to allow 100 Mbps full-dublex traffic rate. If we can eliminate distance problem, as far as I see the only way to deploy cross-stack Etherchannel among 3650's is to use StackWise-160 cable between them. Could you please verify whether or not I'm right?

Thanks

[doodles6970 · Accepted solution]

Yes this would be correct, you would stack to two 3650’s together to one logical switch.
It may be worth noting for the future that the 3850 support a virtual stacking feature which would help with the distance of the stack cables!

Useful article here

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/16-3/configuration_guide/b_163_consolidated_3850_cg/b_163_consolidated_3850_cg_chapter_010101001.pdf

[Leo Laohoo]

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@eb_3402 wrote:

According to given topology do we have to use Stack-Wise 160 cable between Cisco switches. 

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If you want to do etherchannel across two or more physical switches, Stacking is mandatory otherwise you'll see MAC address flapping across switches.

[eb_3402]

Hi all,

I have another question about the given topology, we have decided on using CrossStack EtherChannel by using ON mode in Cisco 3650 switches. We are using ON mode because we have to fullfill network redundancy without using a protocol (LACP, PAgP etc.) Actually this topology has some additional core switches, which are not shown in the figure, so RSTP will be used among all Cisco switches to update topology information. As can be seen clearly,  "Device 1" and "Device 2" are so-called edge devices and we do not want to run RSTP on them. As a conclusion, my question is that do we need to define ports, symbolized as blue dotted  yellow circles,  located on Cisco switches as EDGE ports for RSTP or StackWise Etherchannel already accepts them as EDGE ports?

Thanks