Stackwise Virtual on C9407 with SUP-2?

[SIMMN]

I have a pair of C9407, each is installed with a pair of SUP-2 (active/standby). I want to setup the two 9407 as a stackwise virtual domain. 

Referencing to the High-Availability guide, linked below, quote "Cisco StackWise Virtual can be configured only on one supervisor module per chassis. You must not install two supervisor modules in each chassis used in the Cisco StackWise Virtual solution."

Obviously, with this restriction, I can not setup my two 9407 as a stackwise virtual domain without removing one Sup-2 from each chassis...But I also want to understand why this restriction? 

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9400/software/release/17-9/configuration_guide/ha/b_179_ha_9400_cg/configuring_cisco_stackwise_virtual.html#restrictions_for_cisco_stackwise_virtual_9400

[SIMMN]

Still waiting...anyone??

[Reza Sharifi]

If you are planning on using StackWise virtual, you don't need a second sup in each switch because once you configure StackWise virtual both physical switches logically become one unit, and you use one IP to manage the the whole stack.

HTH

[SIMMN]

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@Reza Sharifi wrote:

If you are planning on using StackWise virtual, you don't need a second sup in each switch 

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Totally agree! I would not need the dual SUP...But why I am not allowed to within the software if I so chose to do stackwise virtual with dual SUP in each chassis?

[Reza Sharifi · Accepted solution]

I can't be 100% sure, but I think that is because Cisco did not have much success with the way failover worked using dual sups in each chassis in the early days of StackWise Virtual which was called VSS. The main issue with dual sup is VSS or StackWise Virtual is that if for example, you lose the primary sup in switch-1, the chassis will failover to switch-2 even if you have a second sup in switch-1. 

HTH

[SIMMN]

Thanks for the info.