I search at all cisco pages about support of VSS quad supervisor 2T support.
Even relase notes, q&a etc.
But until now I don’t found any pros or contra.
Customer use the newest IOS 15.1.1-SY
Customer uses already several system with quad sup720, has also experience.
Customers actual state is:
With quad sup 2T the 2nd sup2t of each VSS-chassis drops in rommon.
Without VSS the same sup2t comes up either as active or standby!
we are stuck in the same problem that you are facing, we have noticed that in the 15.x ios the VSS is not supported using dual sup's per chassis.
now i am trying to downgrade to version 12.2(50)sy3 as it should support the dual sim per chassis (quad sups for both chassis).
i hope this will help both of us
sup 2T does not support quad supervisor VSS
>> VSS mode does not support supervisor engine redundancy within a chassis.
It shouldn't be a question of IOS version, but also the sup720 config guide for the same IOS version reports the same limitation
As reported here in the forums, support for quad supervisor in VSS sup 2T may be added in the future. but it shouldn't be available now.
Hope to help