Catalyst 9600 - StackWise Virtual in dual-supervisor mode: Active supervisor goed down

[Danilo Silenzi]

Hi,

I have a doubt about the behavior of the VirtualSTacck Wise. If the active SUP goes down the stand-by SUP takes control thanks to the SSO. Are the line cards of the chassis with the supervisor down, managed by the supervisor of the other chassis, or do they remain down until their supervisor returns up?

Because in the Quad-supervisor mode, if the Active SUP goes down, the local redendancy provides this behavior:

 "The in-Chassis standby supervisor in failed chassis will fully boot up and re-initialize all the local line cards automatically without any human intervention leading to become the StackWise Virtual Standby Switch and this whole process is completed within few minutes."

Thanks.

Regards, Danilo.

[brselzer · Accepted solution]

Hello,

In a dual-sup setup, if one sup goes down that chassis will go down. This is why it is best practice to have a port-channel going to both members of stackwise virtual. If one member goes down, all downstream switches will lose one leg of their port-channel and continue to send through the other member. 

As you mentioned, you can run quad sup if you choose to improve your redundancy because then the chassis that went down will recover on its own using the secondary sup. However, that chassis will still be down for a couple minutes so you still want to have redundant connections to both members.

Hope that helps!