1. Is NEM upgrade is mandatory during firmware upgrade of chassis? This firmware upgrade is being done because one the newly inserted blade is not getting detected. I hope only CMM upgrade is required for recognizing new blades. Am i right?
I have only ever used the passive NEMs so I am not quite sure about the first part of the question and sometimes you do need an update of the CMM to properly detect and use a new blade's SP.
2. Whether the downtime for all blades is required if I am doing only CMM firmware upgrade?
The CMM update itself does not require blades to be shutdown. But there is a minimum fw requirement for the blade SPs that you need to check. You may have to update some blade SPs before you can safely update the CMM and the SPs require shutdowns.