Hi,
1. So, is it still the case that StackWise Virtual is ONLY a chassis-based technology (though I know that the 3850 used to support it, which is weird because its a fixed configuration switch)?
That is correct. It is a chassis-based technology, and only 2 chassis can be part of a StackWise Virtual domain.
2. Is it true that StackWise virtual DOES NOT support DUAL SUPs in EACH chassis? I need this 100% verified with no doubts before I go to my client. I did research it greatly on Cisco.com, BUT I read a couple of docs that seem to contradict each other.
Cisco has been going back and forth with these for many years now. They started the same thing with the 6500 and 6700 series VSS with dual sup, but it really never worked the way it should because when one sup goes down in a chassis, the whole chassis goes out. So, what is really the purpose of having 2 sups per chassis? So. I am not 100% sure if they finally gave up on 2 sups per chassis or not, but I would never use 2 sups per chassis anyways, as I think it is a waste of money. Both VSS and StackWise Virtual work fine with one sup in each chassis.
4. And MUST you have DUAL SUPs in EACH of the chassis to do ISSU, or can a switch chassis have a SINGLE SUP and still support ISSU—meaning, the SUP is having its code upgraded while the chassis continues to forward all traffic (maybe the answer is yes because of CEF)?
No, you don't have to have 2 sups per chassis to do ISSU. ISSU can be used with one sup in each chassis.
The basic concept is to reload one chassis at a time with no downtime, but ISSU does not always work flowlessly and has its own limitations.
HTH
